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freebsd-dev/sys/kern/kern_lock.c

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/* -> /*- for copyright notices, minor format tweaks as necessary
2005-01-06 23:35:40 +00:00
/*-
sys/kern: adoption of SPDX licensing ID tags. Mainly focus on files that use BSD 2-Clause license, however the tool I was using misidentified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts.
2017-11-27 15:20:12 +00:00
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* Copyright (c) 2008 Attilio Rao <attilio@FreeBSD.org>
* All rights reserved.
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* notice(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
* 2. Redistributions in binary form must reproduce the above copyright
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* notice(s), this list of conditions and the following disclaimer in the
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
* documentation and/or other materials provided with the distribution.
*
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
*/
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#include "opt_ddb.h"
Add software PMC support. New kernel events can be added at various location for sampling or counting. This will for example allow easy system profiling whatever the processor is with known tools like pmcstat(8). Simultaneous usage of software PMC and hardware PMC is possible, for example looking at the lock acquire failure, page fault while sampling on instructions. Sponsored by: NETASQ MFC after: 1 month
2012-03-28 20:58:30 +00:00
#include "opt_hwpmc_hooks.h"
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
Use __FBSDID().
2003-06-11 00:56:59 +00:00
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
#include <sys/param.h>
Fixup r240424: On entering KDB backends, the hijacked thread to run interrupt context can still be idlethread. At that point, without the panic condition, it can still happen that idlethread then will try to acquire some locks to carry on some operations. Skip the idlethread check on block/sleep lock operations when KDB is active. Reported by: jh Tested by: jh MFC after: 1 week
2012-12-22 09:37:34 +00:00
#include <sys/kdb.h>
Add missing includes of sys/ktr.h.
2001-10-11 17:53:43 +00:00
#include <sys/ktr.h>
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
#include <sys/lock.h>
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#include <sys/lock_profile.h>
Include <sys/lockmgr.h> for the definitions of the locking interfaces that are implemented here instead of depending on namespace pollution in <sys/lock.h>. Fixed nearby include messes (1 disordered include and 1 unused include).
2002-08-27 09:59:47 +00:00
#include <sys/lockmgr.h>
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#include <sys/lockstat.h>
- machine/mutex.h -> sys/mutex.h - The initial lock_mtx mutex used in the lockmgr code is initialized very early, so use MUTEX_DECLARE() and MTX_COLD.
2000-10-20 07:28:00 +00:00
#include <sys/mutex.h>
Include <sys/lockmgr.h> for the definitions of the locking interfaces that are implemented here instead of depending on namespace pollution in <sys/lock.h>. Fixed nearby include messes (1 disordered include and 1 unused include).
2002-08-27 09:59:47 +00:00
#include <sys/proc.h>
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#include <sys/sleepqueue.h>
- Replace the series of DEBUG_LOCKS hacks which tried to save the vn_lock caller by saving the stack of the last locker/unlocker in lockmgr. We also put the stack in KTR at the moment. Contributed by: Antoine Brodin <antoine.brodin@laposte.net>
2005-08-03 04:48:22 +00:00
#ifdef DEBUG_LOCKS
#include <sys/stack.h>
#endif
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
#include <sys/sysctl.h>
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#include <sys/systm.h>
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#include <machine/cpu.h>
Add WITNESS support to lockmgr locking primitive. This support tries to be as parallel as possible with other locking primitives, but there are differences; more specifically: - The base witness support is alredy equipped for allowing lock duplication acquisition as lockmgr rely on this. - In the case of lockmgr_disown() the lock result unlocked by witness even if it is still held by the "kernel context" - In the case of upgrading we can have 3 different situations: * Total unlocking of the shared lock and nothing else * Real witness upgrade if the owner is the first upgrader * Shared unlocking and exclusive locking if the owner is not the first upgrade but it is still allowed to upgrade - LK_DRAIN is basically handled like an exclusive acquisition Additively new options LK_NODUP and LK_NOWITNESS can now be used with lockinit(): LK_NOWITNESS disables WITNESS for the specified lock while LK_NODUP enable duplicated locks tracking. This will require manpages update and a __FreeBSD_version bumping (addressed by further commits). This patch also fixes a problem occurring if a lockmgr is held in exclusive mode and the same owner try to acquire it in shared mode: currently there is a spourious shared locking acquisition while what we really want is a lock downgrade. Probabilly, this situation can be better served with a EDEADLK failing errno return. Side note: first testing on this patch alredy reveleated several LORs reported, so please expect LORs cascades until resolved. NTFS also is reported broken by WITNESS introduction. BTW, NTFS is exposing a lock leak which needs to be fixed, and this patch can help it out if rightly tweaked. Tested by: kris, yar, Scot Hetzel <swhetzel at gmail dot com>
2008-02-06 00:37:14 +00:00
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
#ifdef DDB
#include <ddb/ddb.h>
#endif
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
Add software PMC support. New kernel events can be added at various location for sampling or counting. This will for example allow easy system profiling whatever the processor is with known tools like pmcstat(8). Simultaneous usage of software PMC and hardware PMC is possible, for example looking at the lock acquire failure, page fault while sampling on instructions. Sponsored by: NETASQ MFC after: 1 month
2012-03-28 20:58:30 +00:00
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
PMC_SOFT_DECLARE( , , lock, failed);
#endif
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS)));
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#define SQ_EXCLUSIVE_QUEUE 0
#define SQ_SHARED_QUEUE 1
#ifndef INVARIANTS
#define _lockmgr_assert(lk, what, file, line)
#endif
Don't modify curthread->td_locks unless INVARIANTS is enabled. This field is only used in a KASSERT that verifies that no locks are held when returning to user mode. Moreover, the td_locks accounting is only correct when LOCK_DEBUG > 0, which is implied by INVARIANTS. Reviewed by: jhb MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D3205
2015-08-02 00:03:08 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#define TD_SLOCKS_INC(td) ((td)->td_lk_slocks++)
#define TD_SLOCKS_DEC(td) ((td)->td_lk_slocks--)
#ifndef DEBUG_LOCKS
#define STACK_PRINT(lk)
#define STACK_SAVE(lk)
#define STACK_ZERO(lk)
#else
#define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack)
#define STACK_SAVE(lk) stack_save(&(lk)->lk_stack)
#define STACK_ZERO(lk) stack_zero(&(lk)->lk_stack)
#endif
#define LOCK_LOG2(lk, string, arg1, arg2) \
if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \
CTR2(KTR_LOCK, (string), (arg1), (arg2))
#define LOCK_LOG3(lk, string, arg1, arg2, arg3) \
if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \
CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3))
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
#define GIANT_DECLARE \
int _i = 0; \
WITNESS_SAVE_DECL(Giant)
#define GIANT_RESTORE() do { \
Annotate Giant drop/pickup macros with __predict_false They are used in important places of the kernel with the lock not being held majority of the time. Sponsored by: The FreeBSD Foundation
2018-12-07 12:06:03 +00:00
if (__predict_false(_i > 0)) { \
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
while (_i--) \
mtx_lock(&Giant); \
WITNESS_RESTORE(&Giant.lock_object, Giant); \
} \
} while (0)
#define GIANT_SAVE() do { \
Annotate Giant drop/pickup macros with __predict_false They are used in important places of the kernel with the lock not being held majority of the time. Sponsored by: The FreeBSD Foundation
2018-12-07 12:06:03 +00:00
if (__predict_false(mtx_owned(&Giant))) { \
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
WITNESS_SAVE(&Giant.lock_object, Giant); \
while (mtx_owned(&Giant)) { \
_i++; \
mtx_unlock(&Giant); \
} \
} \
} while (0)
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
static bool __always_inline
LK_CAN_SHARE(uintptr_t x, int flags, bool fp)
{
if ((x & (LK_SHARE | LK_EXCLUSIVE_WAITERS | LK_EXCLUSIVE_SPINNERS)) ==
LK_SHARE)
return (true);
if (fp || (!(x & LK_SHARE)))
return (false);
if ((curthread->td_lk_slocks != 0 && !(flags & LK_NODDLKTREAT)) ||
(curthread->td_pflags & TDP_DEADLKTREAT))
return (true);
return (false);
}
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
#define LK_TRYOP(x) \
((x) & LK_NOWAIT)
#define LK_CAN_WITNESS(x) \
(((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x))
#define LK_TRYWIT(x) \
(LK_TRYOP(x) ? LOP_TRYLOCK : 0)
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#define lockmgr_disowned(lk) \
(((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC)
lockmgr: avoid atomic on unlock in the slow path The code is pretty much guaranteed not to be able to unlock. This is a minor nit. The code still performs way too many reads. The altered exclusive-locked condition is supposed to be always true as well, to be cleaned up at a later date.
2018-05-18 22:57:52 +00:00
#define lockmgr_xlocked_v(v) \
(((v) & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread)
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
#define lockmgr_xlocked(lk) lockmgr_xlocked_v(lockmgr_read_value(lk))
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
static void assert_lockmgr(const struct lock_object *lock, int how);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#ifdef DDB
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
static void db_show_lockmgr(const struct lock_object *lock);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#endif
Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. With current lock classes KPI it was really difficult because there was no way to pass an rmtracker object to the lock/unlock routines. In order to accomplish the task, modify the aforementioned functions so that they can return (or pass as argument) an uinptr_t, which is in the rm case used to hold a pointer to struct rm_priotracker for current thread. As an added bonus, this fixes rm_sleep() in the rm shared case, which right now can communicate priotracker structure between lc_unlock()/lc_lock(). Suggested by: jhb Reviewed by: jhb Approved by: re (delphij)
2013-09-20 23:06:21 +00:00
static void lock_lockmgr(struct lock_object *lock, uintptr_t how);
Add the OpenSolaris dtrace lockstat provider. The lockstat provider adds probes for mutexes, reader/writer and shared/exclusive locks to gather contention statistics and other locking information for dtrace scripts, the lockstat(1M) command and other potential consumers. Reviewed by: attilio jhb jb Approved by: gnn (mentor)
2009-05-26 20:28:22 +00:00
#ifdef KDTRACE_HOOKS
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
static int owner_lockmgr(const struct lock_object *lock,
struct thread **owner);
Add the OpenSolaris dtrace lockstat provider. The lockstat provider adds probes for mutexes, reader/writer and shared/exclusive locks to gather contention statistics and other locking information for dtrace scripts, the lockstat(1M) command and other potential consumers. Reviewed by: attilio jhb jb Approved by: gnn (mentor)
2009-05-26 20:28:22 +00:00
#endif
Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. With current lock classes KPI it was really difficult because there was no way to pass an rmtracker object to the lock/unlock routines. In order to accomplish the task, modify the aforementioned functions so that they can return (or pass as argument) an uinptr_t, which is in the rm case used to hold a pointer to struct rm_priotracker for current thread. As an added bonus, this fixes rm_sleep() in the rm shared case, which right now can communicate priotracker structure between lc_unlock()/lc_lock(). Suggested by: jhb Reviewed by: jhb Approved by: re (delphij)
2013-09-20 23:06:21 +00:00
static uintptr_t unlock_lockmgr(struct lock_object *lock);
track lock class name in a way that doesn't break WITNESS
2006-11-13 05:41:46 +00:00
struct lock_class lock_class_lockmgr = {
Use C99-style struct member initialization for lock classes.
2007-03-09 16:19:34 +00:00
.lc_name = "lockmgr",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
.lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE,
Expand lock class with the "virtual" function lc_assert which will offer an unified way for all the lock primitives to express lock assertions. Currenty, lockmgrs and rmlocks don't have assertions, so just panic in that case. This will be a base for more callout improvements. Ok'ed by: jhb, jeff
2007-11-18 14:43:53 +00:00
.lc_assert = assert_lockmgr,
track lock class name in a way that doesn't break WITNESS
2006-11-13 05:41:46 +00:00
#ifdef DDB
Add two new function pointers 'lc_lock' and 'lc_unlock' to lock classes. These functions are intended to be used to drop a lock and then reacquire it when doing an sleep such as msleep(9). Both functions accept a 'struct lock_object *' as their first parameter. The 'lc_unlock' function returns an integer that is then passed as the second paramter to the subsequent 'lc_lock' function. This can be used to communicate state. For example, sx locks and rwlocks use this to indicate if the lock was share/read locked vs exclusive/write locked. Currently, spin mutexes and lockmgr locks do not provide working lc_lock and lc_unlock functions.
2007-03-09 16:27:11 +00:00
.lc_ddb_show = db_show_lockmgr,
track lock class name in a way that doesn't break WITNESS
2006-11-13 05:41:46 +00:00
#endif
Add two new function pointers 'lc_lock' and 'lc_unlock' to lock classes. These functions are intended to be used to drop a lock and then reacquire it when doing an sleep such as msleep(9). Both functions accept a 'struct lock_object *' as their first parameter. The 'lc_unlock' function returns an integer that is then passed as the second paramter to the subsequent 'lc_lock' function. This can be used to communicate state. For example, sx locks and rwlocks use this to indicate if the lock was share/read locked vs exclusive/write locked. Currently, spin mutexes and lockmgr locks do not provide working lc_lock and lc_unlock functions.
2007-03-09 16:27:11 +00:00
.lc_lock = lock_lockmgr,
Add the OpenSolaris dtrace lockstat provider. The lockstat provider adds probes for mutexes, reader/writer and shared/exclusive locks to gather contention statistics and other locking information for dtrace scripts, the lockstat(1M) command and other potential consumers. Reviewed by: attilio jhb jb Approved by: gnn (mentor)
2009-05-26 20:28:22 +00:00
.lc_unlock = unlock_lockmgr,
#ifdef KDTRACE_HOOKS
.lc_owner = owner_lockmgr,
#endif
track lock class name in a way that doesn't break WITNESS
2006-11-13 05:41:46 +00:00
};
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
static __read_mostly bool lk_adaptive = true;
static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL, "lockmgr debugging");
SYSCTL_BOOL(_debug_lockmgr, OID_AUTO, adaptive_spinning, CTLFLAG_RW, &lk_adaptive,
0, "");
#define lockmgr_delay locks_delay
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
struct lockmgr_wait {
const char *iwmesg;
int ipri;
int itimo;
};
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp,
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
int flags, bool fp);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp);
static void
lockmgr_exit(u_int flags, struct lock_object *ilk, int wakeup_swapper)
{
struct lock_class *class;
if (flags & LK_INTERLOCK) {
class = LOCK_CLASS(ilk);
class->lc_unlock(ilk);
}
if (__predict_false(wakeup_swapper))
kick_proc0();
}
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
static void
lockmgr_note_shared_acquire(struct lock *lk, int contested,
uint64_t waittime, const char *file, int line, int flags)
{
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(lockmgr__acquire, lk, contested,
waittime, file, line, LOCKSTAT_READER);
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file, line);
WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file, line);
TD_LOCKS_INC(curthread);
TD_SLOCKS_INC(curthread);
STACK_SAVE(lk);
}
static void
lockmgr_note_shared_release(struct lock *lk, const char *file, int line)
{
WITNESS_UNLOCK(&lk->lock_object, 0, file, line);
LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line);
TD_LOCKS_DEC(curthread);
TD_SLOCKS_DEC(curthread);
}
static void
lockmgr_note_exclusive_acquire(struct lock *lk, int contested,
uint64_t waittime, const char *file, int line, int flags)
{
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(lockmgr__acquire, lk, contested,
waittime, file, line, LOCKSTAT_WRITER);
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, lk->lk_recurse, file, line);
WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | LK_TRYWIT(flags), file,
line);
TD_LOCKS_INC(curthread);
STACK_SAVE(lk);
}
static void
lockmgr_note_exclusive_release(struct lock *lk, const char *file, int line)
{
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
if (LK_HOLDER(lockmgr_read_value(lk)) != LK_KERNPROC) {
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
TD_LOCKS_DEC(curthread);
}
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, lk->lk_recurse, file,
line);
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
static __inline struct thread *
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
lockmgr_xholder(const struct lock *lk)
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
{
uintptr_t x;
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x));
}
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
/*
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* It assumes sleepq_lock held and returns with this one unheld.
* It also assumes the generic interlock is sane and previously checked.
* If LK_INTERLOCK is specified the interlock is not reacquired after the
* sleep.
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
*/
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
static __inline int
sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *wmesg, int pri, int timo, int queue)
{
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
GIANT_DECLARE;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
struct lock_class *class;
int catch, error;
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
The "if" semantic is not needed, just fix this.
2008-05-25 16:11:27 +00:00
catch = pri & PCATCH;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
pri &= PRIMASK;
error = 0;
LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk,
(queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared");
if (flags & LK_INTERLOCK)
class->lc_unlock(ilk);
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0)
lk->lk_exslpfail++;
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
GIANT_SAVE();
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
SLEEPQ_INTERRUPTIBLE : 0), queue);
Revert for r277213: FreeBSD developers need more time to review patches in the surrounding areas like the TCP stack which are using MPSAFE callouts to restore distribution of callouts on multiple CPUs. Bump the __FreeBSD_version instead of reverting it. Suggested by: kmacy, adrian, glebius and kib Differential Revision: https://reviews.freebsd.org/D1438
2015-01-22 11:12:42 +00:00
if ((flags & LK_TIMELOCK) && timo)
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
sleepq_set_timeout(&lk->lock_object, timo);
Revert for r277213: FreeBSD developers need more time to review patches in the surrounding areas like the TCP stack which are using MPSAFE callouts to restore distribution of callouts on multiple CPUs. Bump the __FreeBSD_version instead of reverting it. Suggested by: kmacy, adrian, glebius and kib Differential Revision: https://reviews.freebsd.org/D1438
2015-01-22 11:12:42 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* Decisional switch for real sleeping.
*/
if ((flags & LK_TIMELOCK) && timo && catch)
error = sleepq_timedwait_sig(&lk->lock_object, pri);
else if ((flags & LK_TIMELOCK) && timo)
error = sleepq_timedwait(&lk->lock_object, pri);
else if (catch)
error = sleepq_wait_sig(&lk->lock_object, pri);
else
sleepq_wait(&lk->lock_object, pri);
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
GIANT_RESTORE();
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if ((flags & LK_SLEEPFAIL) && error == 0)
error = ENOLCK;
return (error);
}
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
static __inline int
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
wakeupshlk(struct lock *lk, const char *file, int line)
{
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
uintptr_t v, x, orig_x;
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
u_int realexslp;
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
int queue, wakeup_swapper;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
wakeup_swapper = 0;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
for (;;) {
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
if (lockmgr_sunlock_try(lk, &x))
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
break;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* We should have a sharer with waiters, so enter the hard
* path in order to handle wakeups correctly.
*/
sleepq_lock(&lk->lock_object);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
orig_x = lockmgr_read_value(lk);
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
retry_sleepq:
x = orig_x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
v = LK_UNLOCKED;
/*
* If the lock has exclusive waiters, give them preference in
* order to avoid deadlock with shared runners up.
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
* If interruptible sleeps left the exclusive queue empty
* avoid a starvation for the threads sleeping on the shared
* queue by giving them precedence and cleaning up the
* exclusive waiters bit anyway.
Tweak comments.
2010-01-07 01:19:01 +00:00
* Please note that lk_exslpfail count may be lying about
* the real number of waiters with the LK_SLEEPFAIL flag on
sys/kern: spelling fixes in comments. No functional change.
2016-04-29 22:15:33 +00:00
* because they may be used in conjunction with interruptible
Fix typos.
2010-01-07 01:24:09 +00:00
* sleeps so lk_exslpfail might be considered an 'upper limit'
* bound, including the edge cases.
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
*/
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
realexslp = sleepq_sleepcnt(&lk->lock_object,
SQ_EXCLUSIVE_QUEUE);
if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
if (lk->lk_exslpfail < realexslp) {
lk->lk_exslpfail = 0;
queue = SQ_EXCLUSIVE_QUEUE;
v |= (x & LK_SHARED_WAITERS);
} else {
lk->lk_exslpfail = 0;
LOCK_LOG2(lk,
"%s: %p has only LK_SLEEPFAIL sleepers",
__func__, lk);
LOCK_LOG2(lk,
"%s: %p waking up threads on the exclusive queue",
__func__, lk);
wakeup_swapper =
sleepq_broadcast(&lk->lock_object,
SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
queue = SQ_SHARED_QUEUE;
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
} else {
Exclusive waiters sleeping with LK_SLEEPFAIL on and using interruptible sleeps/timeout may have left spourious lk_exslpfail counts on, so clean it up even when accessing a shared queue acquisition, giving to lk_exslpfail the value of 'upper limit'. In the worst case scenario, infact (mixed interruptible sleep / LK_SLEEPFAIL waiters) what may happen is that both queues are awaken even if that's not necessary, but still no harm. Reported by: Lucius Windschuh <lwindschuh at googlemail dot com> Reviewed by: kib Tested by: pho, Lucius Windschuh <lwindschuh at googlemail dot com>
2010-01-07 00:47:50 +00:00
/*
* Exclusive waiters sleeping with LK_SLEEPFAIL on
* and using interruptible sleeps/timeout may have
* left spourious lk_exslpfail counts on, so clean
* it up anyway.
*/
lk->lk_exslpfail = 0;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
queue = SQ_SHARED_QUEUE;
}
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
if (lockmgr_sunlock_try(lk, &orig_x)) {
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
sleepq_release(&lk->lock_object);
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
break;
}
x |= LK_SHARERS_LOCK(1);
if (!atomic_fcmpset_rel_ptr(&lk->lk_lock, &x, v)) {
orig_x = x;
goto retry_sleepq;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
}
LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
__func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
"exclusive");
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK,
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
0, queue);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
sleepq_release(&lk->lock_object);
break;
}
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk, LOCKSTAT_READER);
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
return (wakeup_swapper);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
}
static void
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
assert_lockmgr(const struct lock_object *lock, int what)
Expand lock class with the "virtual" function lc_assert which will offer an unified way for all the lock primitives to express lock assertions. Currenty, lockmgrs and rmlocks don't have assertions, so just panic in that case. This will be a base for more callout improvements. Ok'ed by: jhb, jeff
2007-11-18 14:43:53 +00:00
{
panic("lockmgr locks do not support assertions");
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
static void
Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. With current lock classes KPI it was really difficult because there was no way to pass an rmtracker object to the lock/unlock routines. In order to accomplish the task, modify the aforementioned functions so that they can return (or pass as argument) an uinptr_t, which is in the rm case used to hold a pointer to struct rm_priotracker for current thread. As an added bonus, this fixes rm_sleep() in the rm shared case, which right now can communicate priotracker structure between lc_unlock()/lc_lock(). Suggested by: jhb Reviewed by: jhb Approved by: re (delphij)
2013-09-20 23:06:21 +00:00
lock_lockmgr(struct lock_object *lock, uintptr_t how)
Add two new function pointers 'lc_lock' and 'lc_unlock' to lock classes. These functions are intended to be used to drop a lock and then reacquire it when doing an sleep such as msleep(9). Both functions accept a 'struct lock_object *' as their first parameter. The 'lc_unlock' function returns an integer that is then passed as the second paramter to the subsequent 'lc_lock' function. This can be used to communicate state. For example, sx locks and rwlocks use this to indicate if the lock was share/read locked vs exclusive/write locked. Currently, spin mutexes and lockmgr locks do not provide working lc_lock and lc_unlock functions.
2007-03-09 16:27:11 +00:00
{
panic("lockmgr locks do not support sleep interlocking");
}
Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. With current lock classes KPI it was really difficult because there was no way to pass an rmtracker object to the lock/unlock routines. In order to accomplish the task, modify the aforementioned functions so that they can return (or pass as argument) an uinptr_t, which is in the rm case used to hold a pointer to struct rm_priotracker for current thread. As an added bonus, this fixes rm_sleep() in the rm shared case, which right now can communicate priotracker structure between lc_unlock()/lc_lock(). Suggested by: jhb Reviewed by: jhb Approved by: re (delphij)
2013-09-20 23:06:21 +00:00
static uintptr_t
Add two new function pointers 'lc_lock' and 'lc_unlock' to lock classes. These functions are intended to be used to drop a lock and then reacquire it when doing an sleep such as msleep(9). Both functions accept a 'struct lock_object *' as their first parameter. The 'lc_unlock' function returns an integer that is then passed as the second paramter to the subsequent 'lc_lock' function. This can be used to communicate state. For example, sx locks and rwlocks use this to indicate if the lock was share/read locked vs exclusive/write locked. Currently, spin mutexes and lockmgr locks do not provide working lc_lock and lc_unlock functions.
2007-03-09 16:27:11 +00:00
unlock_lockmgr(struct lock_object *lock)
{
panic("lockmgr locks do not support sleep interlocking");
}
Add the OpenSolaris dtrace lockstat provider. The lockstat provider adds probes for mutexes, reader/writer and shared/exclusive locks to gather contention statistics and other locking information for dtrace scripts, the lockstat(1M) command and other potential consumers. Reviewed by: attilio jhb jb Approved by: gnn (mentor)
2009-05-26 20:28:22 +00:00
#ifdef KDTRACE_HOOKS
static int
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
owner_lockmgr(const struct lock_object *lock, struct thread **owner)
Add the OpenSolaris dtrace lockstat provider. The lockstat provider adds probes for mutexes, reader/writer and shared/exclusive locks to gather contention statistics and other locking information for dtrace scripts, the lockstat(1M) command and other potential consumers. Reviewed by: attilio jhb jb Approved by: gnn (mentor)
2009-05-26 20:28:22 +00:00
{
panic("lockmgr locks do not support owner inquiring");
}
#endif
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
void
lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags)
{
int iflags;
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
MPASS((flags & ~LK_INIT_MASK) == 0);
* Change the scope of the ASSERT_ATOMIC_LOAD() from a generic check to a pointer-fetching specific operation check. Consequently, rename the operation ASSERT_ATOMIC_LOAD_PTR(). * Fix the implementation of ASSERT_ATOMIC_LOAD_PTR() by checking directly alignment on the word boundry, for all the given specific architectures. That's a bit too strict for some common case, but it assures safety. * Add a comment explaining the scope of the macro * Add a new stub in the lockmgr specific implementation Tested by: marcel (initial version), marius Reviewed by: rwatson, jhb (comment specific review) Approved by: re (kib)
2009-08-17 16:17:21 +00:00
ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock,
("%s: lockmgr not aligned for %s: %p", __func__, wmesg,
&lk->lk_lock));
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Handle lock recursion differenty by always checking against LO_RECURSABLE instead the lock own flag itself. Tested by: pho
2009-06-02 13:03:35 +00:00
iflags = LO_SLEEPABLE | LO_UPGRADABLE;
if (flags & LK_CANRECURSE)
iflags |= LO_RECURSABLE;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if ((flags & LK_NODUP) == 0)
iflags |= LO_DUPOK;
if (flags & LK_NOPROFILE)
iflags |= LO_NOPROFILE;
if ((flags & LK_NOWITNESS) == 0)
iflags |= LO_WITNESS;
if (flags & LK_QUIET)
iflags |= LO_QUIET;
Add option WITNESS_NO_VNODE to suppress printing LORs between VNODE locks. To support this, VNODE locks are created with the LK_IS_VNODE flag. This flag is propagated down using the LO_IS_VNODE flag. Note that WITNESS still records the LOR. Only the printing and the optional entering into the kernel debugger is bypassed with the WITNESS_NO_VNODE option.
2013-05-09 16:28:18 +00:00
if (flags & LK_IS_VNODE)
iflags |= LO_IS_VNODE;
Add flag LK_NEW for lockinit() that is converted to LO_NEW and passed down to lock_init(). This allows for lockinit() on a not prezeroed memory.
2019-01-15 00:35:19 +00:00
if (flags & LK_NEW)
iflags |= LO_NEW;
lockmgr: remove more remnants of adaptive spinning Sponsored by: The FreeBSD Foundation
2019-12-01 00:35:08 +00:00
iflags |= flags & LK_NOSHARE;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
A few mostly cosmetic nits to aid in debugging: - Call lock_init() first before setting any lock_object fields in lock init routines. This way if the machine panics due to a duplicate init the lock's original state is preserved. - Somewhat similarly, don't decrement td_locks and td_slocks until after an unlock operation has completed successfully.
2013-06-25 20:23:08 +00:00
lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lk_lock = LK_UNLOCKED;
lk->lk_recurse = 0;
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
lk->lk_exslpfail = 0;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lk_timo = timo;
lk->lk_pri = pri;
STACK_ZERO(lk);
Fix kern_lock so that it will work. Additionally, clean-up some of the VM systems usage of the kernel lock (lockmgr) code. This is a first pass implementation, and is expected to evolve as needed. The API for the lock manager code has not changed, but the underlying implementation has changed significantly. This change should not materially affect our current SMP or UP code without non-standard parameters being used.
1997-08-18 02:06:35 +00:00
}
Add dedicated routines to toggle lockmgr flags such as LK_NOSHARE and LK_CANRECURSE after a lock is created. Use them to implement macros that otherwise manipulated the flags directly. Assert that the associated lockmgr lock is exclusively locked by the current thread when manipulating these flags to ensure the flag updates are safe. This last change required some minor shuffling in a few filesystems to exclusively lock a brand new vnode slightly earlier. Reviewed by: kib MFC after: 3 days
2010-08-20 19:46:50 +00:00
/*
* XXX: Gross hacks to manipulate external lock flags after
* initialization. Used for certain vnode and buf locks.
*/
void
lockallowshare(struct lock *lk)
{
lockmgr_assert(lk, KA_XLOCKED);
lk->lock_object.lo_flags &= ~LK_NOSHARE;
}
Add function and wrapper to switch lockmgr and vnode lock back to auto-promotion of shared to exclusive. Tested by: hrs, pho Sponsored by: The FreeBSD Foundation MFC after: 1 week
2014-08-29 09:02:01 +00:00
void
lockdisableshare(struct lock *lk)
{
lockmgr_assert(lk, KA_XLOCKED);
lk->lock_object.lo_flags |= LK_NOSHARE;
}
Add dedicated routines to toggle lockmgr flags such as LK_NOSHARE and LK_CANRECURSE after a lock is created. Use them to implement macros that otherwise manipulated the flags directly. Assert that the associated lockmgr lock is exclusively locked by the current thread when manipulating these flags to ensure the flag updates are safe. This last change required some minor shuffling in a few filesystems to exclusively lock a brand new vnode slightly earlier. Reviewed by: kib MFC after: 3 days
2010-08-20 19:46:50 +00:00
void
lockallowrecurse(struct lock *lk)
{
lockmgr_assert(lk, KA_XLOCKED);
lk->lock_object.lo_flags |= LO_RECURSABLE;
}
void
lockdisablerecurse(struct lock *lk)
{
lockmgr_assert(lk, KA_XLOCKED);
lk->lock_object.lo_flags &= ~LO_RECURSABLE;
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
void
lockdestroy(struct lock *lk)
{
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held"));
KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed"));
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
KASSERT(lk->lk_exslpfail == 0, ("lockmgr still exclusive waiters"));
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lock_destroy(&lk->lock_object);
Fix kern_lock so that it will work. Additionally, clean-up some of the VM systems usage of the kernel lock (lockmgr) code. This is a first pass implementation, and is expected to evolve as needed. The API for the lock manager code has not changed, but the underlying implementation has changed significantly. This change should not materially affect our current SMP or UP code without non-standard parameters being used.
1997-08-18 02:06:35 +00:00
}
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
static bool __always_inline
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags, bool fp)
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
{
/*
* If no other thread has an exclusive lock, or
* no exclusive waiter is present, bump the count of
* sharers. Since we have to preserve the state of
* waiters, if we fail to acquire the shared lock
* loop back and retry.
*/
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
while (LK_CAN_SHARE(*xp, flags, fp)) {
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
if (atomic_fcmpset_acq_ptr(&lk->lk_lock, xp,
*xp + LK_ONE_SHARER)) {
return (true);
}
}
return (false);
}
static bool __always_inline
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp)
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
{
for (;;) {
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
if (LK_SHARERS(*xp) > 1 || !(*xp & LK_ALL_WAITERS)) {
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
if (atomic_fcmpset_rel_ptr(&lk->lk_lock, xp,
*xp - LK_ONE_SHARER))
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
return (true);
continue;
}
break;
}
return (false);
}
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
static bool
lockmgr_slock_adaptive(struct lock_delay_arg *lda, struct lock *lk, uintptr_t *xp,
int flags)
{
struct thread *owner;
uintptr_t x;
x = *xp;
MPASS(x != LK_UNLOCKED);
owner = (struct thread *)LK_HOLDER(x);
for (;;) {
MPASS(owner != curthread);
if (owner == (struct thread *)LK_KERNPROC)
return (false);
if ((x & LK_SHARE) && LK_SHARERS(x) > 0)
return (false);
if (owner == NULL)
return (false);
if (!TD_IS_RUNNING(owner))
return (false);
if ((x & LK_ALL_WAITERS) != 0)
return (false);
lock_delay(lda);
x = lockmgr_read_value(lk);
if (LK_CAN_SHARE(x, flags, false)) {
*xp = x;
return (true);
}
owner = (struct thread *)LK_HOLDER(x);
}
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
static __noinline int
lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *file, int line, struct lockmgr_wait *lwa)
{
uintptr_t tid, x;
int error = 0;
const char *iwmesg;
int ipri, itimo;
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
uint64_t sleep_time = 0;
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
#ifdef LOCK_PROFILING
uint64_t waittime = 0;
int contested = 0;
#endif
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
struct lock_delay_arg lda;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
tid = (uintptr_t)curthread;
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
file, line, flags & LK_INTERLOCK ? ilk : NULL);
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
lock_delay_arg_init(&lda, &lockmgr_delay);
if (!lk_adaptive)
flags &= ~LK_ADAPTIVE;
x = lockmgr_read_value(lk);
/*
* The lock may already be locked exclusive by curthread,
* avoid deadlock.
*/
if (LK_HOLDER(x) == tid) {
LOCK_LOG2(lk,
"%s: %p already held in exclusive mode",
__func__, lk);
error = EDEADLK;
goto out;
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
for (;;) {
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
if (lockmgr_slock_try(lk, &x, flags, false))
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
break;
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
if ((flags & (LK_ADAPTIVE | LK_INTERLOCK)) == LK_ADAPTIVE) {
if (lockmgr_slock_adaptive(&lda, lk, &x, flags))
continue;
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
#endif
lock_profile_obtain_lock_failed(&lk->lock_object,
&contested, &waittime);
/*
* If the lock is expected to not sleep just give up
* and return.
*/
if (LK_TRYOP(flags)) {
LOCK_LOG2(lk, "%s: %p fails the try operation",
__func__, lk);
error = EBUSY;
break;
}
/*
* Acquire the sleepqueue chain lock because we
* probabilly will need to manipulate waiters flags.
*/
sleepq_lock(&lk->lock_object);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
retry_sleepq:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
/*
* if the lock can be acquired in shared mode, try
* again.
*/
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
if (LK_CAN_SHARE(x, flags, false)) {
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
sleepq_release(&lk->lock_object);
continue;
}
/*
* Try to set the LK_SHARED_WAITERS flag. If we fail,
* loop back and retry.
*/
if ((x & LK_SHARED_WAITERS) == 0) {
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
if (!atomic_fcmpset_acq_ptr(&lk->lk_lock, &x,
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
x | LK_SHARED_WAITERS)) {
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
goto retry_sleepq;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
LOCK_LOG2(lk, "%s: %p set shared waiters flag",
__func__, lk);
}
if (lwa == NULL) {
iwmesg = lk->lock_object.lo_name;
ipri = lk->lk_pri;
itimo = lk->lk_timo;
} else {
iwmesg = lwa->iwmesg;
ipri = lwa->ipri;
itimo = lwa->itimo;
}
/*
* As far as we have been unable to acquire the
* shared lock and the shared waiters flag is set,
* we will sleep.
*/
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
sleep_time -= lockstat_nsecs(&lk->lock_object);
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
SQ_SHARED_QUEUE);
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
sleep_time += lockstat_nsecs(&lk->lock_object);
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
flags &= ~LK_INTERLOCK;
if (error) {
LOCK_LOG3(lk,
"%s: interrupted sleep for %p with %d",
__func__, lk, error);
break;
}
LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
__func__, lk);
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
x = lockmgr_read_value(lk);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
if (error == 0) {
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
if (sleep_time != 0)
LOCKSTAT_RECORD4(lockmgr__block, lk, sleep_time,
LOCKSTAT_READER, (x & LK_SHARE) == 0,
(x & LK_SHARE) == 0 ? 0 : LK_SHARERS(x));
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
#ifdef LOCK_PROFILING
lockmgr_note_shared_acquire(lk, contested, waittime,
file, line, flags);
#else
lockmgr_note_shared_acquire(lk, 0, 0, file, line,
flags);
#endif
}
out:
lockmgr_exit(flags, ilk, 0);
return (error);
}
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
static bool
lockmgr_xlock_adaptive(struct lock_delay_arg *lda, struct lock *lk, uintptr_t *xp)
{
struct thread *owner;
uintptr_t x;
x = *xp;
MPASS(x != LK_UNLOCKED);
owner = (struct thread *)LK_HOLDER(x);
for (;;) {
MPASS(owner != curthread);
if (owner == NULL)
return (false);
if ((x & LK_SHARE) && LK_SHARERS(x) > 0)
return (false);
if (owner == (struct thread *)LK_KERNPROC)
return (false);
if (!TD_IS_RUNNING(owner))
return (false);
if ((x & LK_ALL_WAITERS) != 0)
return (false);
lock_delay(lda);
x = lockmgr_read_value(lk);
if (x == LK_UNLOCKED) {
*xp = x;
return (true);
}
owner = (struct thread *)LK_HOLDER(x);
}
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
static __noinline int
lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *file, int line, struct lockmgr_wait *lwa)
{
struct lock_class *class;
uintptr_t tid, x, v;
int error = 0;
const char *iwmesg;
int ipri, itimo;
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
uint64_t sleep_time = 0;
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
#ifdef LOCK_PROFILING
uint64_t waittime = 0;
int contested = 0;
#endif
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
struct lock_delay_arg lda;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
tid = (uintptr_t)curthread;
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
ilk : NULL);
/*
* If curthread already holds the lock and this one is
* allowed to recurse, simply recurse on it.
*/
if (lockmgr_xlocked(lk)) {
if ((flags & LK_CANRECURSE) == 0 &&
(lk->lock_object.lo_flags & LO_RECURSABLE) == 0) {
/*
* If the lock is expected to not panic just
* give up and return.
*/
if (LK_TRYOP(flags)) {
LOCK_LOG2(lk,
"%s: %p fails the try operation",
__func__, lk);
error = EBUSY;
goto out;
}
if (flags & LK_INTERLOCK) {
class = LOCK_CLASS(ilk);
class->lc_unlock(ilk);
}
When running with a kernel compiled with DEBUG_LOCKS, before panic'ing for recusing on a non-recursive lock, print out the kernel stack where the lock was originally acquired.
2020-04-09 23:42:13 +00:00
STACK_PRINT(lk);
At this point iwmesg isn't initialized yet, so print pointer to lock rather than panic before panicing.
2018-03-20 22:05:21 +00:00
panic("%s: recursing on non recursive lockmgr %p "
"@ %s:%d\n", __func__, lk, file, line);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
lockmgr: denote recursion with a bit in lock value This reduces excessive reads from the lock. Tested by: pho
2020-07-21 14:42:22 +00:00
atomic_set_ptr(&lk->lk_lock, LK_WRITER_RECURSED);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
lk->lk_recurse++;
LOCK_LOG2(lk, "%s: %p recursing", __func__, lk);
LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
lk->lk_recurse, file, line);
WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
LK_TRYWIT(flags), file, line);
TD_LOCKS_INC(curthread);
goto out;
}
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
x = LK_UNLOCKED;
lock_delay_arg_init(&lda, &lockmgr_delay);
if (!lk_adaptive)
flags &= ~LK_ADAPTIVE;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
for (;;) {
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
if (x == LK_UNLOCKED) {
if (atomic_fcmpset_acq_ptr(&lk->lk_lock, &x, tid))
break;
lockmgr: add missing 'continue' to account for spuriously failed fcmpset PR: 248245 Reported by: gbe Noted by: markj Fixes by: r363415 ("lockmgr: add adaptive spinning")
2020-07-24 17:28:24 +00:00
continue;
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
}
if ((flags & (LK_ADAPTIVE | LK_INTERLOCK)) == LK_ADAPTIVE) {
if (lockmgr_xlock_adaptive(&lda, lk, &x))
continue;
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
#endif
lock_profile_obtain_lock_failed(&lk->lock_object,
&contested, &waittime);
/*
* If the lock is expected to not sleep just give up
* and return.
*/
if (LK_TRYOP(flags)) {
LOCK_LOG2(lk, "%s: %p fails the try operation",
__func__, lk);
error = EBUSY;
break;
}
/*
* Acquire the sleepqueue chain lock because we
* probabilly will need to manipulate waiters flags.
*/
sleepq_lock(&lk->lock_object);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
retry_sleepq:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
/*
* if the lock has been released while we spun on
* the sleepqueue chain lock just try again.
*/
if (x == LK_UNLOCKED) {
sleepq_release(&lk->lock_object);
continue;
}
/*
* The lock can be in the state where there is a
* pending queue of waiters, but still no owner.
* This happens when the lock is contested and an
* owner is going to claim the lock.
* If curthread is the one successfully acquiring it
* claim lock ownership and return, preserving waiters
* flags.
*/
v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
if ((x & ~v) == LK_UNLOCKED) {
v &= ~LK_EXCLUSIVE_SPINNERS;
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
if (atomic_fcmpset_acq_ptr(&lk->lk_lock, &x,
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
tid | v)) {
sleepq_release(&lk->lock_object);
LOCK_LOG2(lk,
"%s: %p claimed by a new writer",
__func__, lk);
break;
}
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
goto retry_sleepq;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
/*
* Try to set the LK_EXCLUSIVE_WAITERS flag. If we
* fail, loop back and retry.
*/
if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
if (!atomic_fcmpset_ptr(&lk->lk_lock, &x,
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
x | LK_EXCLUSIVE_WAITERS)) {
lockmgr: save on sleepq when cmpset fails
2018-03-05 00:30:07 +00:00
goto retry_sleepq;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
LOCK_LOG2(lk, "%s: %p set excl waiters flag",
__func__, lk);
}
if (lwa == NULL) {
iwmesg = lk->lock_object.lo_name;
ipri = lk->lk_pri;
itimo = lk->lk_timo;
} else {
iwmesg = lwa->iwmesg;
ipri = lwa->ipri;
itimo = lwa->itimo;
}
/*
* As far as we have been unable to acquire the
* exclusive lock and the exclusive waiters flag
* is set, we will sleep.
*/
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
sleep_time -= lockstat_nsecs(&lk->lock_object);
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
SQ_EXCLUSIVE_QUEUE);
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
sleep_time += lockstat_nsecs(&lk->lock_object);
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
flags &= ~LK_INTERLOCK;
if (error) {
LOCK_LOG3(lk,
"%s: interrupted sleep for %p with %d",
__func__, lk, error);
break;
}
LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
__func__, lk);
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
x = lockmgr_read_value(lk);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
if (error == 0) {
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
#ifdef KDTRACE_HOOKS
if (sleep_time != 0)
LOCKSTAT_RECORD4(lockmgr__block, lk, sleep_time,
LOCKSTAT_WRITER, (x & LK_SHARE) == 0,
(x & LK_SHARE) == 0 ? 0 : LK_SHARERS(x));
#endif
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
#ifdef LOCK_PROFILING
lockmgr_note_exclusive_acquire(lk, contested, waittime,
file, line, flags);
#else
lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
flags);
#endif
}
out:
lockmgr_exit(flags, ilk, 0);
return (error);
}
static __noinline int
lockmgr_upgrade(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *file, int line, struct lockmgr_wait *lwa)
{
lockmgr: rewrite upgrade to stop always dropping the lock This matches rw and sx locks.
2020-07-21 14:41:25 +00:00
uintptr_t tid, v, setv;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
int error = 0;
int op;
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
tid = (uintptr_t)curthread;
_lockmgr_assert(lk, KA_SLOCKED, file, line);
op = flags & LK_TYPE_MASK;
lockmgr: rewrite upgrade to stop always dropping the lock This matches rw and sx locks.
2020-07-21 14:41:25 +00:00
v = lockmgr_read_value(lk);
for (;;) {
if (LK_SHARERS_LOCK(v) > 1) {
if (op == LK_TRYUPGRADE) {
LOCK_LOG2(lk, "%s: %p failed the nowait upgrade",
__func__, lk);
error = EBUSY;
goto out;
}
if (lockmgr_sunlock_try(lk, &v)) {
lockmgr_note_shared_release(lk, file, line);
goto out_xlock;
}
}
MPASS((v & ~LK_ALL_WAITERS) == LK_SHARERS_LOCK(1));
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
lockmgr: rewrite upgrade to stop always dropping the lock This matches rw and sx locks.
2020-07-21 14:41:25 +00:00
setv = tid;
setv |= (v & LK_ALL_WAITERS);
/*
* Try to switch from one shared lock to an exclusive one.
* We need to preserve waiters flags during the operation.
*/
if (atomic_fcmpset_ptr(&lk->lk_lock, &v, setv)) {
LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file,
line);
WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE |
LK_TRYWIT(flags), file, line);
LOCKSTAT_RECORD0(lockmgr__upgrade, lk);
TD_SLOCKS_DEC(curthread);
goto out;
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
}
lockmgr: rewrite upgrade to stop always dropping the lock This matches rw and sx locks.
2020-07-21 14:41:25 +00:00
out_xlock:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
error = lockmgr_xlock_hard(lk, flags, ilk, file, line, lwa);
flags &= ~LK_INTERLOCK;
out:
lockmgr: rewrite upgrade to stop always dropping the lock This matches rw and sx locks.
2020-07-21 14:41:25 +00:00
lockmgr_exit(flags, ilk, 0);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (error);
}
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
int
lockmgr: rename lock_fast_path to lock_flags The routine is not much of a fast path and the flags name better describes its purpose.
2020-02-14 11:21:28 +00:00
lockmgr_lock_flags(struct lock *lk, u_int flags, struct lock_object *ilk,
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
const char *file, int line)
{
struct lock_class *class;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
uintptr_t x, tid;
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
u_int op;
bool locked;
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: Add missed neutering during panic r313683 introduced new lockmgr APIs that missed the panic-time neutering present in the rest of our locks. Correct that by adding the usual check. Additionally, move the __lockmgr_args neutering above the assertions at the top of the function. Drop the interlock unlock because we shouldn't have an unneutered interlock either. No point trying to unlock it. PR: 227749 Reported by: jtl Sponsored by: Dell EMC Isilon
2018-04-24 18:41:14 +00:00
return (0);
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
op = flags & LK_TYPE_MASK;
locked = false;
switch (op) {
case LK_SHARED:
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
file, line, flags & LK_INTERLOCK ? ilk : NULL);
if (__predict_false(lk->lock_object.lo_flags & LK_NOSHARE))
break;
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
x = lockmgr_read_value(lk);
lockmgr: tidy up slock/sunlock similar to other locks
2018-07-13 22:40:14 +00:00
if (lockmgr_slock_try(lk, &x, flags, true)) {
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
lockmgr_note_shared_acquire(lk, 0, 0,
file, line, flags);
locked = true;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
} else {
return (lockmgr_slock_hard(lk, flags, ilk, file, line,
NULL));
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
}
break;
case LK_EXCLUSIVE:
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
ilk : NULL);
tid = (uintptr_t)curthread;
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
if (lockmgr_read_value(lk) == LK_UNLOCKED &&
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
flags);
locked = true;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
} else {
return (lockmgr_xlock_hard(lk, flags, ilk, file, line,
NULL));
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
}
break;
case LK_UPGRADE:
case LK_TRYUPGRADE:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (lockmgr_upgrade(lk, flags, ilk, file, line, NULL));
lockmgr: implement fast path The main lockmgr routine takes 8 arguments which makes it impossible to tail-call it by the intermediate vop_stdlock/unlock routines. The routine itself starts with an if-forest and reads from the lock itself several times. This slows things down both single- and multi-threaded. With the patch single-threaded fstats go 4% up and multithreaded up to ~27%. Note that there is still a lot of room for improvement. Reviewed by: kib Tested by: pho
2017-02-12 09:49:44 +00:00
default:
break;
}
if (__predict_true(locked)) {
if (__predict_false(flags & LK_INTERLOCK)) {
class = LOCK_CLASS(ilk);
class->lc_unlock(ilk);
}
return (0);
} else {
return (__lockmgr_args(lk, flags, ilk, LK_WMESG_DEFAULT,
LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, file, line));
}
}
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
static __noinline int
lockmgr_sunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_object *ilk,
const char *file, int line)
{
int wakeup_swapper = 0;
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
wakeup_swapper = wakeupshlk(lk, file, line);
out:
lockmgr_exit(flags, ilk, wakeup_swapper);
return (0);
}
static __noinline int
lockmgr_xunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_object *ilk,
const char *file, int line)
{
uintptr_t tid, v;
int wakeup_swapper = 0;
u_int realexslp;
int queue;
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
tid = (uintptr_t)curthread;
/*
* As first option, treact the lock as if it has not
* any waiter.
* Fix-up the tid var if the lock has been disowned.
*/
if (LK_HOLDER(x) == LK_KERNPROC)
tid = LK_KERNPROC;
/*
* The lock is held in exclusive mode.
* If the lock is recursed also, then unrecurse it.
*/
lockmgr: denote recursion with a bit in lock value This reduces excessive reads from the lock. Tested by: pho
2020-07-21 14:42:22 +00:00
if (lockmgr_recursed_v(x)) {
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
LOCK_LOG2(lk, "%s: %p unrecursing", __func__, lk);
lk->lk_recurse--;
lockmgr: denote recursion with a bit in lock value This reduces excessive reads from the lock. Tested by: pho
2020-07-21 14:42:22 +00:00
if (lk->lk_recurse == 0)
atomic_clear_ptr(&lk->lk_lock, LK_WRITER_RECURSED);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
}
if (tid != LK_KERNPROC)
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk,
LOCKSTAT_WRITER);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
lockmgr: avoid atomic on unlock in the slow path The code is pretty much guaranteed not to be able to unlock. This is a minor nit. The code still performs way too many reads. The altered exclusive-locked condition is supposed to be always true as well, to be cleaned up at a later date.
2018-05-18 22:57:52 +00:00
if (x == tid && atomic_cmpset_rel_ptr(&lk->lk_lock, tid, LK_UNLOCKED))
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
goto out;
sleepq_lock(&lk->lock_object);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
v = LK_UNLOCKED;
/*
* If the lock has exclusive waiters, give them
* preference in order to avoid deadlock with
* shared runners up.
* If interruptible sleeps left the exclusive queue
* empty avoid a starvation for the threads sleeping
* on the shared queue by giving them precedence
* and cleaning up the exclusive waiters bit anyway.
* Please note that lk_exslpfail count may be lying
* about the real number of waiters with the
* LK_SLEEPFAIL flag on because they may be used in
* conjunction with interruptible sleeps so
* lk_exslpfail might be considered an 'upper limit'
* bound, including the edge cases.
*/
MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
realexslp = sleepq_sleepcnt(&lk->lock_object, SQ_EXCLUSIVE_QUEUE);
if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
if (lk->lk_exslpfail < realexslp) {
lk->lk_exslpfail = 0;
queue = SQ_EXCLUSIVE_QUEUE;
v |= (x & LK_SHARED_WAITERS);
} else {
lk->lk_exslpfail = 0;
LOCK_LOG2(lk,
"%s: %p has only LK_SLEEPFAIL sleepers",
__func__, lk);
LOCK_LOG2(lk,
"%s: %p waking up threads on the exclusive queue",
__func__, lk);
wakeup_swapper = sleepq_broadcast(&lk->lock_object,
SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
queue = SQ_SHARED_QUEUE;
}
} else {
/*
* Exclusive waiters sleeping with LK_SLEEPFAIL
* on and using interruptible sleeps/timeout
* may have left spourious lk_exslpfail counts
* on, so clean it up anyway.
*/
lk->lk_exslpfail = 0;
queue = SQ_SHARED_QUEUE;
}
LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
__func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
"exclusive");
atomic_store_rel_ptr(&lk->lk_lock, v);
wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK, 0, queue);
sleepq_release(&lk->lock_object);
out:
lockmgr_exit(flags, ilk, wakeup_swapper);
return (0);
}
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
/*
* Lightweight entry points for common operations.
*
* Functionality is similar to sx locks, in that none of the additional lockmgr
* features are supported. To be clear, these are NOT supported:
* 1. shared locking disablement
* 2. returning with an error after sleep
* 3. unlocking the interlock
*
lockmgr: rename lock_fast_path to lock_flags The routine is not much of a fast path and the flags name better describes its purpose.
2020-02-14 11:21:28 +00:00
* If in doubt, use lockmgr_lock_flags.
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
*/
int
lockmgr_slock(struct lock *lk, u_int flags, const char *file, int line)
{
uintptr_t x;
MPASS((flags & LK_TYPE_MASK) == LK_SHARED);
MPASS((flags & LK_INTERLOCK) == 0);
MPASS((lk->lock_object.lo_flags & LK_NOSHARE) == 0);
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
file, line, NULL);
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
x = lockmgr_read_value(lk);
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
if (__predict_true(lockmgr_slock_try(lk, &x, flags, true))) {
lockmgr_note_shared_acquire(lk, 0, 0, file, line, flags);
return (0);
}
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
return (lockmgr_slock_hard(lk, flags | LK_ADAPTIVE, NULL, file, line, NULL));
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
}
int
lockmgr_xlock(struct lock *lk, u_int flags, const char *file, int line)
{
uintptr_t tid;
MPASS((flags & LK_TYPE_MASK) == LK_EXCLUSIVE);
MPASS((flags & LK_INTERLOCK) == 0);
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
LOP_EXCLUSIVE, file, line, NULL);
tid = (uintptr_t)curthread;
if (atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
flags);
return (0);
}
lockmgr: add adaptive spinning It is very conservative. Only spinning when LK_ADAPTIVE is passed, only on exclusive lock and never when any waiters are present. buffer cache is remains not spinning. This reduces total sleep times during buildworld etc., but it does not shorten total real time (culprits are contention in the vm subsystem along with slock + upgrade which is not covered). For microbenchmarks: open3_processes -t 52 (open/close of the same file for writing) ops/s: before: 258845 after: 801638 Reviewed by: kib Tested by: pho Differential Revision: https://reviews.freebsd.org/D25753
2020-07-22 12:30:31 +00:00
return (lockmgr_xlock_hard(lk, flags | LK_ADAPTIVE, NULL, file, line, NULL));
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
}
int
lockmgr_unlock(struct lock *lk)
{
uintptr_t x, tid;
const char *file;
int line;
file = __FILE__;
line = __LINE__;
_lockmgr_assert(lk, KA_LOCKED, file, line);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
if (__predict_true(x & LK_SHARE) != 0) {
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
lockmgr_note_shared_release(lk, file, line);
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
if (lockmgr_sunlock_try(lk, &x)) {
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk, LOCKSTAT_READER);
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
} else {
return (lockmgr_sunlock_hard(lk, x, LK_RELEASE, NULL, file, line));
}
} else {
tid = (uintptr_t)curthread;
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
lockmgr_note_exclusive_release(lk, file, line);
lockmgr: denote recursion with a bit in lock value This reduces excessive reads from the lock. Tested by: pho
2020-07-21 14:42:22 +00:00
if (x == tid && atomic_cmpset_rel_ptr(&lk->lk_lock, tid, LK_UNLOCKED)) {
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk,LOCKSTAT_WRITER);
vfs: locking primitives which elide ->v_vnlock and shared locking disablement Both of these features are not needed by many consumers and result in avoidable reads which in turn puts them on profiles due to cache-line ping ponging. On top of that the current lockgmr entry point is slower than necessary single-threaded. As an attempted clean up preparing for other changes, provide new routines which don't support any of the aforementioned features. With these patches in place vop_stdlock and vop_stdunlock disappear from flamegraphs during -j 104 buildkernel. Reviewed by: jeff (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D22665
2019-12-11 23:11:21 +00:00
} else {
return (lockmgr_xunlock_hard(lk, x, LK_RELEASE, NULL, file, line));
}
}
return (0);
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
int
__lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *wmesg, int pri, int timo, const char *file, int line)
- Do not use APAUSE if LK_INTERLOCK is set. We lose synchronization if the lockmgr interlock is dropped after the caller's interlock is dropped. - Change some lockmgr KTRs to be slightly more helpful. Sponsored By: Isilon Systems, Inc.
2005-01-24 10:20:59 +00:00
{
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
GIANT_DECLARE;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
struct lockmgr_wait lwa;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
struct lock_class *class;
- Introduce lockmgr_args() in the lockmgr space. This function performs the same operation of lockmgr() but accepting a custom wmesg, prio and timo for the particular lock instance, overriding default values lkp->lk_wmesg, lkp->lk_prio and lkp->lk_timo. - Use lockmgr_args() in order to implement BUF_TIMELOCK() - Cleanup BUF_LOCK() - Remove LK_INTERNAL as it is nomore used in the lockmgr namespace Tested by: Andrea Barberio <insomniac at slackware dot it>
2008-02-15 21:04:36 +00:00
const char *iwmesg;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
uintptr_t tid, v, x;
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
u_int op, realexslp;
- Wrap lock profiling state variables in #ifdef LOCK_PROFILING blocks.
2009-03-15 08:03:54 +00:00
int error, ipri, itimo, queue, wakeup_swapper;
#ifdef LOCK_PROFILING
uint64_t waittime = 0;
int contested = 0;
#endif
- Introduce lockmgr_args() in the lockmgr space. This function performs the same operation of lockmgr() but accepting a custom wmesg, prio and timo for the particular lock instance, overriding default values lkp->lk_wmesg, lkp->lk_prio and lkp->lk_timo. - Use lockmgr_args() in order to implement BUF_TIMELOCK() - Cleanup BUF_LOCK() - Remove LK_INTERNAL as it is nomore used in the lockmgr namespace Tested by: Andrea Barberio <insomniac at slackware dot it>
2008-02-15 21:04:36 +00:00
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
lockmgr: Add missed neutering during panic r313683 introduced new lockmgr APIs that missed the panic-time neutering present in the rest of our locks. Correct that by adding the usual check. Additionally, move the __lockmgr_args neutering above the assertions at the top of the function. Drop the interlock unlock because we shouldn't have an unneutered interlock either. No point trying to unlock it. PR: 227749 Reported by: jtl Sponsored by: Dell EMC Isilon
2018-04-24 18:41:14 +00:00
return (0);
- Slightly restructure acquire() so I can add more ktr information and an assert to help find two strange bugs. - Remove some nearby spls.
2005-04-03 11:49:02 +00:00
error = 0;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
tid = (uintptr_t)curthread;
op = (flags & LK_TYPE_MASK);
iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg;
ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri;
itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo;
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
lwa.iwmesg = iwmesg;
lwa.ipri = ipri;
lwa.itimo = itimo;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
MPASS((flags & ~LK_TOTAL_MASK) == 0);
- Remove a stale comment. - Add an extra assertion in order to catch malformed requested operations.
2008-04-12 13:56:17 +00:00
KASSERT((op & (op - 1)) == 0,
("%s: Invalid requested operation @ %s:%d", __func__, file, line));
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 ||
(op != LK_DOWNGRADE && op != LK_RELEASE),
("%s: Invalid flags in regard of the operation desired @ %s:%d",
__func__, file, line));
KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL,
("%s: LK_INTERLOCK passed without valid interlock @ %s:%d",
__func__, file, line));
Fixup r240424: On entering KDB backends, the hijacked thread to run interrupt context can still be idlethread. At that point, without the panic condition, it can still happen that idlethread then will try to acquire some locks to carry on some operations. Skip the idlethread check on block/sleep lock operations when KDB is active. Reported by: jh Tested by: jh MFC after: 1 week
2012-12-22 09:37:34 +00:00
KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
Improve check coverage about idle threads. Idle threads are not allowed to acquire any lock but spinlocks. Deny any attempt to do so by panicing at the locking operation when INVARIANTS is on. Then, remove the check on blocking on a turnstile. The check in sleepqueues is left because they are not allowed to use tsleep() either which could happen still. Reviewed by: bde, jhb, kib MFC after: 1 week
2012-09-12 22:10:53 +00:00
("%s: idle thread %p on lockmgr %s @ %s:%d", __func__, curthread,
lk->lock_object.lo_name, file, line));
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
Fix kern_lock so that it will work. Additionally, clean-up some of the VM systems usage of the kernel lock (lockmgr) code. This is a first pass implementation, and is expected to evolve as needed. The API for the lock manager code has not changed, but the underlying implementation has changed significantly. This change should not materially affect our current SMP or UP code without non-standard parameters being used.
1997-08-18 02:06:35 +00:00
Fix the LK_NOSHARE lockmgr flag interaction with LK_UPGRADE and LK_DOWNGRADE lock ops. Namely, the ops should be NOP since LK_NOSHARE locks are always exclusive. Reported by: rmacklem Reviewed by: attilio Tested by: pho Approved by: re (kensmith) MFC after: 1 week
2011-08-01 19:07:03 +00:00
if (lk->lock_object.lo_flags & LK_NOSHARE) {
switch (op) {
case LK_SHARED:
op = LK_EXCLUSIVE;
break;
case LK_UPGRADE:
Add LK_TRYUPGRADE operation for lockmgr(9), which attempts to atomically upgrade shared lock to exclusive. On failure, error is returned and lock is not dropped in the process. Tested by: pho (previous version) No objections from: attilio Sponsored by: The FreeBSD Foundation MFC after: 1 week Approved by: re (glebius)
2013-09-29 18:02:23 +00:00
case LK_TRYUPGRADE:
Fix the LK_NOSHARE lockmgr flag interaction with LK_UPGRADE and LK_DOWNGRADE lock ops. Namely, the ops should be NOP since LK_NOSHARE locks are always exclusive. Reported by: rmacklem Reviewed by: attilio Tested by: pho Approved by: re (kensmith) MFC after: 1 week
2011-08-01 19:07:03 +00:00
case LK_DOWNGRADE:
_lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED,
file, line);
lockmgr: unlock interlock (if requested) when dealing with upgrade/downgrade requests for LK_NOSHARE locks, just like for shared locks. PR: kern/174969 Reviewed by: attilio MFC after: 1 week
2013-01-06 21:47:59 +00:00
if (flags & LK_INTERLOCK)
class->lc_unlock(ilk);
Fix the LK_NOSHARE lockmgr flag interaction with LK_UPGRADE and LK_DOWNGRADE lock ops. Namely, the ops should be NOP since LK_NOSHARE locks are always exclusive. Reported by: rmacklem Reviewed by: attilio Tested by: pho Approved by: re (kensmith) MFC after: 1 week
2011-08-01 19:07:03 +00:00
return (0);
}
}
MUTEX_PROFILING has been generalized to LOCK_PROFILING. We now profile wait (time waited to acquire) and hold times for *all* kernel locks. If the architecture has a system synchronized TSC, the profiling code will use that - thereby minimizing profiling overhead. Large chunks of profiling code have been moved out of line, the overhead measured on the T1 for when it is compiled in but not enabled is < 1%. Approved by: scottl (standing in for mentor rwatson) Reviewed by: des and jhb
2006-11-11 03:18:07 +00:00
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
wakeup_swapper = 0;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
switch (op) {
case LK_SHARED:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (lockmgr_slock_hard(lk, flags, ilk, file, line, &lwa));
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
break;
case LK_UPGRADE:
Add LK_TRYUPGRADE operation for lockmgr(9), which attempts to atomically upgrade shared lock to exclusive. On failure, error is returned and lock is not dropped in the process. Tested by: pho (previous version) No objections from: attilio Sponsored by: The FreeBSD Foundation MFC after: 1 week Approved by: re (glebius)
2013-09-29 18:02:23 +00:00
case LK_TRYUPGRADE:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (lockmgr_upgrade(lk, flags, ilk, file, line, &lwa));
break;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
case LK_EXCLUSIVE:
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (lockmgr_xlock_hard(lk, flags, ilk, file, line, &lwa));
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
break;
case LK_DOWNGRADE:
Check for lockmgr recursion in case of disown and downgrade and panic also in !debugging kernel rather than having "undefined" behaviour. Tested by: avg MFC after: 1 week
2012-12-05 15:11:01 +00:00
_lockmgr_assert(lk, KA_XLOCKED, file, line);
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line);
Check for lockmgr recursion in case of disown and downgrade and panic also in !debugging kernel rather than having "undefined" behaviour. Tested by: avg MFC after: 1 week
2012-12-05 15:11:01 +00:00
/*
* Panic if the lock is recursed.
*/
if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) {
if (flags & LK_INTERLOCK)
class->lc_unlock(ilk);
panic("%s: downgrade a recursed lockmgr %s @ %s:%d\n",
__func__, iwmesg, file, line);
}
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
TD_SLOCKS_INC(curthread);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
/*
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* In order to preserve waiters flags, just spin.
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
*/
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
for (;;) {
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
x &= LK_ALL_WAITERS;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
LK_SHARERS_LOCK(1) | x))
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
break;
cpu_spinwait();
}
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
LOCKSTAT_RECORD0(lockmgr__downgrade, lk);
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
break;
case LK_RELEASE:
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
_lockmgr_assert(lk, KA_LOCKED, file, line);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
if (__predict_true(x & LK_SHARE) != 0) {
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
lockmgr_note_shared_release(lk, file, line);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (lockmgr_sunlock_hard(lk, x, flags, ilk, file, line));
} else {
lockmgr: don't touch the lock past unlock This evens it up with other locking primitives. Note lock profiling still touches the lock, which again is in line with the rest. Reviewed by: jeff Differential Revision: https://reviews.freebsd.org/D23343
2020-01-24 07:42:57 +00:00
lockmgr_note_exclusive_release(lk, file, line);
lockmgr: start decomposing the main routine The main routine takes 8 args, 3 of which are almost the same for most uses. This in particular pushes it above the limit of 6 arguments passable through registers on amd64 making it impossible to tail call. This is a prerequisite for further cleanups. Tested by: pho
2018-03-04 19:12:54 +00:00
return (lockmgr_xunlock_hard(lk, x, flags, ilk, file, line));
}
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
break;
case LK_DRAIN:
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
if (LK_CAN_WITNESS(flags))
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
- Fix a couple of inverted panic messages for shared/exclusive mismatches of a lock within a single thread. - Fix handling of interlocks in WITNESS by properly requiring the interlock to be held exactly once if it is specified.
2013-06-03 17:41:11 +00:00
LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
ilk : NULL);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
/*
s/alredy/already/ in the comments and the log message.
2008-07-25 11:22:25 +00:00
* Trying to drain a lock we already own will result in a
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
* deadlock.
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
*/
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (lockmgr_xlocked(lk)) {
if (flags & LK_INTERLOCK)
class->lc_unlock(ilk);
panic("%s: draining %s with the lock held @ %s:%d\n",
__func__, iwmesg, file, line);
}
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Microoptimize locking primitives by avoiding unnecessary atomic ops. Inline version of primitives do an atomic op and if it fails they fallback to actual primitives, which immediately retry the atomic op. The obvious optimisation is to check if the lock is free and only then proceed to do an atomic op. Reviewed by: jhb, vangyzen
2016-06-01 18:32:20 +00:00
for (;;) {
if (lk->lk_lock == LK_UNLOCKED &&
atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid))
break;
Add software PMC support. New kernel events can be added at various location for sampling or counting. This will for example allow easy system profiling whatever the processor is with known tools like pmcstat(8). Simultaneous usage of software PMC and hardware PMC is possible, for example looking at the lock acquire failure, page fault while sampling on instructions. Sponsored by: NETASQ MFC after: 1 month
2012-03-28 20:58:30 +00:00
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
#endif
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lock_profile_obtain_lock_failed(&lk->lock_object,
&contested, &waittime);
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* If the lock is expected to not sleep just give up
* and return.
*/
if (LK_TRYOP(flags)) {
LOCK_LOG2(lk, "%s: %p fails the try operation",
__func__, lk);
error = EBUSY;
break;
}
- Introduce lockmgr_args() in the lockmgr space. This function performs the same operation of lockmgr() but accepting a custom wmesg, prio and timo for the particular lock instance, overriding default values lkp->lk_wmesg, lkp->lk_prio and lkp->lk_timo. - Use lockmgr_args() in order to implement BUF_TIMELOCK() - Cleanup BUF_LOCK() - Remove LK_INTERNAL as it is nomore used in the lockmgr namespace Tested by: Andrea Barberio <insomniac at slackware dot it>
2008-02-15 21:04:36 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* Acquire the sleepqueue chain lock because we
* probabilly will need to manipulate waiters flags.
*/
sleepq_lock(&lk->lock_object);
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* if the lock has been released while we spun on
* the sleepqueue chain lock just try again.
*/
if (x == LK_UNLOCKED) {
sleepq_release(&lk->lock_object);
continue;
}
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
if ((x & ~v) == LK_UNLOCKED) {
v = (x & ~LK_EXCLUSIVE_SPINNERS);
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
/*
* If interruptible sleeps left the exclusive
* queue empty avoid a starvation for the
* threads sleeping on the shared queue by
* giving them precedence and cleaning up the
* exclusive waiters bit anyway.
Tweak comments.
2010-01-07 01:19:01 +00:00
* Please note that lk_exslpfail count may be
* lying about the real number of waiters with
* the LK_SLEEPFAIL flag on because they may
sys/kern: spelling fixes in comments. No functional change.
2016-04-29 22:15:33 +00:00
* be used in conjunction with interruptible
Fix typos.
2010-01-07 01:24:09 +00:00
* sleeps so lk_exslpfail might be considered
* an 'upper limit' bound, including the edge
Tweak comments.
2010-01-07 01:19:01 +00:00
* cases.
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
*/
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (v & LK_EXCLUSIVE_WAITERS) {
queue = SQ_EXCLUSIVE_QUEUE;
v &= ~LK_EXCLUSIVE_WAITERS;
} else {
Exclusive waiters sleeping with LK_SLEEPFAIL on and using interruptible sleeps/timeout may have left spourious lk_exslpfail counts on, so clean it up even when accessing a shared queue acquisition, giving to lk_exslpfail the value of 'upper limit'. In the worst case scenario, infact (mixed interruptible sleep / LK_SLEEPFAIL waiters) what may happen is that both queues are awaken even if that's not necessary, but still no harm. Reported by: Lucius Windschuh <lwindschuh at googlemail dot com> Reviewed by: kib Tested by: pho, Lucius Windschuh <lwindschuh at googlemail dot com>
2010-01-07 00:47:50 +00:00
/*
* Exclusive waiters sleeping with
* LK_SLEEPFAIL on and using
* interruptible sleeps/timeout may
* have left spourious lk_exslpfail
* counts on, so clean it up anyway.
*/
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
MPASS(v & LK_SHARED_WAITERS);
Exclusive waiters sleeping with LK_SLEEPFAIL on and using interruptible sleeps/timeout may have left spourious lk_exslpfail counts on, so clean it up even when accessing a shared queue acquisition, giving to lk_exslpfail the value of 'upper limit'. In the worst case scenario, infact (mixed interruptible sleep / LK_SLEEPFAIL waiters) what may happen is that both queues are awaken even if that's not necessary, but still no harm. Reported by: Lucius Windschuh <lwindschuh at googlemail dot com> Reviewed by: kib Tested by: pho, Lucius Windschuh <lwindschuh at googlemail dot com>
2010-01-07 00:47:50 +00:00
lk->lk_exslpfail = 0;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
queue = SQ_SHARED_QUEUE;
v &= ~LK_SHARED_WAITERS;
}
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively. A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect). In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues. The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping. Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
2009-12-12 21:31:07 +00:00
if (queue == SQ_EXCLUSIVE_QUEUE) {
realexslp =
sleepq_sleepcnt(&lk->lock_object,
SQ_EXCLUSIVE_QUEUE);
if (lk->lk_exslpfail >= realexslp) {
lk->lk_exslpfail = 0;
queue = SQ_SHARED_QUEUE;
v &= ~LK_SHARED_WAITERS;
if (realexslp != 0) {
LOCK_LOG2(lk,
"%s: %p has only LK_SLEEPFAIL sleepers",
__func__, lk);
LOCK_LOG2(lk,
"%s: %p waking up threads on the exclusive queue",
__func__, lk);
wakeup_swapper =
sleepq_broadcast(
&lk->lock_object,
SLEEPQ_LK, 0,
SQ_EXCLUSIVE_QUEUE);
}
} else
lk->lk_exslpfail = 0;
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) {
sleepq_release(&lk->lock_object);
continue;
}
LOCK_LOG3(lk,
"%s: %p waking up all threads on the %s queue",
__func__, lk, queue == SQ_SHARED_QUEUE ?
"shared" : "exclusive");
Use |= rather than += when aggregrating requests to wakeup the swapper. What we really want is an inclusive or of all the requests, and += can in theory roll over to 0.
2008-08-22 16:14:23 +00:00
wakeup_swapper |= sleepq_broadcast(
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
&lk->lock_object, SLEEPQ_LK, 0, queue);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* If shared waiters have been woken up we need
* to wait for one of them to acquire the lock
* before to set the exclusive waiters in
* order to avoid a deadlock.
*/
if (queue == SQ_SHARED_QUEUE) {
for (v = lk->lk_lock;
(v & LK_SHARE) && !LK_SHARERS(v);
v = lk->lk_lock)
cpu_spinwait();
}
}
/*
* Try to set the LK_EXCLUSIVE_WAITERS flag. If we
* fail, loop back and retry.
*/
if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
if (!atomic_cmpset_ptr(&lk->lk_lock, x,
x | LK_EXCLUSIVE_WAITERS)) {
sleepq_release(&lk->lock_object);
continue;
}
LOCK_LOG2(lk, "%s: %p set drain waiters flag",
__func__, lk);
}
/*
* As far as we have been unable to acquire the
* exclusive lock and the exclusive waiters flag
* is set, we will sleep.
*/
if (flags & LK_INTERLOCK) {
class->lc_unlock(ilk);
flags &= ~LK_INTERLOCK;
}
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
GIANT_SAVE();
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK,
SQ_EXCLUSIVE_QUEUE);
sleepq_wait(&lk->lock_object, ipri & PRIMASK);
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
GIANT_RESTORE();
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
__func__, lk);
}
if (error == 0) {
lock_profile_obtain_lock_success(&lk->lock_object,
contested, waittime, file, line);
LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0,
lk->lk_recurse, file, line);
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
LK_TRYWIT(flags), file, line);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
TD_LOCKS_INC(curthread);
STACK_SAVE(lk);
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
break;
default:
if (flags & LK_INTERLOCK)
class->lc_unlock(ilk);
panic("%s: unknown lockmgr request 0x%x\n", __func__, op);
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (flags & LK_INTERLOCK)
class->lc_unlock(ilk);
If a thread that is swapped out is made runnable, then the setrunnable() routine wakes up proc0 so that proc0 can swap the thread back in. Historically, this has been done by waking up proc0 directly from setrunnable() itself via a wakeup(). When waking up a sleeping thread that was swapped out (the usual case when waking proc0 since only sleeping threads are eligible to be swapped out), this resulted in a bit of recursion (e.g. wakeup() -> setrunnable() -> wakeup()). With sleep queues having separate locks in 6.x and later, this caused a spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock). An attempt was made to fix this in 7.0 by making the proc0 wakeup use the ithread mechanism for doing the wakeup. However, this required grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated into the same LOR since the thread lock would be some other sleepq lock. Fix this by deferring the wakeup of the swapper until after the sleepq lock held by the upper layer has been locked. The setrunnable() routine now returns a boolean value to indicate whether or not proc0 needs to be woken up. The end result is that consumers of the sleepq API such as *sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup proc0 if they get a non-zero return value from sleepq_abort(), sleepq_broadcast(), or sleepq_signal(). Discussed with: jeff Glanced at by: sam Tested by: Jurgen Weber jurgen - ish com au MFC after: 2 weeks
2008-08-05 20:02:31 +00:00
if (wakeup_swapper)
kick_proc0();
Add WITNESS support to lockmgr locking primitive. This support tries to be as parallel as possible with other locking primitives, but there are differences; more specifically: - The base witness support is alredy equipped for allowing lock duplication acquisition as lockmgr rely on this. - In the case of lockmgr_disown() the lock result unlocked by witness even if it is still held by the "kernel context" - In the case of upgrading we can have 3 different situations: * Total unlocking of the shared lock and nothing else * Real witness upgrade if the owner is the first upgrader * Shared unlocking and exclusive locking if the owner is not the first upgrade but it is still allowed to upgrade - LK_DRAIN is basically handled like an exclusive acquisition Additively new options LK_NODUP and LK_NOWITNESS can now be used with lockinit(): LK_NOWITNESS disables WITNESS for the specified lock while LK_NODUP enable duplicated locks tracking. This will require manpages update and a __FreeBSD_version bumping (addressed by further commits). This patch also fixes a problem occurring if a lockmgr is held in exclusive mode and the same owner try to acquire it in shared mode: currently there is a spourious shared locking acquisition while what we really want is a lock downgrade. Probabilly, this situation can be better served with a EDEADLK failing errno return. Side note: first testing on this patch alredy reveleated several LORs reported, so please expect LORs cascades until resolved. NTFS also is reported broken by WITNESS introduction. BTW, NTFS is exposing a lock leak which needs to be fixed, and this patch can help it out if rightly tweaked. Tested by: kris, yar, Scot Hetzel <swhetzel at gmail dot com>
2008-02-06 00:37:14 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
return (error);
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
}
Convert lockmgr locks from using simple locks to using mutexes. Add lockdestroy() and appropriate invocations, which corresponds to lockinit() and must be called to clean up after a lockmgr lock is no longer needed.
2000-10-04 01:29:17 +00:00
void
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
_lockmgr_disown(struct lock *lk, const char *file, int line)
Convert lockmgr locks from using simple locks to using mutexes. Add lockdestroy() and appropriate invocations, which corresponds to lockinit() and must be called to clean up after a lockmgr lock is no longer needed.
2000-10-04 01:29:17 +00:00
{
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
uintptr_t tid, x;
panic: add a switch and infrastructure for stopping other CPUs in SMP case Historical behavior of letting other CPUs merily go on is a default for time being. The new behavior can be switched on via kern.stop_scheduler_on_panic tunable and sysctl. Stopping of the CPUs has (at least) the following benefits: - more of the system state at panic time is preserved intact - threads and interrupts do not interfere with dumping of the system state Only one thread runs uninterrupted after panic if stop_scheduler_on_panic is set. That thread might call code that is also used in normal context and that code might use locks to prevent concurrent execution of certain parts. Those locks might be held by the stopped threads and would never be released. To work around this issue, it was decided that instead of explicit checks for panic context, we would rather put those checks inside the locking primitives. This change has substantial portions written and re-written by attilio and kib at various times. Other changes are heavily based on the ideas and patches submitted by jhb and mdf. bde has provided many insights into the details and history of the current code. The new behavior may cause problems for systems that use a USB keyboard for interfacing with system console. This is because of some unusual locking patterns in the ukbd code which have to be used because on one hand ukbd is below syscons, but on the other hand it has to interface with other usb code that uses regular mutexes/Giant for its concurrency protection. Dumping to USB-connected disks may also be affected. PR: amd64/139614 (at least) In cooperation with: attilio, jhb, kib, mdf Discussed with: arch@, bde Tested by: Eugene Grosbein <eugen@grosbein.net>, gnn, Steven Hartland <killing@multiplay.co.uk>, glebius, Andrew Boyer <aboyer@averesystems.com> (various versions of the patch) MFC after: 3 months (or never)
2011-12-11 21:02:01 +00:00
if (SCHEDULER_STOPPED())
return;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
tid = (uintptr_t)curthread;
Check for lockmgr recursion in case of disown and downgrade and panic also in !debugging kernel rather than having "undefined" behaviour. Tested by: avg MFC after: 1 week
2012-12-05 15:11:01 +00:00
_lockmgr_assert(lk, KA_XLOCKED, file, line);
/*
* Panic if the lock is recursed.
*/
if (lockmgr_xlocked(lk) && lockmgr_recursed(lk))
panic("%s: disown a recursed lockmgr @ %s:%d\n",
__func__, file, line);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
s/alredy/already/ in the comments and the log message.
2008-07-25 11:22:25 +00:00
* If the owner is already LK_KERNPROC just skip the whole operation.
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
*/
if (LK_HOLDER(lk->lk_lock) != tid)
return;
- Call lock_profile_release when we're transitioning a lock to be owned by LK_KERNPROC. Discussed with: attilio
2009-03-14 11:43:02 +00:00
lock_profile_release_lock(&lk->lock_object);
Add lockmgr(9) probes to the lockstat DTrace provider. They follow the conventions set by rw and sx lock probes. There is an additional lockstat:::lockmgr-disown probe. Update lockstat(1) to report on contention and hold events for lockmgr locks. Document the new probes in dtrace_lockstat.4, and deduplicate some of the existing probe descriptions. Reviewed by: mjg MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21355
2019-08-21 23:43:58 +00:00
LOCKSTAT_RECORD1(lockmgr__disown, lk, LOCKSTAT_WRITER);
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
TD_LOCKS_DEC(curthread);
Save the sack when doing a lockmgr_disown() call. Requested by: kib MFC: 3 days
2009-11-06 22:33:03 +00:00
STACK_SAVE(lk);
Move lock_profile_object_{init,destroy}() into lock_{init,destroy}().
2007-05-18 15:04:59 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
/*
* In order to preserve waiters flags, just spin.
*/
for (;;) {
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
x &= LK_ALL_WAITERS;
Use a "rel" memory barrier for disowning the lock as it cames from an exclusive locking operation.
2008-04-13 01:21:56 +00:00
if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
LK_KERNPROC | x))
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
return;
cpu_spinwait();
}
Convert lockmgr locks from using simple locks to using mutexes. Add lockdestroy() and appropriate invocations, which corresponds to lockinit() and must be called to clean up after a lockmgr lock is no longer needed.
2000-10-04 01:29:17 +00:00
}
Remove explicit calling of lockmgr() with the NULL argument. Now, lockmgr() function can only be called passing curthread and the KASSERT() is upgraded according with this. In order to support on-the-fly owner switching, the new function lockmgr_disown() has been introduced and gets used in BUF_KERNPROC(). KPI, so, results changed and FreeBSD version will be bumped soon. Differently from previous code, we assume idle thread cannot try to acquire the lockmgr as it cannot sleep, so loose the relative check[1] in BUF_KERNPROC(). Tested by: kris [1] kib asked for a KASSERT in the lockmgr_disown() about this condition, but after thinking at it, as this is a well known general rule, I found it not really necessary.
2008-01-08 23:48:31 +00:00
void
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
lockmgr_printinfo(const struct lock *lk)
Remove explicit calling of lockmgr() with the NULL argument. Now, lockmgr() function can only be called passing curthread and the KASSERT() is upgraded according with this. In order to support on-the-fly owner switching, the new function lockmgr_disown() has been introduced and gets used in BUF_KERNPROC(). KPI, so, results changed and FreeBSD version will be bumped soon. Differently from previous code, we assume idle thread cannot try to acquire the lockmgr as it cannot sleep, so loose the relative check[1] in BUF_KERNPROC(). Tested by: kris [1] kib asked for a KASSERT in the lockmgr_disown() about this condition, but after thinking at it, as this is a well known general rule, I found it not really necessary.
2008-01-08 23:48:31 +00:00
{
struct thread *td;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
uintptr_t x;
if (lk->lk_lock == LK_UNLOCKED)
Tweak the output of VOP_PRINT/vn_printf() some. - Align the fifo output in fifo_print() with other vn_printf() output. - Remove the leading space from lockmgr_printinfo() so its output lines up in vn_printf(). - lockmgr_printinfo() now ends with a newline, so remove an extra newline from vn_printf().
2009-02-06 20:06:48 +00:00
printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
else if (lk->lk_lock & LK_SHARE)
Tweak the output of VOP_PRINT/vn_printf() some. - Align the fifo output in fifo_print() with other vn_printf() output. - Remove the leading space from lockmgr_printinfo() so its output lines up in vn_printf(). - lockmgr_printinfo() now ends with a newline, so remove an extra newline from vn_printf().
2009-02-06 20:06:48 +00:00
printf("lock type %s: SHARED (count %ju)\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name,
(uintmax_t)LK_SHARERS(lk->lk_lock));
else {
td = lockmgr_xholder(lk);
Do not try to dereference thread pointer when the value is not a pointer. Reported and tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week
2014-11-13 17:44:35 +00:00
if (td == (struct thread *)LK_KERNPROC)
printf("lock type %s: EXCL by KERNPROC\n",
lk->lock_object.lo_name);
else
printf("lock type %s: EXCL by thread %p "
"(pid %d, %s, tid %d)\n", lk->lock_object.lo_name,
td, td->td_proc->p_pid, td->td_proc->p_comm,
td->td_tid);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
}
Remove explicit calling of lockmgr() with the NULL argument. Now, lockmgr() function can only be called passing curthread and the KASSERT() is upgraded according with this. In order to support on-the-fly owner switching, the new function lockmgr_disown() has been introduced and gets used in BUF_KERNPROC(). KPI, so, results changed and FreeBSD version will be bumped soon. Differently from previous code, we assume idle thread cannot try to acquire the lockmgr as it cannot sleep, so loose the relative check[1] in BUF_KERNPROC(). Tested by: kris [1] kib asked for a KASSERT in the lockmgr_disown() about this condition, but after thinking at it, as this is a well known general rule, I found it not really necessary.
2008-01-08 23:48:31 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
x = lk->lk_lock;
if (x & LK_EXCLUSIVE_WAITERS)
printf(" with exclusive waiters pending\n");
if (x & LK_SHARED_WAITERS)
printf(" with shared waiters pending\n");
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
if (x & LK_EXCLUSIVE_SPINNERS)
printf(" with exclusive spinners pending\n");
Remove explicit calling of lockmgr() with the NULL argument. Now, lockmgr() function can only be called passing curthread and the KASSERT() is upgraded according with this. In order to support on-the-fly owner switching, the new function lockmgr_disown() has been introduced and gets used in BUF_KERNPROC(). KPI, so, results changed and FreeBSD version will be bumped soon. Differently from previous code, we assume idle thread cannot try to acquire the lockmgr as it cannot sleep, so loose the relative check[1] in BUF_KERNPROC(). Tested by: kris [1] kib asked for a KASSERT in the lockmgr_disown() about this condition, but after thinking at it, as this is a well known general rule, I found it not really necessary.
2008-01-08 23:48:31 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
STACK_PRINT(lk);
Remove explicit calling of lockmgr() with the NULL argument. Now, lockmgr() function can only be called passing curthread and the KASSERT() is upgraded according with this. In order to support on-the-fly owner switching, the new function lockmgr_disown() has been introduced and gets used in BUF_KERNPROC(). KPI, so, results changed and FreeBSD version will be bumped soon. Differently from previous code, we assume idle thread cannot try to acquire the lockmgr as it cannot sleep, so loose the relative check[1] in BUF_KERNPROC(). Tested by: kris [1] kib asked for a KASSERT in the lockmgr_disown() about this condition, but after thinking at it, as this is a well known general rule, I found it not really necessary.
2008-01-08 23:48:31 +00:00
}
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
int
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
lockstatus(const struct lock *lk)
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
{
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
uintptr_t v, x;
int ret;
Change the M_NAMEI allocations to use the zone allocator. This change plus the previous changes to use the zone allocator decrease the useage of malloc by half. The Zone allocator will be upgradeable to be able to use per CPU-pools, and has more intelligent usage of SPLs. Additionally, it has reasonable stats gathering capabilities, while making most calls inline.
1997-09-21 04:24:27 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
ret = LK_SHARED;
lockmgr: add a helper for reading the lock value
2020-07-21 14:39:20 +00:00
x = lockmgr_read_value(lk);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
v = LK_HOLDER(x);
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if ((x & LK_SHARE) == 0) {
if (v == (uintptr_t)curthread || v == LK_KERNPROC)
ret = LK_EXCLUSIVE;
else
ret = LK_EXCLOTHER;
} else if (x == LK_UNLOCKED)
ret = 0;
return (ret);
Import 4.4BSD-Lite2 onto CSRG branch
1997-03-25 16:27:20 +00:00
}
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
#ifdef INVARIANT_SUPPORT
Add some FEATURE macros for various features (AUDIT/CAM/IPC/KTR/MAC/NFS/NTP/ PMC/SYSV/...). No FreeBSD version bump, the userland application to query the features will be committed last and can serve as an indication of the availablility if needed. Sponsored by: Google Summer of Code 2010 Submitted by: kibab Reviewed by: arch@ (parts by rwatson, trasz, jhb) X-MFC after: to be determined in last commit with code from this project
2011-02-25 10:11:01 +00:00
FEATURE(invariant_support,
"Support for modules compiled with INVARIANTS option");
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
#ifndef INVARIANTS
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#undef _lockmgr_assert
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
#endif
void
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
_lockmgr_assert(const struct lock *lk, int what, const char *file, int line)
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
{
int slocked = 0;
Add KERNEL_PANICKED macro for use in place of direct panicstr tests
2020-01-12 06:07:54 +00:00
if (KERNEL_PANICKED())
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
return;
switch (what) {
case KA_SLOCKED:
case KA_SLOCKED | KA_NOTRECURSED:
case KA_SLOCKED | KA_RECURSED:
slocked = 1;
case KA_LOCKED:
case KA_LOCKED | KA_NOTRECURSED:
case KA_LOCKED | KA_RECURSED:
- Re-introduce WITNESS support for lockmgr. About the old implementation the only one difference is that lockmgr*() functions now accept LK_NOWITNESS flag which skips ordering for the instanced calling. - Remove an unuseful stub in witness_checkorder() (because the above check doesn't allow ever happening) and allow witness_upgrade() to accept non-try operation too.
2008-04-12 19:57:30 +00:00
#ifdef WITNESS
/*
* We cannot trust WITNESS if the lock is held in exclusive
* mode and a call to lockmgr_disown() happened.
* Workaround this skipping the check if the lock is held in
* exclusive mode even for the KA_LOCKED case.
*/
if (slocked || (lk->lk_lock & LK_SHARE)) {
witness_assert(&lk->lock_object, what, file, line);
break;
}
#endif
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (lk->lk_lock == LK_UNLOCKED ||
((lk->lk_lock & LK_SHARE) == 0 && (slocked ||
(!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)))))
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
panic("Lock %s not %slocked @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, slocked ? "share" : "",
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
file, line);
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if ((lk->lk_lock & LK_SHARE) == 0) {
if (lockmgr_recursed(lk)) {
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
if (what & KA_NOTRECURSED)
panic("Lock %s recursed @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, file,
line);
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
} else if (what & KA_RECURSED)
panic("Lock %s not recursed @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, file, line);
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
}
break;
case KA_XLOCKED:
case KA_XLOCKED | KA_NOTRECURSED:
case KA_XLOCKED | KA_RECURSED:
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
panic("Lock %s not exclusively locked @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, file, line);
if (lockmgr_recursed(lk)) {
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
if (what & KA_NOTRECURSED)
panic("Lock %s recursed @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, file, line);
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
} else if (what & KA_RECURSED)
panic("Lock %s not recursed @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, file, line);
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
break;
case KA_UNLOCKED:
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (lockmgr_xlocked(lk) || lockmgr_disowned(lk))
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
panic("Lock %s exclusively locked @ %s:%d\n",
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk->lock_object.lo_name, file, line);
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
break;
default:
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file,
line);
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
}
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
#endif
- Add real assertions to lockmgr locking primitives. A couple of notes for this: * WITNESS support, when enabled, is only used for shared locks in order to avoid problems with the "disowned" locks * KA_HELD and KA_UNHELD only exists in the lockmgr namespace in order to assert for a generic thread (not curthread) owning or not the lock. Really, this kind of check is bogus but it seems very widespread in the consumers code. So, for the moment, we cater this untrusted behaviour, until the consumers are not fixed and the options could be removed (hopefully during 8.0-CURRENT lifecycle) * Implementing KA_HELD and KA_UNHELD (not surported natively by WITNESS) made necessary the introduction of LA_MASKASSERT which specifies the range for default lock assertion flags * About other aspects, lockmgr_assert() follows exactly what other locking primitives offer about this operation. - Build real assertions for buffer cache locks on the top of lockmgr_assert(). They can be used with the BUF_ASSERT_*(bp) paradigm. - Add checks at lock destruction time and use a cookie for verifying lock integrity at any operation. - Redefine BUF_LOCKFREE() in order to not use a direct assert but let it rely on the aforementioned destruction time check. KPI results evidently broken, so __FreeBSD_version bumping and manpage update result necessary and will be committed soon. Side note: lockmgr_assert() will be used soon in order to implement real assertions in the vnode namespace replacing the legacy and still bogus "VOP_ISLOCKED()" way. Tested by: kris (earlier version) Reviewed by: jhb
2008-02-13 20:44:19 +00:00
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
#ifdef DDB
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
int
lockmgr_chain(struct thread *td, struct thread **ownerp)
{
sleep(9), sleepqueue(9): const'ify wchan pointers _sleep(9), wakeup(9), sleepqueue(9), et al do not dereference or modify the channel pointers provided in any way; they are merely used as intptrs into a dictionary structure to match waiters with wakers. Correctly annotate this such that _sleep() and wakeup() may be used on const pointers without invoking ugly patterns like __DECONST(). Plumb const through all of the underlying sleepqueue bits. No functional change. Reviewed by: rlibby Discussed with: kib, markj Differential Revision: https://reviews.freebsd.org/D22914
2019-12-24 16:19:33 +00:00
const struct lock *lk;
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
lk = td->td_wchan;
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr)
return (0);
db_printf("blocked on lockmgr %s", lk->lock_object.lo_name);
if (lk->lk_lock & LK_SHARE)
db_printf("SHARED (count %ju)\n",
(uintmax_t)LK_SHARERS(lk->lk_lock));
else
db_printf("EXCL\n");
*ownerp = lockmgr_xholder(lk);
Handle the case when a thread is blocked on a lockmgr lock with LK_DRAIN in DDB's 'show sleepchain'. MFC after: 3 days
2007-03-21 19:28:20 +00:00
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
return (1);
}
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
static void
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
db_show_lockmgr(const struct lock_object *lock)
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
{
struct thread *td;
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
const struct lock *lk;
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
Constify arguments for locking KPIs where possible. This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
2011-11-16 21:51:17 +00:00
lk = (const struct lock *)lock;
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
- Use lock_init/lock_destroy() to setup the lock_object inside of lockmgr. We can now use LOCK_CLASS() as a stronger check in lockmgr_chain() as a result. This required putting back lk_flags as lockmgr's use of flags conflicted with other flags in lo_flags otherwise. - Tweak 'show lock' output for lockmgr to match sx, rw, and mtx.
2007-03-30 18:07:24 +00:00
db_printf(" state: ");
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
if (lk->lk_lock == LK_UNLOCKED)
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
db_printf("UNLOCKED\n");
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
else if (lk->lk_lock & LK_SHARE)
db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock));
else {
td = lockmgr_xholder(lk);
if (td == (struct thread *)LK_KERNPROC)
db_printf("XLOCK: LK_KERNPROC\n");
else
db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
td->td_tid, td->td_proc->p_pid,
td->td_proc->p_comm);
if (lockmgr_recursed(lk))
db_printf(" recursed: %d\n", lk->lk_recurse);
}
db_printf(" waiters: ");
switch (lk->lk_lock & LK_ALL_WAITERS) {
case LK_SHARED_WAITERS:
db_printf("shared\n");
Add missing 'break' statement. Found with: Coverity Prevent(tm) CID: 3919
2009-05-12 17:05:40 +00:00
break;
Optimize lockmgr in order to get rid of the pool mutex interlock, of the state transitioning flags and of msleep(9) callings. Use, instead, an algorithm very similar to what sx(9) and rwlock(9) alredy do and direct accesses to the sleepqueue(9) primitive. In order to avoid writer starvation a mechanism very similar to what rwlock(9) uses now is implemented, with the correspective per-thread shared lockmgrs counter. This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and lockmgr_args_rw(). These two are like the 2 "normal" versions, but they both accept a rwlock as interlock. In order to realize this, the general lockmgr manager function "__lockmgr_args()" has been implemented through the generic lock layer. It supports all the blocking primitives, but currently only these 2 mappers live. The patch drops the support for WITNESS atm, but it will be probabilly added soon. Also, there is a little race in the draining code which is also present in the current CVS stock implementation: if some sharers, once they wakeup, are in the runqueue they can contend the lock with the exclusive drainer. This is hard to be fixed but the now committed code mitigate this issue a lot better than the (past) CVS version. In addition assertive KA_HELD and KA_UNHELD have been made mute assertions because they are dangerous and they will be nomore supported soon. In order to avoid namespace pollution, stack.h is splitted into two parts: one which includes only the "struct stack" definition (_stack.h) and one defining the KPI. In this way, newly added _lockmgr.h can just include _stack.h. Kernel ABI results heavilly changed by this commit (the now committed version of "struct lock" is a lot smaller than the previous one) and KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction, so manpages and __FreeBSD_version will be updated accordingly. Tested by: kris, pho, jeff, danger Reviewed by: jeff Sponsored by: Google, Summer of Code program 2007
2008-04-06 20:08:51 +00:00
case LK_EXCLUSIVE_WAITERS:
db_printf("exclusive\n");
break;
case LK_ALL_WAITERS:
db_printf("shared and exclusive\n");
break;
default:
db_printf("none\n");
}
Introduce support for adaptive spinning in lockmgr. Actually, as it did receive few tuning, the support is disabled by default, but it can opt-in with the option ADAPTIVE_LOCKMGRS. Due to the nature of lockmgrs, adaptive spinning needs to be selectively enabled for any interested lockmgr. The support is bi-directional, or, in other ways, it will work in both cases if the lock is held in read or write way. In particular, the read path is passible of further tunning using the sysctls debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls should be axed or compiled out before release. Addictionally note that adaptive spinning doesn't cope well with LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers of LK_SLEEPFAIL are mainly interested in knowing if the interlock was dropped or not in order to reacquire it and re-test initial conditions. This directly interacts with adaptive spinning because lockmgr needs to drop the interlock while spinning in order to avoid a deadlock (further details in the comments inside the patch). Final note: finding someone willing to help on tuning this with relevant workloads would be either very important and appreciated. Tested by: jeff, pho Requested by: many
2009-06-17 01:55:42 +00:00
db_printf(" spinners: ");
if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS)
db_printf("exclusive\n");
else
db_printf("none\n");
Add a 'show lockmgr' command that dumps the relevant details of a lockmgr lock.
2006-08-15 16:42:16 +00:00
}
#endif
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