freebsd-skq/sys/vm/vm_pageout.c

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/*-
* Copyright (c) 1991 Regents of the University of California.
* All rights reserved.
* Copyright (c) 1994 John S. Dyson
* All rights reserved.
* Copyright (c) 1994 David Greenman
* All rights reserved.
* Copyright (c) 2005 Yahoo! Technologies Norway AS
* All rights reserved.
1994-05-24 10:09:53 +00:00
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* 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
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
1994-05-24 10:09:53 +00:00
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
1994-08-02 07:55:43 +00:00
* from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
1994-05-24 10:09:53 +00:00
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
*
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* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
1994-05-24 10:09:53 +00:00
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
*
1994-05-24 10:09:53 +00:00
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* The proverbial page-out daemon.
*/
2003-06-11 23:50:51 +00:00
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_vm.h"
#include "opt_kdtrace.h"
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#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/kthread.h>
#include <sys/ktr.h>
#include <sys/mount.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sdt.h>
1995-02-14 06:14:28 +00:00
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/rwlock.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
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#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
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#include <vm/vm_page.h>
#include <vm/vm_map.h>
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#include <vm/vm_pageout.h>
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
#include <vm/vm_pager.h>
#include <vm/vm_phys.h>
#include <vm/swap_pager.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
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/*
* System initialization
*/
/* the kernel process "vm_pageout"*/
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static void vm_pageout(void);
static void vm_pageout_init(void);
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static int vm_pageout_clean(vm_page_t);
static void vm_pageout_scan(struct vm_domain *vmd, int pass);
static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass);
SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init,
NULL);
struct proc *pageproc;
static struct kproc_desc page_kp = {
"pagedaemon",
vm_pageout,
&pageproc
};
SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start,
&page_kp);
SDT_PROVIDER_DEFINE(vm);
SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache);
SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan);
#if !defined(NO_SWAPPING)
/* the kernel process "vm_daemon"*/
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static void vm_daemon(void);
static struct proc *vmproc;
static struct kproc_desc vm_kp = {
"vmdaemon",
vm_daemon,
&vmproc
};
SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
#endif
int vm_pages_needed; /* Event on which pageout daemon sleeps */
int vm_pageout_deficit; /* Estimated number of pages deficit */
int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
int vm_pageout_wakeup_thresh;
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#if !defined(NO_SWAPPING)
static int vm_pageout_req_swapout; /* XXX */
static int vm_daemon_needed;
static struct mtx vm_daemon_mtx;
/* Allow for use by vm_pageout before vm_daemon is initialized. */
MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
#endif
static int vm_max_launder = 32;
static int vm_pageout_update_period;
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static int defer_swap_pageouts;
static int disable_swap_pageouts;
static int lowmem_period = 10;
static int lowmem_ticks;
#if defined(NO_SWAPPING)
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static int vm_swap_enabled = 0;
static int vm_swap_idle_enabled = 0;
#else
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static int vm_swap_enabled = 1;
static int vm_swap_idle_enabled = 0;
#endif
SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh,
CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0,
"free page threshold for waking up the pageout daemon");
SYSCTL_INT(_vm, OID_AUTO, max_launder,
CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
SYSCTL_INT(_vm, OID_AUTO, pageout_update_period,
CTLFLAG_RW, &vm_pageout_update_period, 0,
"Maximum active LRU update period");
SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0,
"Low memory callback period");
#if defined(NO_SWAPPING)
SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout");
SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
#else
SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
#endif
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SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
static int pageout_lock_miss;
SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
#define VM_PAGEOUT_PAGE_COUNT 16
int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
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int vm_page_max_wired; /* XXX max # of wired pages system-wide */
SYSCTL_INT(_vm, OID_AUTO, max_wired,
CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
1994-05-24 10:09:53 +00:00
static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *);
static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t,
vm_paddr_t);
#if !defined(NO_SWAPPING)
static void vm_pageout_map_deactivate_pages(vm_map_t, long);
static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long);
static void vm_req_vmdaemon(int req);
#endif
static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *);
/*
* Initialize a dummy page for marking the caller's place in the specified
* paging queue. In principle, this function only needs to set the flag
* PG_MARKER. Nonetheless, it wirte busies and initializes the hold count
* to one as safety precautions.
*/
static void
vm_pageout_init_marker(vm_page_t marker, u_short queue)
{
bzero(marker, sizeof(*marker));
marker->flags = PG_MARKER;
marker->busy_lock = VPB_SINGLE_EXCLUSIVER;
marker->queue = queue;
marker->hold_count = 1;
}
/*
* vm_pageout_fallback_object_lock:
*
* Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is
* known to have failed and page queue must be either PQ_ACTIVE or
* PQ_INACTIVE. To avoid lock order violation, unlock the page queues
* while locking the vm object. Use marker page to detect page queue
* changes and maintain notion of next page on page queue. Return
* TRUE if no changes were detected, FALSE otherwise. vm object is
* locked on return.
*
* This function depends on both the lock portion of struct vm_object
* and normal struct vm_page being type stable.
*/
static boolean_t
vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
{
struct vm_page marker;
struct vm_pagequeue *pq;
boolean_t unchanged;
u_short queue;
vm_object_t object;
queue = m->queue;
vm_pageout_init_marker(&marker, queue);
pq = vm_page_pagequeue(m);
object = m->object;
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
vm_pagequeue_unlock(pq);
vm_page_unlock(m);
VM_OBJECT_WLOCK(object);
vm_page_lock(m);
vm_pagequeue_lock(pq);
/* Page queue might have changed. */
*next = TAILQ_NEXT(&marker, plinks.q);
unchanged = (m->queue == queue &&
m->object == object &&
&marker == TAILQ_NEXT(m, plinks.q));
TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
return (unchanged);
}
/*
* Lock the page while holding the page queue lock. Use marker page
* to detect page queue changes and maintain notion of next page on
* page queue. Return TRUE if no changes were detected, FALSE
* otherwise. The page is locked on return. The page queue lock might
* be dropped and reacquired.
*
* This function depends on normal struct vm_page being type stable.
*/
static boolean_t
vm_pageout_page_lock(vm_page_t m, vm_page_t *next)
{
struct vm_page marker;
struct vm_pagequeue *pq;
boolean_t unchanged;
u_short queue;
vm_page_lock_assert(m, MA_NOTOWNED);
if (vm_page_trylock(m))
return (TRUE);
queue = m->queue;
vm_pageout_init_marker(&marker, queue);
pq = vm_page_pagequeue(m);
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
vm_pagequeue_unlock(pq);
vm_page_lock(m);
vm_pagequeue_lock(pq);
/* Page queue might have changed. */
*next = TAILQ_NEXT(&marker, plinks.q);
unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q));
TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
return (unchanged);
}
1994-05-24 10:09:53 +00:00
/*
* vm_pageout_clean:
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
*
* Clean the page and remove it from the laundry.
*
* We set the busy bit to cause potential page faults on this page to
* block. Note the careful timing, however, the busy bit isn't set till
* late and we cannot do anything that will mess with the page.
1994-05-24 10:09:53 +00:00
*/
static int
vm_pageout_clean(vm_page_t m)
1994-05-24 10:09:53 +00:00
{
2001-07-04 19:00:13 +00:00
vm_object_t object;
vm_page_t mc[2*vm_pageout_page_count], pb, ps;
int pageout_count;
int ib, is, page_base;
vm_pindex_t pindex = m->pindex;
vm_page_lock_assert(m, MA_OWNED);
object = m->object;
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
* with the new swapper, but we could have serious problems paging
* out other object types if there is insufficient memory.
*
* Unfortunately, checking free memory here is far too late, so the
* check has been moved up a procedural level.
*/
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
/*
* Can't clean the page if it's busy or held.
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
*/
vm_page_assert_unbusied(m);
KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m));
vm_page_unlock(m);
1994-05-24 10:09:53 +00:00
mc[vm_pageout_page_count] = pb = ps = m;
pageout_count = 1;
page_base = vm_pageout_page_count;
ib = 1;
is = 1;
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
/*
* Scan object for clusterable pages.
*
* We can cluster ONLY if: ->> the page is NOT
* clean, wired, busy, held, or mapped into a
* buffer, and one of the following:
* 1) The page is inactive, or a seldom used
* active page.
* -or-
* 2) we force the issue.
*
* During heavy mmap/modification loads the pageout
* daemon can really fragment the underlying file
* due to flushing pages out of order and not trying
* align the clusters (which leave sporatic out-of-order
* holes). To solve this problem we do the reverse scan
* first and attempt to align our cluster, then do a
* forward scan if room remains.
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
*/
more:
while (ib && pageout_count < vm_pageout_page_count) {
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
vm_page_t p;
if (ib > pindex) {
ib = 0;
break;
}
if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) {
ib = 0;
break;
}
vm_page_lock(p);
vm_page_test_dirty(p);
if (p->dirty == 0 ||
p->queue != PQ_INACTIVE ||
p->hold_count != 0) { /* may be undergoing I/O */
vm_page_unlock(p);
ib = 0;
break;
}
vm_page_unlock(p);
mc[--page_base] = pb = p;
++pageout_count;
++ib;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
/*
* alignment boundry, stop here and switch directions. Do
* not clear ib.
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
*/
if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
break;
}
while (pageout_count < vm_pageout_page_count &&
pindex + is < object->size) {
vm_page_t p;
if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p))
break;
vm_page_lock(p);
vm_page_test_dirty(p);
if (p->dirty == 0 ||
p->queue != PQ_INACTIVE ||
p->hold_count != 0) { /* may be undergoing I/O */
vm_page_unlock(p);
break;
}
vm_page_unlock(p);
mc[page_base + pageout_count] = ps = p;
++pageout_count;
++is;
1994-05-24 10:09:53 +00:00
}
/*
* If we exhausted our forward scan, continue with the reverse scan
* when possible, even past a page boundry. This catches boundry
* conditions.
*/
if (ib && pageout_count < vm_pageout_page_count)
goto more;
/*
* we allow reads during pageouts...
*/
return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL,
NULL));
}
/*
* vm_pageout_flush() - launder the given pages
*
* The given pages are laundered. Note that we setup for the start of
* I/O ( i.e. busy the page ), mark it read-only, and bump the object
* reference count all in here rather then in the parent. If we want
* the parent to do more sophisticated things we may have to change
* the ordering.
*
* Returned runlen is the count of pages between mreq and first
* page after mreq with status VM_PAGER_AGAIN.
* *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL
* for any page in runlen set.
*/
int
vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen,
boolean_t *eio)
{
vm_object_t object = mc[0]->object;
int pageout_status[count];
int numpagedout = 0;
int i, runlen;
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* Initiate I/O. Bump the vm_page_t->busy counter and
* mark the pages read-only.
*
* We do not have to fixup the clean/dirty bits here... we can
* allow the pager to do it after the I/O completes.
*
* NOTE! mc[i]->dirty may be partial or fragmented due to an
* edge case with file fragments.
*/
This mega-commit is meant to fix numerous interrelated problems. There has been some bitrot and incorrect assumptions in the vfs_bio code. These problems have manifest themselves worse on NFS type filesystems, but can still affect local filesystems under certain circumstances. Most of the problems have involved mmap consistancy, and as a side-effect broke the vfs.ioopt code. This code might have been committed seperately, but almost everything is interrelated. 1) Allow (pmap_object_init_pt) prefaulting of buffer-busy pages that are fully valid. 2) Rather than deactivating erroneously read initial (header) pages in kern_exec, we now free them. 3) Fix the rundown of non-VMIO buffers that are in an inconsistent (missing vp) state. 4) Fix the disassociation of pages from buffers in brelse. The previous code had rotted and was faulty in a couple of important circumstances. 5) Remove a gratuitious buffer wakeup in vfs_vmio_release. 6) Remove a crufty and currently unused cluster mechanism for VBLK files in vfs_bio_awrite. When the code is functional, I'll add back a cleaner version. 7) The page busy count wakeups assocated with the buffer cache usage were incorrectly cleaned up in a previous commit by me. Revert to the original, correct version, but with a cleaner implementation. 8) The cluster read code now tries to keep data associated with buffers more aggressively (without breaking the heuristics) when it is presumed that the read data (buffers) will be soon needed. 9) Change to filesystem lockmgr locks so that they use LK_NOPAUSE. The delay loop waiting is not useful for filesystem locks, due to the length of the time intervals. 10) Correct and clean-up spec_getpages. 11) Implement a fully functional nfs_getpages, nfs_putpages. 12) Fix nfs_write so that modifications are coherent with the NFS data on the server disk (at least as well as NFS seems to allow.) 13) Properly support MS_INVALIDATE on NFS. 14) Properly pass down MS_INVALIDATE to lower levels of the VM code from vm_map_clean. 15) Better support the notion of pages being busy but valid, so that fewer in-transit waits occur. (use p->busy more for pageouts instead of PG_BUSY.) Since the page is fully valid, it is still usable for reads. 16) It is possible (in error) for cached pages to be busy. Make the page allocation code handle that case correctly. (It should probably be a printf or panic, but I want the system to handle coding errors robustly. I'll probably add a printf.) 17) Correct the design and usage of vm_page_sleep. It didn't handle consistancy problems very well, so make the design a little less lofty. After vm_page_sleep, if it ever blocked, it is still important to relookup the page (if the object generation count changed), and verify it's status (always.) 18) In vm_pageout.c, vm_pageout_clean had rotted, so clean that up. 19) Push the page busy for writes and VM_PROT_READ into vm_pageout_flush. 20) Fix vm_pager_put_pages and it's descendents to support an int flag instead of a boolean, so that we can pass down the invalidate bit.
1998-03-07 21:37:31 +00:00
for (i = 0; i < count; i++) {
KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL,
("vm_pageout_flush: partially invalid page %p index %d/%d",
mc[i], i, count));
vm_page_sbusy(mc[i]);
pmap_remove_write(mc[i]);
This mega-commit is meant to fix numerous interrelated problems. There has been some bitrot and incorrect assumptions in the vfs_bio code. These problems have manifest themselves worse on NFS type filesystems, but can still affect local filesystems under certain circumstances. Most of the problems have involved mmap consistancy, and as a side-effect broke the vfs.ioopt code. This code might have been committed seperately, but almost everything is interrelated. 1) Allow (pmap_object_init_pt) prefaulting of buffer-busy pages that are fully valid. 2) Rather than deactivating erroneously read initial (header) pages in kern_exec, we now free them. 3) Fix the rundown of non-VMIO buffers that are in an inconsistent (missing vp) state. 4) Fix the disassociation of pages from buffers in brelse. The previous code had rotted and was faulty in a couple of important circumstances. 5) Remove a gratuitious buffer wakeup in vfs_vmio_release. 6) Remove a crufty and currently unused cluster mechanism for VBLK files in vfs_bio_awrite. When the code is functional, I'll add back a cleaner version. 7) The page busy count wakeups assocated with the buffer cache usage were incorrectly cleaned up in a previous commit by me. Revert to the original, correct version, but with a cleaner implementation. 8) The cluster read code now tries to keep data associated with buffers more aggressively (without breaking the heuristics) when it is presumed that the read data (buffers) will be soon needed. 9) Change to filesystem lockmgr locks so that they use LK_NOPAUSE. The delay loop waiting is not useful for filesystem locks, due to the length of the time intervals. 10) Correct and clean-up spec_getpages. 11) Implement a fully functional nfs_getpages, nfs_putpages. 12) Fix nfs_write so that modifications are coherent with the NFS data on the server disk (at least as well as NFS seems to allow.) 13) Properly support MS_INVALIDATE on NFS. 14) Properly pass down MS_INVALIDATE to lower levels of the VM code from vm_map_clean. 15) Better support the notion of pages being busy but valid, so that fewer in-transit waits occur. (use p->busy more for pageouts instead of PG_BUSY.) Since the page is fully valid, it is still usable for reads. 16) It is possible (in error) for cached pages to be busy. Make the page allocation code handle that case correctly. (It should probably be a printf or panic, but I want the system to handle coding errors robustly. I'll probably add a printf.) 17) Correct the design and usage of vm_page_sleep. It didn't handle consistancy problems very well, so make the design a little less lofty. After vm_page_sleep, if it ever blocked, it is still important to relookup the page (if the object generation count changed), and verify it's status (always.) 18) In vm_pageout.c, vm_pageout_clean had rotted, so clean that up. 19) Push the page busy for writes and VM_PROT_READ into vm_pageout_flush. 20) Fix vm_pager_put_pages and it's descendents to support an int flag instead of a boolean, so that we can pass down the invalidate bit.
1998-03-07 21:37:31 +00:00
}
vm_object_pip_add(object, count);
vm_pager_put_pages(object, mc, count, flags, pageout_status);
1994-05-24 10:09:53 +00:00
runlen = count - mreq;
if (eio != NULL)
*eio = FALSE;
for (i = 0; i < count; i++) {
vm_page_t mt = mc[i];
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
KASSERT(pageout_status[i] == VM_PAGER_PEND ||
!pmap_page_is_write_mapped(mt),
("vm_pageout_flush: page %p is not write protected", mt));
switch (pageout_status[i]) {
case VM_PAGER_OK:
case VM_PAGER_PEND:
numpagedout++;
break;
case VM_PAGER_BAD:
/*
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
* Page outside of range of object. Right now we
* essentially lose the changes by pretending it
* worked.
*/
vm_page_undirty(mt);
break;
case VM_PAGER_ERROR:
case VM_PAGER_FAIL:
/*
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
* If page couldn't be paged out, then reactivate the
* page so it doesn't clog the inactive list. (We
* will try paging out it again later).
*/
vm_page_lock(mt);
vm_page_activate(mt);
vm_page_unlock(mt);
if (eio != NULL && i >= mreq && i - mreq < runlen)
*eio = TRUE;
break;
case VM_PAGER_AGAIN:
if (i >= mreq && i - mreq < runlen)
runlen = i - mreq;
1994-05-24 10:09:53 +00:00
break;
}
1994-05-24 10:09:53 +00:00
/*
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
* If the operation is still going, leave the page busy to
* block all other accesses. Also, leave the paging in
* progress indicator set so that we don't attempt an object
* collapse.
1994-05-24 10:09:53 +00:00
*/
if (pageout_status[i] != VM_PAGER_PEND) {
vm_object_pip_wakeup(object);
vm_page_sunbusy(mt);
if (vm_page_count_severe()) {
vm_page_lock(mt);
vm_page_try_to_cache(mt);
vm_page_unlock(mt);
}
1994-05-24 10:09:53 +00:00
}
}
if (prunlen != NULL)
*prunlen = runlen;
return (numpagedout);
}
1994-05-24 10:09:53 +00:00
static boolean_t
vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low,
vm_paddr_t high)
{
struct mount *mp;
struct vnode *vp;
vm_object_t object;
vm_paddr_t pa;
vm_page_t m, m_tmp, next;
int lockmode;
vm_pagequeue_lock(pq);
TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) {
if ((m->flags & PG_MARKER) != 0)
continue;
pa = VM_PAGE_TO_PHYS(m);
if (pa < low || pa + PAGE_SIZE > high)
continue;
if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) {
vm_page_unlock(m);
continue;
}
object = m->object;
if ((!VM_OBJECT_TRYWLOCK(object) &&
(!vm_pageout_fallback_object_lock(m, &next) ||
m->hold_count != 0)) || vm_page_busied(m)) {
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
continue;
}
vm_page_test_dirty(m);
if (m->dirty == 0 && object->ref_count != 0)
pmap_remove_all(m);
if (m->dirty != 0) {
vm_page_unlock(m);
if (tries == 0 || (object->flags & OBJ_DEAD) != 0) {
VM_OBJECT_WUNLOCK(object);
continue;
}
if (object->type == OBJT_VNODE) {
vm_pagequeue_unlock(pq);
vp = object->handle;
vm_object_reference_locked(object);
VM_OBJECT_WUNLOCK(object);
(void)vn_start_write(vp, &mp, V_WAIT);
lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
LK_SHARED : LK_EXCLUSIVE;
vn_lock(vp, lockmode | LK_RETRY);
VM_OBJECT_WLOCK(object);
vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
VM_OBJECT_WUNLOCK(object);
VOP_UNLOCK(vp, 0);
vm_object_deallocate(object);
vn_finished_write(mp);
return (TRUE);
} else if (object->type == OBJT_SWAP ||
object->type == OBJT_DEFAULT) {
vm_pagequeue_unlock(pq);
m_tmp = m;
vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC,
0, NULL, NULL);
VM_OBJECT_WUNLOCK(object);
return (TRUE);
}
} else {
/*
* Dequeue here to prevent lock recursion in
* vm_page_cache().
*/
vm_page_dequeue_locked(m);
vm_page_cache(m);
vm_page_unlock(m);
}
VM_OBJECT_WUNLOCK(object);
}
vm_pagequeue_unlock(pq);
return (FALSE);
}
/*
* Increase the number of cached pages. The specified value, "tries",
* determines which categories of pages are cached:
*
* 0: All clean, inactive pages within the specified physical address range
* are cached. Will not sleep.
* 1: The vm_lowmem handlers are called. All inactive pages within
* the specified physical address range are cached. May sleep.
* 2: The vm_lowmem handlers are called. All inactive and active pages
* within the specified physical address range are cached. May sleep.
*/
void
vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high)
{
int actl, actmax, inactl, inactmax, dom, initial_dom;
static int start_dom = 0;
if (tries > 0) {
/*
* Decrease registered cache sizes. The vm_lowmem handlers
* may acquire locks and/or sleep, so they can only be invoked
* when "tries" is greater than zero.
*/
SDT_PROBE0(vm, , , vm__lowmem_cache);
EVENTHANDLER_INVOKE(vm_lowmem, 0);
/*
* We do this explicitly after the caches have been drained
* above.
*/
uma_reclaim();
}
/*
* Make the next scan start on the next domain.
*/
initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains;
inactl = 0;
inactmax = vm_cnt.v_inactive_count;
actl = 0;
actmax = tries < 2 ? 0 : vm_cnt.v_active_count;
dom = initial_dom;
/*
* Scan domains in round-robin order, first inactive queues,
* then active. Since domain usually owns large physically
* contiguous chunk of memory, it makes sense to completely
* exhaust one domain before switching to next, while growing
* the pool of contiguous physical pages.
*
* Do not even start launder a domain which cannot contain
* the specified address range, as indicated by segments
* constituting the domain.
*/
again:
if (inactl < inactmax) {
if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
low, high) &&
vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE],
tries, low, high)) {
inactl++;
goto again;
}
if (++dom == vm_ndomains)
dom = 0;
if (dom != initial_dom)
goto again;
}
if (actl < actmax) {
if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
low, high) &&
vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE],
tries, low, high)) {
actl++;
goto again;
}
if (++dom == vm_ndomains)
dom = 0;
if (dom != initial_dom)
goto again;
}
}
#if !defined(NO_SWAPPING)
/*
* vm_pageout_object_deactivate_pages
*
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
* Deactivate enough pages to satisfy the inactive target
* requirements.
*
* The object and map must be locked.
*/
static void
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
long desired)
{
vm_object_t backing_object, object;
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
vm_page_t p;
int act_delta, remove_mode;
VM_OBJECT_ASSERT_LOCKED(first_object);
if ((first_object->flags & OBJ_FICTITIOUS) != 0)
return;
for (object = first_object;; object = backing_object) {
if (pmap_resident_count(pmap) <= desired)
goto unlock_return;
VM_OBJECT_ASSERT_LOCKED(object);
if ((object->flags & OBJ_UNMANAGED) != 0 ||
object->paging_in_progress != 0)
goto unlock_return;
remove_mode = 0;
if (object->shadow_count > 1)
remove_mode = 1;
/*
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
* Scan the object's entire memory queue.
*/
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
TAILQ_FOREACH(p, &object->memq, listq) {
if (pmap_resident_count(pmap) <= desired)
goto unlock_return;
if (vm_page_busied(p))
continue;
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
PCPU_INC(cnt.v_pdpages);
vm_page_lock(p);
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
if (p->wire_count != 0 || p->hold_count != 0 ||
!pmap_page_exists_quick(pmap, p)) {
vm_page_unlock(p);
continue;
}
act_delta = pmap_ts_referenced(p);
if ((p->aflags & PGA_REFERENCED) != 0) {
if (act_delta == 0)
act_delta = 1;
vm_page_aflag_clear(p, PGA_REFERENCED);
1994-05-24 10:09:53 +00:00
}
if (p->queue != PQ_ACTIVE && act_delta != 0) {
vm_page_activate(p);
p->act_count += act_delta;
} else if (p->queue == PQ_ACTIVE) {
if (act_delta == 0) {
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
p->act_count -= min(p->act_count,
ACT_DECLINE);
if (!remove_mode && p->act_count == 0) {
pmap_remove_all(p);
vm_page_deactivate(p);
} else
vm_page_requeue(p);
} else {
vm_page_activate(p);
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
if (p->act_count < ACT_MAX -
ACT_ADVANCE)
p->act_count += ACT_ADVANCE;
vm_page_requeue(p);
}
Reduce the scope of the page queues lock and the number of PG_REFERENCED changes in vm_pageout_object_deactivate_pages(). Simplify this function's inner loop using TAILQ_FOREACH(), and shorten some of its overly long lines. Update a stale comment. Assert that PG_REFERENCED may be cleared only if the object containing the page is locked. Add a comment documenting this. Assert that a caller to vm_page_requeue() holds the page queues lock, and assert that the page is on a page queue. Push down the page queues lock into pmap_ts_referenced() and pmap_page_exists_quick(). (As of now, there are no longer any pmap functions that expect to be called with the page queues lock held.) Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever be passed an unmanaged page. Assert this rather than returning "0" and "FALSE" respectively. ARM: Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH(). Push down the page queues lock inside of pmap_clearbit(), simplifying pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write(). Additionally, this allows for avoiding the acquisition of the page queues lock in some cases. PowerPC/AIM: moea*_page_exits_quick() and moea*_page_wired_mappings() will never be called before pmap initialization is complete. Therefore, the check for moea_initialized can be eliminated. Push down the page queues lock inside of moea*_clear_bit(), simplifying moea*_clear_modify() and moea*_clear_reference(). The last parameter to moea*_clear_bit() is never used. Eliminate it. PowerPC/BookE: Simplify mmu_booke_page_exists_quick()'s control flow. Reviewed by: kib@
2010-06-10 16:56:35 +00:00
} else if (p->queue == PQ_INACTIVE)
pmap_remove_all(p);
vm_page_unlock(p);
1994-05-24 10:09:53 +00:00
}
if ((backing_object = object->backing_object) == NULL)
goto unlock_return;
VM_OBJECT_RLOCK(backing_object);
if (object != first_object)
VM_OBJECT_RUNLOCK(object);
}
unlock_return:
if (object != first_object)
VM_OBJECT_RUNLOCK(object);
}
/*
* deactivate some number of pages in a map, try to do it fairly, but
* that is really hard to do.
*/
static void
vm_pageout_map_deactivate_pages(map, desired)
vm_map_t map;
long desired;
{
vm_map_entry_t tmpe;
vm_object_t obj, bigobj;
int nothingwired;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
if (!vm_map_trylock(map))
return;
bigobj = NULL;
nothingwired = TRUE;
/*
* first, search out the biggest object, and try to free pages from
* that.
*/
tmpe = map->header.next;
while (tmpe != &map->header) {
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
obj = tmpe->object.vm_object;
if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
if (obj->shadow_count <= 1 &&
(bigobj == NULL ||
bigobj->resident_page_count < obj->resident_page_count)) {
if (bigobj != NULL)
VM_OBJECT_RUNLOCK(bigobj);
bigobj = obj;
} else
VM_OBJECT_RUNLOCK(obj);
}
}
if (tmpe->wired_count > 0)
nothingwired = FALSE;
tmpe = tmpe->next;
}
if (bigobj != NULL) {
vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
VM_OBJECT_RUNLOCK(bigobj);
}
/*
* Next, hunt around for other pages to deactivate. We actually
* do this search sort of wrong -- .text first is not the best idea.
*/
tmpe = map->header.next;
while (tmpe != &map->header) {
if (pmap_resident_count(vm_map_pmap(map)) <= desired)
break;
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
obj = tmpe->object.vm_object;
if (obj != NULL) {
VM_OBJECT_RLOCK(obj);
vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
VM_OBJECT_RUNLOCK(obj);
}
}
tmpe = tmpe->next;
}
/*
* Remove all mappings if a process is swapped out, this will free page
* table pages.
*/
if (desired == 0 && nothingwired) {
pmap_remove(vm_map_pmap(map), vm_map_min(map),
vm_map_max(map));
}
vm_map_unlock(map);
}
#endif /* !defined(NO_SWAPPING) */
/*
* vm_pageout_scan does the dirty work for the pageout daemon.
*
* pass 0 - Update active LRU/deactivate pages
* pass 1 - Move inactive to cache or free
* pass 2 - Launder dirty pages
*/
static void
vm_pageout_scan(struct vm_domain *vmd, int pass)
{
vm_page_t m, next;
struct vm_pagequeue *pq;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
vm_object_t object;
int act_delta, addl_page_shortage, deficit, maxscan, page_shortage;
int vnodes_skipped = 0;
int maxlaunder;
int lockmode;
boolean_t queues_locked;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
/*
* If we need to reclaim memory ask kernel caches to return
* some. We rate limit to avoid thrashing.
*/
if (vmd == &vm_dom[0] && pass > 0 &&
(ticks - lowmem_ticks) / hz >= lowmem_period) {
/*
* Decrease registered cache sizes.
*/
SDT_PROBE0(vm, , , vm__lowmem_scan);
EVENTHANDLER_INVOKE(vm_lowmem, 0);
/*
* We do this explicitly after the caches have been
* drained above.
*/
uma_reclaim();
lowmem_ticks = ticks;
}
/*
* The addl_page_shortage is the number of temporarily
* stuck pages in the inactive queue. In other words, the
* number of pages from the inactive count that should be
* discounted in setting the target for the active queue scan.
*/
addl_page_shortage = 0;
/*
* Calculate the number of pages we want to either free or move
* to the cache.
*/
if (pass > 0) {
deficit = atomic_readandclear_int(&vm_pageout_deficit);
page_shortage = vm_paging_target() + deficit;
} else
page_shortage = deficit = 0;
/*
* maxlaunder limits the number of dirty pages we flush per scan.
* For most systems a smaller value (16 or 32) is more robust under
* extreme memory and disk pressure because any unnecessary writes
* to disk can result in extreme performance degredation. However,
* systems with excessive dirty pages (especially when MAP_NOSYNC is
* used) will die horribly with limited laundering. If the pageout
* daemon cannot clean enough pages in the first pass, we let it go
* all out in succeeding passes.
*/
if ((maxlaunder = vm_max_launder) <= 1)
maxlaunder = 1;
if (pass > 1)
maxlaunder = 10000;
/*
* Start scanning the inactive queue for pages we can move to the
* cache or free. The scan will stop when the target is reached or
* we have scanned the entire inactive queue. Note that m->act_count
* is not used to form decisions for the inactive queue, only for the
* active queue.
*/
pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
maxscan = pq->pq_cnt;
vm_pagequeue_lock(pq);
queues_locked = TRUE;
for (m = TAILQ_FIRST(&pq->pq_pl);
The buffer queue mechanism has been reformulated. Instead of having QUEUE_AGE, QUEUE_LRU, and QUEUE_EMPTY we instead have QUEUE_CLEAN, QUEUE_DIRTY, QUEUE_EMPTY, and QUEUE_EMPTYKVA. With this patch clean and dirty buffers have been separated. Empty buffers with KVM assignments have been separated from truely empty buffers. getnewbuf() has been rewritten and now operates in a 100% optimal fashion. That is, it is able to find precisely the right kind of buffer it needs to allocate a new buffer, defragment KVM, or to free-up an existing buffer when the buffer cache is full (which is a steady-state situation for the buffer cache). Buffer flushing has been reorganized. Previously buffers were flushed in the context of whatever process hit the conditions forcing buffer flushing to occur. This resulted in processes blocking on conditions unrelated to what they were doing. This also resulted in inappropriate VFS stacking chains due to multiple processes getting stuck trying to flush dirty buffers or due to a single process getting into a situation where it might attempt to flush buffers recursively - a situation that was only partially fixed in prior commits. We have added a new daemon called the buf_daemon which is responsible for flushing dirty buffers when the number of dirty buffers exceeds the vfs.hidirtybuffers limit. This daemon attempts to dynamically adjust the rate at which dirty buffers are flushed such that getnewbuf() calls (almost) never block. The number of nbufs and amount of buffer space is now scaled past the 8MB limit that was previously imposed for systems with over 64MB of memory, and the vfs.{lo,hi}dirtybuffers limits have been relaxed somewhat. The number of physical buffers has been increased with the intention that we will manage physical I/O differently in the future. reassignbuf previously attempted to keep the dirtyblkhd list sorted which could result in non-deterministic operation under certain conditions, such as when a large number of dirty buffers are being managed. This algorithm has been changed. reassignbuf now keeps buffers locally sorted if it can do so cheaply, and otherwise gives up and adds buffers to the head of the dirtyblkhd list. The new algorithm is deterministic but not perfect. The new algorithm greatly reduces problems that previously occured when write_behind was turned off in the system. The P_FLSINPROG proc->p_flag bit has been replaced by the more descriptive P_BUFEXHAUST bit. This bit allows processes working with filesystem buffers to use available emergency reserves. Normal processes do not set this bit and are not allowed to dig into emergency reserves. The purpose of this bit is to avoid low-memory deadlocks. A small race condition was fixed in getpbuf() in vm/vm_pager.c. Submitted by: Matthew Dillon <dillon@apollo.backplane.com> Reviewed by: Kirk McKusick <mckusick@mckusick.com>
1999-07-04 00:25:38 +00:00
m != NULL && maxscan-- > 0 && page_shortage > 0;
m = next) {
vm_pagequeue_assert_locked(pq);
KASSERT(queues_locked, ("unlocked queues"));
KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m));
1994-05-24 10:09:53 +00:00
PCPU_INC(cnt.v_pdpages);
next = TAILQ_NEXT(m, plinks.q);
1994-05-24 10:09:53 +00:00
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
/*
* skip marker pages
*/
if (m->flags & PG_MARKER)
continue;
KASSERT((m->flags & PG_FICTITIOUS) == 0,
("Fictitious page %p cannot be in inactive queue", m));
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
("Unmanaged page %p cannot be in inactive queue", m));
/*
* The page or object lock acquisitions fail if the
* page was removed from the queue or moved to a
* different position within the queue. In either
* case, addl_page_shortage should not be incremented.
*/
if (!vm_pageout_page_lock(m, &next)) {
vm_page_unlock(m);
continue;
}
object = m->object;
if (!VM_OBJECT_TRYWLOCK(object) &&
!vm_pageout_fallback_object_lock(m, &next)) {
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
continue;
}
1994-05-24 10:09:53 +00:00
/*
* Don't mess with busy pages, keep them at at the
* front of the queue, most likely they are being
* paged out. Increment addl_page_shortage for busy
* pages, because they may leave the inactive queue
* shortly after page scan is finished.
1994-05-24 10:09:53 +00:00
*/
if (vm_page_busied(m)) {
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
addl_page_shortage++;
continue;
}
/*
* We unlock the inactive page queue, invalidating the
* 'next' pointer. Use our marker to remember our
* place.
*/
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q);
vm_pagequeue_unlock(pq);
queues_locked = FALSE;
/*
* We bump the activation count if the page has been
* referenced while in the inactive queue. This makes
* it less likely that the page will be added back to the
* inactive queue prematurely again. Here we check the
* page tables (or emulated bits, if any), given the upper
* level VM system not knowing anything about existing
* references.
*/
if ((m->aflags & PGA_REFERENCED) != 0) {
vm_page_aflag_clear(m, PGA_REFERENCED);
act_delta = 1;
} else
act_delta = 0;
if (object->ref_count != 0) {
act_delta += pmap_ts_referenced(m);
} else {
KASSERT(!pmap_page_is_mapped(m),
("vm_pageout_scan: page %p is mapped", m));
}
/*
* If the upper level VM system knows about any page
* references, we reactivate the page or requeue it.
*/
if (act_delta != 0) {
if (object->ref_count != 0) {
vm_page_activate(m);
m->act_count += act_delta + ACT_ADVANCE;
} else {
vm_pagequeue_lock(pq);
queues_locked = TRUE;
vm_page_requeue_locked(m);
}
VM_OBJECT_WUNLOCK(object);
vm_page_unlock(m);
goto relock_queues;
}
if (m->hold_count != 0) {
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
/*
* Held pages are essentially stuck in the
* queue. So, they ought to be discounted
* from the inactive count. See the
* calculation of the page_shortage for the
* loop over the active queue below.
*/
addl_page_shortage++;
goto relock_queues;
}
/*
* If the page appears to be clean at the machine-independent
* layer, then remove all of its mappings from the pmap in
* anticipation of placing it onto the cache queue. If,
* however, any of the page's mappings allow write access,
* then the page may still be modified until the last of those
* mappings are removed.
*/
vm_page_test_dirty(m);
if (m->dirty == 0 && object->ref_count != 0)
pmap_remove_all(m);
if (m->valid == 0) {
/*
* Invalid pages can be easily freed
*/
vm_page_free(m);
PCPU_INC(cnt.v_dfree);
--page_shortage;
} else if (m->dirty == 0) {
/*
* Clean pages can be placed onto the cache queue.
* This effectively frees them.
*/
vm_page_cache(m);
--page_shortage;
} else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) {
/*
* Dirty pages need to be paged out, but flushing
2014-01-21 03:27:47 +00:00
* a page is extremely expensive versus freeing
* a clean page. Rather then artificially limiting
* the number of pages we can flush, we instead give
* dirty pages extra priority on the inactive queue
* by forcing them to be cycled through the queue
* twice before being flushed, after which the
* (now clean) page will cycle through once more
* before being freed. This significantly extends
* the thrash point for a heavily loaded machine.
*/
m->flags |= PG_WINATCFLS;
vm_pagequeue_lock(pq);
queues_locked = TRUE;
vm_page_requeue_locked(m);
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
} else if (maxlaunder > 0) {
/*
* We always want to try to flush some dirty pages if
* we encounter them, to keep the system stable.
* Normally this number is small, but under extreme
* pressure where there are insufficient clean pages
* on the inactive queue, we may have to go all out.
*/
int swap_pageouts_ok;
struct vnode *vp = NULL;
struct mount *mp = NULL;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
swap_pageouts_ok = 1;
} else {
swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
vm_page_count_min());
}
/*
* We don't bother paging objects that are "dead".
* Those objects are in a "rundown" state.
*/
if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
vm_pagequeue_lock(pq);
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
queues_locked = TRUE;
vm_page_requeue_locked(m);
goto relock_queues;
}
/*
* The object is already known NOT to be dead. It
* is possible for the vget() to block the whole
* pageout daemon, but the new low-memory handling
* code should prevent it.
*
* The previous code skipped locked vnodes and, worse,
* reordered pages in the queue. This results in
* completely non-deterministic operation and, on a
* busy system, can lead to extremely non-optimal
* pageouts. For example, it can cause clean pages
* to be freed and dirty pages to be moved to the end
* of the queue. Since dirty pages are also moved to
* the end of the queue once-cleaned, this gives
2014-01-21 03:27:47 +00:00
* way too large a weighting to deferring the freeing
* of dirty pages.
*
* We can't wait forever for the vnode lock, we might
* deadlock due to a vn_read() getting stuck in
* vm_wait while holding this vnode. We skip the
* vnode if we can't get it in a reasonable amount
* of time.
*/
if (object->type == OBJT_VNODE) {
vm_page_unlock(m);
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
vp = object->handle;
if (vp->v_type == VREG &&
vn_start_write(vp, &mp, V_NOWAIT) != 0) {
mp = NULL;
++pageout_lock_miss;
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
goto unlock_and_continue;
}
KASSERT(mp != NULL,
("vp %p with NULL v_mount", vp));
vm_object_reference_locked(object);
VM_OBJECT_WUNLOCK(object);
lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
LK_SHARED : LK_EXCLUSIVE;
if (vget(vp, lockmode | LK_TIMELOCK,
curthread)) {
VM_OBJECT_WLOCK(object);
++pageout_lock_miss;
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
vp = NULL;
goto unlock_and_continue;
}
VM_OBJECT_WLOCK(object);
vm_page_lock(m);
vm_pagequeue_lock(pq);
queues_locked = TRUE;
/*
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
* The page might have been moved to another
* queue during potential blocking in vget()
* above. The page might have been freed and
* reused for another vnode.
*/
if (m->queue != PQ_INACTIVE ||
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
m->object != object ||
TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) {
vm_page_unlock(m);
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
goto unlock_and_continue;
}
/*
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
* The page may have been busied during the
* blocking in vget(). We don't move the
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
* page back onto the end of the queue so that
* statistics are more correct if we don't.
*/
if (vm_page_busied(m)) {
vm_page_unlock(m);
addl_page_shortage++;
goto unlock_and_continue;
}
/*
* If the page has become held it might
* be undergoing I/O, so skip it
*/
if (m->hold_count != 0) {
vm_page_unlock(m);
addl_page_shortage++;
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
goto unlock_and_continue;
}
vm_pagequeue_unlock(pq);
queues_locked = FALSE;
}
/*
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
* If a page is dirty, then it is either being washed
* (but not yet cleaned) or it is still in the
* laundry. If it is still in the laundry, then we
* start the cleaning operation.
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
*
* decrement page_shortage on success to account for
* the (future) cleaned page. Otherwise we could wind
* up laundering or cleaning too many pages.
*/
if (vm_pageout_clean(m) != 0) {
--page_shortage;
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
--maxlaunder;
}
unlock_and_continue:
vm_page_lock_assert(m, MA_NOTOWNED);
VM_OBJECT_WUNLOCK(object);
if (mp != NULL) {
if (queues_locked) {
vm_pagequeue_unlock(pq);
queues_locked = FALSE;
}
if (vp != NULL)
vput(vp);
vm_object_deallocate(object);
vn_finished_write(mp);
}
vm_page_lock_assert(m, MA_NOTOWNED);
goto relock_queues;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
}
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
relock_queues:
if (!queues_locked) {
vm_pagequeue_lock(pq);
queues_locked = TRUE;
}
next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q);
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q);
}
vm_pagequeue_unlock(pq);
1994-05-24 10:09:53 +00:00
#if !defined(NO_SWAPPING)
/*
* Wakeup the swapout daemon if we didn't cache or free the targeted
* number of pages.
*/
if (vm_swap_enabled && page_shortage > 0)
vm_req_vmdaemon(VM_SWAP_NORMAL);
#endif
/*
* Wakeup the sync daemon if we skipped a vnode in a writeable object
* and we didn't cache or free enough pages.
*/
if (vnodes_skipped > 0 && page_shortage > vm_cnt.v_free_target -
vm_cnt.v_free_min)
(void)speedup_syncer();
/*
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
* Compute the number of pages we want to try to move from the
* active queue to the inactive queue.
1994-05-24 10:09:53 +00:00
*/
page_shortage = vm_cnt.v_inactive_target - vm_cnt.v_inactive_count +
vm_paging_target() + deficit + addl_page_shortage;
pq = &vmd->vmd_pagequeues[PQ_ACTIVE];
vm_pagequeue_lock(pq);
maxscan = pq->pq_cnt;
/*
* If we're just idle polling attempt to visit every
* active page within 'update_period' seconds.
*/
if (pass == 0 && vm_pageout_update_period != 0) {
maxscan /= vm_pageout_update_period;
page_shortage = maxscan;
}
/*
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
* Scan the active queue for things we can deactivate. We nominally
* track the per-page activity counter and use it to locate
* deactivation candidates.
*/
m = TAILQ_FIRST(&pq->pq_pl);
while (m != NULL && maxscan-- > 0 && page_shortage > 0) {
KASSERT(m->queue == PQ_ACTIVE,
("vm_pageout_scan: page %p isn't active", m));
next = TAILQ_NEXT(m, plinks.q);
if ((m->flags & PG_MARKER) != 0) {
m = next;
continue;
}
KASSERT((m->flags & PG_FICTITIOUS) == 0,
("Fictitious page %p cannot be in active queue", m));
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
("Unmanaged page %p cannot be in active queue", m));
Eliminate checks for a page having a NULL object in vm_pageout_scan() and vm_pageout_page_stats(). These checks were recently introduced by the first page locking commit, r207410, but they are not needed. At the same time, eliminate some redundant accesses to the page's object field. (These accesses should have neen eliminated by r207410.) Make the assertion in vm_page_flag_set() stricter. Specifically, only managed pages should have PG_WRITEABLE set. Add a comment documenting an assertion to vm_page_flag_clear(). It has long been the case that fictitious pages have their wire count permanently set to one. Add comments to vm_page_wire() and vm_page_unwire() documenting this. Add assertions to these functions as well. Update the comment describing vm_page_unwire(). Much of the old comment had little to do with vm_page_unwire(), but a lot to do with _vm_page_deactivate(). Move relevant parts of the old comment to _vm_page_deactivate(). Only pages that belong to an object can be paged out. Therefore, it is pointless for vm_page_unwire() to acquire the page queues lock and enqueue such pages in one of the paging queues. Generally speaking, such pages are immediately freed after the call to vm_page_unwire(). Previously, it was the call to vm_page_free() that reacquired the page queues lock and removed these pages from the paging queues. Now, we will never acquire the page queues lock for this case. (It is also worth noting that since both vm_page_unwire() and vm_page_free() occurred with the page locked, the page daemon never saw the page with its object field set to NULL.) Change the panic with vm_page_unwire() to provide a more precise message. Reviewed by: kib@
2010-06-14 19:54:19 +00:00
if (!vm_pageout_page_lock(m, &next)) {
vm_page_unlock(m);
m = next;
continue;
}
This set of commits to the VM system does the following, and contain contributions or ideas from Stephen McKay <syssgm@devetir.qld.gov.au>, Alan Cox <alc@cs.rice.edu>, David Greenman <davidg@freebsd.org> and me: More usage of the TAILQ macros. Additional minor fix to queue.h. Performance enhancements to the pageout daemon. Addition of a wait in the case that the pageout daemon has to run immediately. Slightly modify the pageout algorithm. Significant revamp of the pmap/fork code: 1) PTE's and UPAGES's are NO LONGER in the process's map. 2) PTE's and UPAGES's reside in their own objects. 3) TOTAL elimination of recursive page table pagefaults. 4) The page directory now resides in the PTE object. 5) Implemented pmap_copy, thereby speeding up fork time. 6) Changed the pv entries so that the head is a pointer and not an entire entry. 7) Significant cleanup of pmap_protect, and pmap_remove. 8) Removed significant amounts of machine dependent fork code from vm_glue. Pushed much of that code into the machine dependent pmap module. 9) Support more completely the reuse of already zeroed pages (Page table pages and page directories) as being already zeroed. Performance and code cleanups in vm_map: 1) Improved and simplified allocation of map entries. 2) Improved vm_map_copy code. 3) Corrected some minor problems in the simplify code. Implemented splvm (combo of splbio and splimp.) The VM code now seldom uses splhigh. Improved the speed of and simplified kmem_malloc. Minor mod to vm_fault to avoid using pre-zeroed pages in the case of objects with backing objects along with the already existant condition of having a vnode. (If there is a backing object, there will likely be a COW... With a COW, it isn't necessary to start with a pre-zeroed page.) Minor reorg of source to perhaps improve locality of ref.
1996-05-18 03:38:05 +00:00
/*
* The count for pagedaemon pages is done after checking the
2000-03-26 15:20:23 +00:00
* page for eligibility...
This set of commits to the VM system does the following, and contain contributions or ideas from Stephen McKay <syssgm@devetir.qld.gov.au>, Alan Cox <alc@cs.rice.edu>, David Greenman <davidg@freebsd.org> and me: More usage of the TAILQ macros. Additional minor fix to queue.h. Performance enhancements to the pageout daemon. Addition of a wait in the case that the pageout daemon has to run immediately. Slightly modify the pageout algorithm. Significant revamp of the pmap/fork code: 1) PTE's and UPAGES's are NO LONGER in the process's map. 2) PTE's and UPAGES's reside in their own objects. 3) TOTAL elimination of recursive page table pagefaults. 4) The page directory now resides in the PTE object. 5) Implemented pmap_copy, thereby speeding up fork time. 6) Changed the pv entries so that the head is a pointer and not an entire entry. 7) Significant cleanup of pmap_protect, and pmap_remove. 8) Removed significant amounts of machine dependent fork code from vm_glue. Pushed much of that code into the machine dependent pmap module. 9) Support more completely the reuse of already zeroed pages (Page table pages and page directories) as being already zeroed. Performance and code cleanups in vm_map: 1) Improved and simplified allocation of map entries. 2) Improved vm_map_copy code. 3) Corrected some minor problems in the simplify code. Implemented splvm (combo of splbio and splimp.) The VM code now seldom uses splhigh. Improved the speed of and simplified kmem_malloc. Minor mod to vm_fault to avoid using pre-zeroed pages in the case of objects with backing objects along with the already existant condition of having a vnode. (If there is a backing object, there will likely be a COW... With a COW, it isn't necessary to start with a pre-zeroed page.) Minor reorg of source to perhaps improve locality of ref.
1996-05-18 03:38:05 +00:00
*/
PCPU_INC(cnt.v_pdpages);
/*
* Check to see "how much" the page has been used.
*/
if ((m->aflags & PGA_REFERENCED) != 0) {
vm_page_aflag_clear(m, PGA_REFERENCED);
act_delta = 1;
} else
act_delta = 0;
/*
* Unlocked object ref count check. Two races are possible.
* 1) The ref was transitioning to zero and we saw non-zero,
* the pmap bits will be checked unnecessarily.
* 2) The ref was transitioning to one and we saw zero.
* The page lock prevents a new reference to this page so
* we need not check the reference bits.
*/
if (m->object->ref_count != 0)
act_delta += pmap_ts_referenced(m);
/*
* Advance or decay the act_count based on recent usage.
*/
if (act_delta != 0) {
m->act_count += ACT_ADVANCE + act_delta;
if (m->act_count > ACT_MAX)
m->act_count = ACT_MAX;
} else
m->act_count -= min(m->act_count, ACT_DECLINE);
/*
* Move this page to the tail of the active or inactive
* queue depending on usage.
*/
if (m->act_count == 0) {
/* Dequeue to avoid later lock recursion. */
vm_page_dequeue_locked(m);
vm_page_deactivate(m);
page_shortage--;
} else
vm_page_requeue_locked(m);
vm_page_unlock(m);
m = next;
1994-05-24 10:09:53 +00:00
}
vm_pagequeue_unlock(pq);
#if !defined(NO_SWAPPING)
/*
* Idle process swapout -- run once per second.
*/
if (vm_swap_idle_enabled) {
static long lsec;
if (time_second != lsec) {
vm_req_vmdaemon(VM_SWAP_IDLE);
lsec = time_second;
}
}
#endif
/*
* If we are critically low on one of RAM or swap and low on
* the other, kill the largest process. However, we avoid
* doing this on the first pass in order to give ourselves a
* chance to flush out dirty vnode-backed pages and to allow
* active pages to be moved to the inactive queue and reclaimed.
*/
vm_pageout_mightbe_oom(vmd, pass);
}
static int vm_pageout_oom_vote;
/*
* The pagedaemon threads randlomly select one to perform the
* OOM. Trying to kill processes before all pagedaemons
* failed to reach free target is premature.
*/
static void
vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass)
{
int old_vote;
if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) ||
(swap_pager_full && vm_paging_target() > 0))) {
if (vmd->vmd_oom) {
vmd->vmd_oom = FALSE;
atomic_subtract_int(&vm_pageout_oom_vote, 1);
}
return;
}
if (vmd->vmd_oom)
return;
vmd->vmd_oom = TRUE;
old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1);
if (old_vote != vm_ndomains - 1)
return;
/*
* The current pagedaemon thread is the last in the quorum to
* start OOM. Initiate the selection and signaling of the
* victim.
*/
vm_pageout_oom(VM_OOM_MEM);
/*
* After one round of OOM terror, recall our vote. On the
* next pass, current pagedaemon would vote again if the low
* memory condition is still there, due to vmd_oom being
* false.
*/
vmd->vmd_oom = FALSE;
atomic_subtract_int(&vm_pageout_oom_vote, 1);
}
void
vm_pageout_oom(int shortage)
{
struct proc *p, *bigproc;
vm_offset_t size, bigsize;
struct thread *td;
struct vmspace *vm;
/*
* We keep the process bigproc locked once we find it to keep anyone
* from messing with it; however, there is a possibility of
* deadlock if process B is bigproc and one of it's child processes
* attempts to propagate a signal to B while we are waiting for A's
* lock while walking this list. To avoid this, we don't block on
* the process lock but just skip a process if it is already locked.
*/
bigproc = NULL;
bigsize = 0;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
int breakout;
if (PROC_TRYLOCK(p) == 0)
continue;
/*
* If this is a system, protected or killed process, skip it.
*/
if (p->p_state != PRS_NORMAL ||
(p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) ||
(p->p_pid == 1) || P_KILLED(p) ||
((p->p_pid < 48) && (swap_pager_avail != 0))) {
PROC_UNLOCK(p);
continue;
}
/*
* If the process is in a non-running type state,
* don't touch it. Check all the threads individually.
*/
breakout = 0;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (!TD_ON_RUNQ(td) &&
!TD_IS_RUNNING(td) &&
!TD_IS_SLEEPING(td) &&
!TD_IS_SUSPENDED(td)) {
thread_unlock(td);
breakout = 1;
break;
}
thread_unlock(td);
}
if (breakout) {
PROC_UNLOCK(p);
continue;
}
/*
* get the process size
*/
vm = vmspace_acquire_ref(p);
if (vm == NULL) {
PROC_UNLOCK(p);
continue;
}
if (!vm_map_trylock_read(&vm->vm_map)) {
vmspace_free(vm);
PROC_UNLOCK(p);
continue;
}
size = vmspace_swap_count(vm);
vm_map_unlock_read(&vm->vm_map);
if (shortage == VM_OOM_MEM)
size += vmspace_resident_count(vm);
vmspace_free(vm);
/*
* if the this process is bigger than the biggest one
* remember it.
*/
if (size > bigsize) {
if (bigproc != NULL)
PROC_UNLOCK(bigproc);
bigproc = p;
bigsize = size;
} else
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
if (bigproc != NULL) {
killproc(bigproc, "out of swap space");
sched_nice(bigproc, PRIO_MIN);
PROC_UNLOCK(bigproc);
wakeup(&vm_cnt.v_free_count);
}
}
1994-05-24 10:09:53 +00:00
static void
vm_pageout_worker(void *arg)
{
struct vm_domain *domain;
int domidx;
domidx = (uintptr_t)arg;
domain = &vm_dom[domidx];
/*
* XXXKIB It could be useful to bind pageout daemon threads to
* the cores belonging to the domain, from which vm_page_array
* is allocated.
*/
KASSERT(domain->vmd_segs != 0, ("domain without segments"));
vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE);
/*
* The pageout daemon worker is never done, so loop forever.
*/
while (TRUE) {
/*
* If we have enough free memory, wakeup waiters. Do
* not clear vm_pages_needed until we reach our target,
* otherwise we may be woken up over and over again and
* waste a lot of cpu.
*/
mtx_lock(&vm_page_queue_free_mtx);
if (vm_pages_needed && !vm_page_count_min()) {
if (!vm_paging_needed())
vm_pages_needed = 0;
wakeup(&vm_cnt.v_free_count);
}
if (vm_pages_needed) {
/*
* Still not done, take a second pass without waiting
* (unlimited dirty cleaning), otherwise sleep a bit
* and try again.
*/
if (domain->vmd_pass > 1)
msleep(&vm_pages_needed,
&vm_page_queue_free_mtx, PVM, "psleep",
hz / 2);
} else {
/*
* Good enough, sleep until required to refresh
* stats.
*/
domain->vmd_pass = 0;
msleep(&vm_pages_needed, &vm_page_queue_free_mtx,
PVM, "psleep", hz);
}
if (vm_pages_needed) {
vm_cnt.v_pdwakeups++;
domain->vmd_pass++;
}
mtx_unlock(&vm_page_queue_free_mtx);
vm_pageout_scan(domain, domain->vmd_pass);
}
}
1994-05-24 10:09:53 +00:00
/*
* vm_pageout_init initialises basic pageout daemon settings.
1994-05-24 10:09:53 +00:00
*/
static void
vm_pageout_init(void)
1994-05-24 10:09:53 +00:00
{
/*
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
* Initialize some paging parameters.
1994-05-24 10:09:53 +00:00
*/
vm_cnt.v_interrupt_free_min = 2;
if (vm_cnt.v_page_count < 2000)
vm_pageout_page_count = 8;
/*
* v_free_reserved needs to include enough for the largest
* swap pager structures plus enough for any pv_entry structs
* when paging.
*/
if (vm_cnt.v_page_count > 1024)
vm_cnt.v_free_min = 4 + (vm_cnt.v_page_count - 1024) / 200;
else
vm_cnt.v_free_min = 4;
vm_cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
vm_cnt.v_interrupt_free_min;
vm_cnt.v_free_reserved = vm_pageout_page_count +
vm_cnt.v_pageout_free_min + (vm_cnt.v_page_count / 768);
vm_cnt.v_free_severe = vm_cnt.v_free_min / 2;
vm_cnt.v_free_target = 4 * vm_cnt.v_free_min + vm_cnt.v_free_reserved;
vm_cnt.v_free_min += vm_cnt.v_free_reserved;
vm_cnt.v_free_severe += vm_cnt.v_free_reserved;
vm_cnt.v_inactive_target = (3 * vm_cnt.v_free_target) / 2;
if (vm_cnt.v_inactive_target > vm_cnt.v_free_count / 3)
vm_cnt.v_inactive_target = vm_cnt.v_free_count / 3;
/*
* Set the default wakeup threshold to be 10% above the minimum
* page limit. This keeps the steady state out of shortfall.
*/
vm_pageout_wakeup_thresh = (vm_cnt.v_free_min / 10) * 11;
/*
* Set interval in seconds for active scan. We want to visit each
* page at least once every ten minutes. This is to prevent worst
* case paging behaviors with stale active LRU.
*/
if (vm_pageout_update_period == 0)
vm_pageout_update_period = 600;
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
/* XXX does not really belong here */
1994-05-24 10:09:53 +00:00
if (vm_page_max_wired == 0)
vm_page_max_wired = vm_cnt.v_free_count / 3;
}
/*
* vm_pageout is the high level pageout daemon.
*/
static void
vm_pageout(void)
{
#if MAXMEMDOM > 1
int error, i;
#endif
1994-05-24 10:09:53 +00:00
NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct proc or any VM system structure will have to be rebuilt!!! Much needed overhaul of the VM system. Included in this first round of changes: 1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages, haspage, and sync operations are supported. The haspage interface now provides information about clusterability. All pager routines now take struct vm_object's instead of "pagers". 2) Improved data structures. In the previous paradigm, there is constant confusion caused by pagers being both a data structure ("allocate a pager") and a collection of routines. The idea of a pager structure has escentially been eliminated. Objects now have types, and this type is used to index the appropriate pager. In most cases, items in the pager structure were duplicated in the object data structure and thus were unnecessary. In the few cases that remained, a un_pager structure union was created in the object to contain these items. 3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now be removed. For instance, vm_object_enter(), vm_object_lookup(), vm_object_remove(), and the associated object hash list were some of the things that were removed. 4) simple_lock's removed. Discussion with several people reveals that the SMP locking primitives used in the VM system aren't likely the mechanism that we'll be adopting. Even if it were, the locking that was in the code was very inadequate and would have to be mostly re-done anyway. The locking in a uni-processor kernel was a no-op but went a long way toward making the code difficult to read and debug. 5) Places that attempted to kludge-up the fact that we don't have kernel thread support have been fixed to reflect the reality that we are really dealing with processes, not threads. The VM system didn't have complete thread support, so the comments and mis-named routines were just wrong. We now use tsleep and wakeup directly in the lock routines, for instance. 6) Where appropriate, the pagers have been improved, especially in the pager_alloc routines. Most of the pager_allocs have been rewritten and are now faster and easier to maintain. 7) The pagedaemon pageout clustering algorithm has been rewritten and now tries harder to output an even number of pages before and after the requested page. This is sort of the reverse of the ideal pagein algorithm and should provide better overall performance. 8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup have been removed. Some other unnecessary casts have also been removed. 9) Some almost useless debugging code removed. 10) Terminology of shadow objects vs. backing objects straightened out. The fact that the vm_object data structure escentially had this backwards really confused things. The use of "shadow" and "backing object" throughout the code is now internally consistent and correct in the Mach terminology. 11) Several minor bug fixes, including one in the vm daemon that caused 0 RSS objects to not get purged as intended. 12) A "default pager" has now been created which cleans up the transition of objects to the "swap" type. The previous checks throughout the code for swp->pg_data != NULL were really ugly. This change also provides the rudiments for future backing of "anonymous" memory by something other than the swap pager (via the vnode pager, for example), and it allows the decision about which of these pagers to use to be made dynamically (although will need some additional decision code to do this, of course). 13) (dyson) MAP_COPY has been deprecated and the corresponding "copy object" code has been removed. MAP_COPY was undocumented and non- standard. It was furthermore broken in several ways which caused its behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will continue to work correctly, but via the slightly different semantics of MAP_PRIVATE. 14) (dyson) Sharing maps have been removed. It's marginal usefulness in a threads design can be worked around in other ways. Both #12 and #13 were done to simplify the code and improve readability and maintain- ability. (As were most all of these changes) TODO: 1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing this will reduce the vnode pager to a mere fraction of its current size. 2) Rewrite vm_fault and the swap/vnode pagers to use the clustering information provided by the new haspage pager interface. This will substantially reduce the overhead by eliminating a large number of VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be improved to provide both a "behind" and "ahead" indication of contiguousness. 3) Implement the extended features of pager_haspage in swap_pager_haspage(). It currently just says 0 pages ahead/behind. 4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps via a much more general mechanism that could also be used for disk striping of regular filesystems. 5) Do something to improve the architecture of vm_object_collapse(). The fact that it makes calls into the swap pager and knows too much about how the swap pager operates really bothers me. It also doesn't allow for collapsing of non-swap pager objects ("unnamed" objects backed by other pagers).
1995-07-13 08:48:48 +00:00
swap_pager_swap_init();
#if MAXMEMDOM > 1
for (i = 1; i < vm_ndomains; i++) {
error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i,
curproc, NULL, 0, 0, "dom%d", i);
if (error != 0) {
panic("starting pageout for domain %d, error %d\n",
i, error);
Implement a low-memory deadlock solution. Removed most of the hacks that were trying to deal with low-memory situations prior to now. The new code is based on the concept that I/O must be able to function in a low memory situation. All major modules related to I/O (except networking) have been adjusted to allow allocation out of the system reserve memory pool. These modules now detect a low memory situation but rather then block they instead continue to operate, then return resources to the memory pool instead of cache them or leave them wired. Code has been added to stall in a low-memory situation prior to a vnode being locked. Thus situations where a process blocks in a low-memory condition while holding a locked vnode have been reduced to near nothing. Not only will I/O continue to operate, but many prior deadlock conditions simply no longer exist. Implement a number of VFS/BIO fixes (found by Ian): in biodone(), bogus-page replacement code, the loop was not properly incrementing loop variables prior to a continue statement. We do not believe this code can be hit anyway but we aren't taking any chances. We'll turn the whole section into a panic (as it already is in brelse()) after the release is rolled. In biodone(), the foff calculation was incorrectly clamped to the iosize, causing the wrong foff to be calculated for pages in the case of an I/O error or biodone() called without initiating I/O. The problem always caused a panic before. Now it doesn't. The problem is mainly an issue with NFS. Fixed casts for ~PAGE_MASK. This code worked properly before only because the calculations use signed arithmatic. Better to properly extend PAGE_MASK first before inverting it for the 64 bit masking op. In brelse(), the bogus_page fixup code was improperly throwing away the original contents of 'm' when it did the j-loop to fix the bogus pages. The result was that it would potentially invalidate parts of the *WRONG* page(!), leading to corruption. There may still be cases where a background bitmap write is being duplicated, causing potential corruption. We have identified a potentially serious bug related to this but the fix is still TBD. So instead this patch contains a KASSERT to detect the problem and panic the machine rather then continue to corrupt the filesystem. The problem does not occur very often.. it is very hard to reproduce, and it may or may not be the cause of the corruption people have reported. Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>) Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
}
1994-05-24 10:09:53 +00:00
}
#endif
vm_pageout_worker((void *)(uintptr_t)0);
1994-05-24 10:09:53 +00:00
}
/*
* Unless the free page queue lock is held by the caller, this function
* should be regarded as advisory. Specifically, the caller should
* not msleep() on &vm_cnt.v_free_count following this function unless
* the free page queue lock is held until the msleep() is performed.
*/
void
2013-01-28 12:08:29 +00:00
pagedaemon_wakeup(void)
{
if (!vm_pages_needed && curthread->td_proc != pageproc) {
vm_pages_needed = 1;
wakeup(&vm_pages_needed);
}
}
#if !defined(NO_SWAPPING)
static void
vm_req_vmdaemon(int req)
{
static int lastrun = 0;
mtx_lock(&vm_daemon_mtx);
vm_pageout_req_swapout |= req;
This set of commits to the VM system does the following, and contain contributions or ideas from Stephen McKay <syssgm@devetir.qld.gov.au>, Alan Cox <alc@cs.rice.edu>, David Greenman <davidg@freebsd.org> and me: More usage of the TAILQ macros. Additional minor fix to queue.h. Performance enhancements to the pageout daemon. Addition of a wait in the case that the pageout daemon has to run immediately. Slightly modify the pageout algorithm. Significant revamp of the pmap/fork code: 1) PTE's and UPAGES's are NO LONGER in the process's map. 2) PTE's and UPAGES's reside in their own objects. 3) TOTAL elimination of recursive page table pagefaults. 4) The page directory now resides in the PTE object. 5) Implemented pmap_copy, thereby speeding up fork time. 6) Changed the pv entries so that the head is a pointer and not an entire entry. 7) Significant cleanup of pmap_protect, and pmap_remove. 8) Removed significant amounts of machine dependent fork code from vm_glue. Pushed much of that code into the machine dependent pmap module. 9) Support more completely the reuse of already zeroed pages (Page table pages and page directories) as being already zeroed. Performance and code cleanups in vm_map: 1) Improved and simplified allocation of map entries. 2) Improved vm_map_copy code. 3) Corrected some minor problems in the simplify code. Implemented splvm (combo of splbio and splimp.) The VM code now seldom uses splhigh. Improved the speed of and simplified kmem_malloc. Minor mod to vm_fault to avoid using pre-zeroed pages in the case of objects with backing objects along with the already existant condition of having a vnode. (If there is a backing object, there will likely be a COW... With a COW, it isn't necessary to start with a pre-zeroed page.) Minor reorg of source to perhaps improve locality of ref.
1996-05-18 03:38:05 +00:00
if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
wakeup(&vm_daemon_needed);
lastrun = ticks;
}
mtx_unlock(&vm_daemon_mtx);
}
static void
2013-01-28 12:08:29 +00:00
vm_daemon(void)
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
{
struct rlimit rsslim;
struct proc *p;
struct thread *td;
struct vmspace *vm;
int breakout, swapout_flags, tryagain, attempts;
#ifdef RACCT
uint64_t rsize, ravailable;
#endif
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
while (TRUE) {
mtx_lock(&vm_daemon_mtx);
#ifdef RACCT
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz);
#else
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0);
#endif
swapout_flags = vm_pageout_req_swapout;
vm_pageout_req_swapout = 0;
mtx_unlock(&vm_daemon_mtx);
if (swapout_flags)
swapout_procs(swapout_flags);
/*
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
* scan the processes for exceeding their rlimits or if
* process is swapped out -- deactivate pages
*/
tryagain = 0;
attempts = 0;
again:
attempts++;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
vm_pindex_t limit, size;
/*
* if this is a system process or if we have already
* looked at this process, skip it.
*/
PROC_LOCK(p);
if (p->p_state != PRS_NORMAL ||
p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
PROC_UNLOCK(p);
continue;
}
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
/*
* if the process is in a non-running type state,
* don't touch it.
*/
breakout = 0;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (!TD_ON_RUNQ(td) &&
!TD_IS_RUNNING(td) &&
!TD_IS_SLEEPING(td) &&
!TD_IS_SUSPENDED(td)) {
thread_unlock(td);
breakout = 1;
break;
}
thread_unlock(td);
}
if (breakout) {
PROC_UNLOCK(p);
continue;
}
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
/*
* get a limit
*/
lim_rlimit(p, RLIMIT_RSS, &rsslim);
limit = OFF_TO_IDX(
Locking for the per-process resource limits structure. - struct plimit includes a mutex to protect a reference count. The plimit structure is treated similarly to struct ucred in that is is always copy on write, so having a reference to a structure is sufficient to read from it without needing a further lock. - The proc lock protects the p_limit pointer and must be held while reading limits from a process to keep the limit structure from changing out from under you while reading from it. - Various global limits that are ints are not protected by a lock since int writes are atomic on all the archs we support and thus a lock wouldn't buy us anything. - All accesses to individual resource limits from a process are abstracted behind a simple lim_rlimit(), lim_max(), and lim_cur() API that return either an rlimit, or the current or max individual limit of the specified resource from a process. - dosetrlimit() was renamed to kern_setrlimit() to match existing style of other similar syscall helper functions. - The alpha OSF/1 compat layer no longer calls getrlimit() and setrlimit() (it didn't used the stackgap when it should have) but uses lim_rlimit() and kern_setrlimit() instead. - The svr4 compat no longer uses the stackgap for resource limits calls, but uses lim_rlimit() and kern_setrlimit() instead. - The ibcs2 compat no longer uses the stackgap for resource limits. It also no longer uses the stackgap for accessing sysctl's for the ibcs2_sysconf() syscall but uses kernel_sysctl() instead. As a result, ibcs2_sysconf() no longer needs Giant. - The p_rlimit macro no longer exists. Submitted by: mtm (mostly, I only did a few cleanups and catchups) Tested on: i386 Compiled on: alpha, amd64
2004-02-04 21:52:57 +00:00
qmin(rsslim.rlim_cur, rsslim.rlim_max));
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
/*
* let processes that are swapped out really be
* swapped out set the limit to nothing (will force a
* swap-out.)
*/
if ((p->p_flag & P_INMEM) == 0)
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
1995-01-09 16:06:02 +00:00
limit = 0; /* XXX */
vm = vmspace_acquire_ref(p);
PROC_UNLOCK(p);
if (vm == NULL)
continue;
size = vmspace_resident_count(vm);
if (size >= limit) {
vm_pageout_map_deactivate_pages(
&vm->vm_map, limit);
}
#ifdef RACCT
rsize = IDX_TO_OFF(size);
PROC_LOCK(p);
racct_set(p, RACCT_RSS, rsize);
ravailable = racct_get_available(p, RACCT_RSS);
PROC_UNLOCK(p);
if (rsize > ravailable) {
/*
* Don't be overly aggressive; this might be
* an innocent process, and the limit could've
* been exceeded by some memory hog. Don't
* try to deactivate more than 1/4th of process'
* resident set size.
*/
if (attempts <= 8) {
if (ravailable < rsize - (rsize / 4))
ravailable = rsize - (rsize / 4);
}
vm_pageout_map_deactivate_pages(
&vm->vm_map, OFF_TO_IDX(ravailable));
/* Update RSS usage after paging out. */
size = vmspace_resident_count(vm);
rsize = IDX_TO_OFF(size);
PROC_LOCK(p);
racct_set(p, RACCT_RSS, rsize);
PROC_UNLOCK(p);
if (rsize > ravailable)
tryagain = 1;
}
#endif
vmspace_free(vm);
}
sx_sunlock(&allproc_lock);
if (tryagain != 0 && attempts <= 10)
goto again;
}
}
#endif /* !defined(NO_SWAPPING) */