Commit Graph

312 Commits

Author SHA1 Message Date
John Baldwin
d071a6fa33 Another NFS SIGSTOP related fix: Ignore thread suspend requests due to
SIGSTOP if stop signals are currently deferred.  This can occur if a
process is stopped via SIGSTOP while a thread is running or runnable
but before it has set TDF_SBDRY.

Tested by:	pho
Reviewed by:	kib
MFC after:	1 week
2013-03-21 14:06:27 +00:00
John Baldwin
353374b525 Fix a few typos. 2013-02-19 16:35:27 +00:00
Konstantin Belousov
94cb35459d Make the updates of the tid ring buffer' head and tail pointers
explicit by moving them into separate statements from the buffer
element accesses.

Requested by:	jhb
MFC after:	3 days
2012-09-26 09:25:11 +00:00
Konstantin Belousov
787a64ddd2 Do not skip two elements of the tid_buffer when reusing the buffer
slot. This eventually results in exhaustion of the tid space, causing
new threads get tid -1 as identifier.

The bad effect of having the thread id equal to -1 is that
UMTX_OP_UMUTEX_WAIT returns EFAULT for a lock owned by such thread,
because casuword cannot distinguish between literal value -1 read from
the address and -1 returned as an indication of faulted
access. _thr_umutex_lock() helper from libthr does not check for
errors from _umtx_op_err(2), causing an infinite loop in
mutex_lock_sleep().

We observed the JVM processes hanging and consuming enormous amount of
system time on machines with approximately 100 days uptime.

Reported by:	Mykola Dzham <freebsd levsha org ua>
MFC after:	1 week
2012-09-22 12:17:09 +00:00
Attilio Rao
0a15e5d30d Remove all the checks on curthread != NULL with the exception of some MD
trap checks (eg. printtrap()).

Generally this check is not needed anymore, as there is not a legitimate
case where curthread != NULL, after pcpu 0 area has been properly
initialized.

Reviewed by:	bde, jhb
MFC after:	1 week
2012-09-13 22:26:22 +00:00
John Baldwin
773e3b7dda A few whitespace and comment fixes. 2012-09-07 15:10:46 +00:00
Konstantin Belousov
abce621c3a Fix grammar.
Submitted by:	jh
MFC after:	1 week
2012-08-16 13:01:56 +00:00
Konstantin Belousov
02c6fc2114 Add a sysctl kern.pid_max, which limits the maximum pid the system is
allowed to allocate, and corresponding tunable with the same
name. Note that existing processes with higher pids are left intact.

MFC after:	1 week
2012-08-15 15:56:21 +00:00
Konstantin Belousov
8f0e91308a Add a rangelock implementation, intended to be used to range-locking
the i/o regions of the vnode data space. The implementation is quite
simple-minded, it uses the list of the lock requests, ordered by
arrival time. Each request may be for read or for write. The
implementation is fair FIFO.

MFC after:     2 month
2012-05-30 16:06:38 +00:00
Ryan Stone
b3e9e682cf Implement the DTrace sched provider. This implementation aims to be
compatible with the sched provider implemented by Solaris and its open-
source derivatives.  Full documentation of the sched provider can be found
on Oracle's DTrace wiki pages.

Note that for compatibility with scripts originally written for Solaris,
serveral probes are defined that will never fire.  These probes are defined
to fire when Solaris-specific features perform certain actions.  As these
features are not present in FreeBSD, the probes can never fire.

Also, I have added a two probes that are not defined in Solaris, lend-pri
and load-change.  These probes have been added to make it possible to
collect schedgraph data with DTrace.

Finally, a few probes are defined in Solaris to take a cpuinfo_t *
argument.  As it was not immediately clear to me how to translate that to
FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *.

Sponsored by: Sandvine Incorporated
MFC after:	2 weeks
2012-05-15 01:30:25 +00:00
John Baldwin
7e3a96ea37 Some small fixes to CPU accounting for threads:
- Only initialize the per-cpu switchticks and switchtime in sched_throw()
  for the very first context switch on APs during boot.  This avoids a
  small gap between the middle of thread_exit() and sched_throw() where
  time is not accounted to any thread.
- In thread_exit(), update the timestamp bookkeeping to track the changes
  to mi_switch() introduced by td_rux so that the code once again matches
  the comment claiming it is mimicing mi_switch().  Specifically, only
  update the per-thread stats directly and depend on ruxagg() to update
  p_rux rather than adjusting p_rux directly.  While here, move the
  timestamp bookkeeping as late in the function as possible.

Reviewed by:	bde, kib
MFC after:	1 week
2012-01-03 21:03:28 +00:00
Konstantin Belousov
7b5190779b Consistently use process spin lock for protection of the
p->p_boundary_count. Race could cause the execve(2) from the threaded
process to hung since thread boundary counter was incorrect and
single-threading never finished.

Reported by:	pluknet, pho
Tested by:	pho
MFC after:	1 week
2011-11-18 09:12:26 +00:00
John Baldwin
8e6fa660f2 Fix some locking nits with the p_state field of struct proc:
- Hold the proc lock while changing the state from PRS_NEW to PRS_NORMAL
  in fork to honor the locking requirements.  While here, expand the scope
  of the PROC_LOCK() on the new process (p2) to avoid some LORs.  Previously
  the code was locking the new child process (p2) after it had locked the
  parent process (p1).  However, when locking two processes, the safe order
  is to lock the child first, then the parent.
- Fix various places that were checking p_state against PRS_NEW without
  having the process locked to use PROC_LOCK().  Every place was already
  locking the process, just after the PRS_NEW check.
- Remove or reduce the use of PROC_SLOCK() for places that were checking
  p_state against PRS_NEW.  The PROC_LOCK() alone is sufficient for reading
  the current state.
- Reorder fill_kinfo_proc() slightly so it only acquires PROC_SLOCK() once.

MFC after:	1 week
2011-03-24 18:40:11 +00:00
Sergey Kandaurov
c0bc8d1008 Clean up the now unused #include statement.
Approved by:	kib (mentor)
MFC after:	1 week
X-MFC with:	r218972
2011-02-23 18:22:40 +00:00
Konstantin Belousov
25a9cfc9e8 Move the max_threads_per_proc and max_threads_hits variables to the
file where they are used. Declare the kern.threads sysctl node at the
same location. Since no external use for the variables exists, make them
static.

Discussed with:	dchagin
MFC after:	1 week
2011-02-23 13:50:24 +00:00
David Xu
ec6ea5e86d MFp4:
The unit number allocator reuses ID too fast, this may hide bugs in
other code, add a ring buffer to delay freeing a thread ID.
2010-12-09 05:16:20 +00:00
David Xu
acbe332a58 MFp4:
It is possible a lower priority thread lending priority to higher priority
thread, in old code, it is ignored, however the lending should always be
recorded, add field td_lend_user_pri to fix the problem, if a thread does
not have borrowed priority, its value is PRI_MAX.

MFC after: 1 week
2010-12-09 02:42:02 +00:00
David Xu
21ecd1e977 - Insert thread0 into correct thread hash link list.
- In thr_exit() and kthread_exit(), only remove thread from
  hash if it can directly exit, otherwise let exit1() do it.
- In thread_suspend_check(), fix cleanup code when thread needs
  to exit.
This change seems fixed the "Bad link elm " panic found by
Peter Holm.

Stress testing: pho
2010-10-17 11:01:52 +00:00
David Xu
96f231fde9 Add a flag TDF_TIDHASH to prevent a thread from being
added to or removed from thread hash table multiple times.
2010-10-12 00:36:56 +00:00
David Xu
cf7d9a8ca8 Create a global thread hash table to speed up thread lookup, use
rwlock to protect the table. In old code, thread lookup is done with
process lock held, to find a thread, kernel has to iterate through
process and thread list, this is quite inefficient.
With this change, test shows in extreme case performance is
dramatically improved.

Earlier patch was reviewed by: jhb, julian
2010-10-09 02:50:23 +00:00
John Baldwin
f2a664ac97 Retire td_syscalls now that it is no longer needed. 2010-07-15 20:24:37 +00:00
Konstantin Belousov
41fd9c6369 Fix the double counting of the last process thread td_incruntime
on exit, that is done once in thread_exit() and the second time in
proc_reap(), by clearing td_incruntime.

Use the opportunity to revert to the pre-RUSAGE_THREAD exporting of ruxagg()
instead of ruxagg_locked() and use it from thread_exit().

Diagnosed and tested by:	neel
MFC after:	3 days
2010-05-24 10:23:49 +00:00
Konstantin Belousov
9182554ae9 Fix typo in comment.
MFC after:	3 days
2010-05-04 06:06:01 +00:00
Konstantin Belousov
603a4d7f41 Remove a comment that merely repeats code.
Submitted by:	bde
MFC after:	1 week
2010-05-04 06:04:33 +00:00
Konstantin Belousov
bed4c52416 Implement RUSAGE_THREAD. Add td_rux to keep extended runtime and ticks
information for thread to allow calcru1() (re)use.

Rename ruxagg()->ruxagg_locked(), ruxagg_tlock()->ruxagg() [1].
The ruxagg_locked() function no longer clears thread ticks nor
td_incruntime.

Requested by:	attilio [1]
Discussed with:	attilio, bde
Reviewed by:	bde
Based on submission by:	Alexander Krizhanovsky <ak natsys-lab com>
MFC after:	1 week
X-MFC-Note:	td_rux shall be moved to the end of struct thread
2010-05-04 05:55:37 +00:00
Joseph Koshy
16d95d4f92 Inform hwpmc(4) of a thread's impending demise prior to invoking sched_throw().
Debugging help:		fabient
Review and testing by:	fabient
2009-10-25 04:34:47 +00:00
Konstantin Belousov
8a945d109c Reintroduce the r196640, after fixing the problem with my testing.
Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stack size is equial to the
actual, and reallocate the stack if sizes differ [1].

This fixes the bug introduced by r173361 that was committed several days
after r173004 and consisted of kthread_add(9) ignoring the non-default
kernel stack size.

Also, r173361 removed the caching of the kernel stacks for a non-first
thread in the process. Introduce separate kernel stack cache that keeps
some limited amount of preallocated kernel stacks to lower the latency
of thread allocation. Add vm_lowmem handler to prune the cache on
low memory condition. This way, system with reasonable amount of the
threads get lower latency of thread creation, while still not exhausting
significant portion of KVA for unused kstacks.

Submitted by:	peter [1]
Discussed with:	jhb, julian, peter
Reviewed by:	jhb
Tested by:	pho (and retested according to new test scenarious)
MFC after:	1 week
2009-09-01 11:41:51 +00:00
Konstantin Belousov
f25fa6abb2 Reverse r196640 and r196644 for now. 2009-08-29 21:53:08 +00:00
Konstantin Belousov
c3cf0b476f Remove the altkstacks, instead instantiate threads with kernel stack
allocated with the right size from the start. For the thread that has
kernel stack cached, verify that requested stack size is equial to the
actual, and reallocate the stack if sizes differ [1].

This fixes the bug introduced by r173361 that was committed several days
after r173004 and consisted of kthread_add(9) ignoring the non-default
kernel stack size.

Also, r173361 removed the caching of the kernel stacks for a non-first
thread in the process. Introduce separate kernel stack cache that keeps
some limited amount of preallocated kernel stacks to lower the latency
of thread allocation. Add vm_lowmem handler to prune the cache on
low memory condition. This way, system with reasonable amount of the
threads get lower latency of thread creation, while still not exhausting
significant portion of KVA for unused kstacks.

Submitted by:	peter [1]
Discussed with:	jhb, julian, peter
Reviewed by:	jhb
Tested by:	pho
MFC after:	1 week
2009-08-29 13:28:02 +00:00
Konstantin Belousov
f33a947b56 Add new msleep(9) flag PBDY that shall be specified together with
PCATCH, to indicate that thread shall not be stopped upon receipt of
SIGSTOP until it reaches the kernel->usermode boundary.

Also change thread_single(SINGLE_NO_EXIT) to only stop threads at
the user boundary unconditionally.

Tested by:	pho
Reviewed by:	jhb
Approved by:	re (kensmith)
2009-07-14 22:52:46 +00:00
Konstantin Belousov
79799053a7 Move the repeated code to calculate the number of the threads in the
process that still need to be suspended or exited from thread_single
into the new function calc_remaining().

Tested by:	pho
Reviewed by:	jhb
Approved by:	re (kensmith)
2009-07-14 22:51:31 +00:00
Jeff Roberson
2e6b8de462 - Implement a new mechanism for resetting lock profiling. We now
guarantee that all cpus have acknowledged the cleared enable int by
   scheduling the resetting thread on each cpu in succession.  Since all
   lock profiling happens within a critical section this guarantees that
   all cpus have left lock profiling before we clear the datastructures.
 - Assert that the per-thread queue of locks lock profiling is aware of
   is clear on thread exit.  There were several cases where this was not
   true that slows lock profiling and leaks information.
 - Remove all objects from all lists before clearing any per-cpu
   information in reset.  Lock profiling objects can migrate between
   per-cpu caches and previously these migrated objects could be zero'd
   before they'd been removed

Discussed with:	attilio
Sponsored by:	Nokia
2009-03-15 06:41:47 +00:00
Pawel Jakub Dawidek
1ba4a712dd Update ZFS from version 6 to 13 and bring some FreeBSD-specific changes.
This bring huge amount of changes, I'll enumerate only user-visible changes:

- Delegated Administration

	Allows regular users to perform ZFS operations, like file system
	creation, snapshot creation, etc.

- L2ARC

	Level 2 cache for ZFS - allows to use additional disks for cache.
	Huge performance improvements mostly for random read of mostly
	static content.

- slog

	Allow to use additional disks for ZFS Intent Log to speed up
	operations like fsync(2).

- vfs.zfs.super_owner

	Allows regular users to perform privileged operations on files stored
	on ZFS file systems owned by him. Very careful with this one.

- chflags(2)

	Not all the flags are supported. This still needs work.

- ZFSBoot

	Support to boot off of ZFS pool. Not finished, AFAIK.

	Submitted by:	dfr

- Snapshot properties

- New failure modes

	Before if write requested failed, system paniced. Now one
	can select from one of three failure modes:
	- panic - panic on write error
	- wait - wait for disk to reappear
	- continue - serve read requests if possible, block write requests

- Refquota, refreservation properties

	Just quota and reservation properties, but don't count space consumed
	by children file systems, clones and snapshots.

- Sparse volumes

	ZVOLs that don't reserve space in the pool.

- External attributes

	Compatible with extattr(2).

- NFSv4-ACLs

	Not sure about the status, might not be complete yet.

	Submitted by:	trasz

- Creation-time properties

- Regression tests for zpool(8) command.

Obtained from:	OpenSolaris
2008-11-17 20:49:29 +00:00
David Xu
7b4a950a7d Revert rev 184216 and 184199, due to the way the thread_lock works,
it may cause a lockup.

Noticed by: peter, jhb
2008-11-05 03:01:23 +00:00
David Xu
3f9be10eb0 Actually, for signal and thread suspension, extra process spin lock is
unnecessary, the normal process lock and thread lock are enough. The
spin lock is still needed for process and thread exiting to mimic
single sched_lock.
2008-10-23 07:55:38 +00:00
David Xu
ffdc5a34ed Restore code wrongly removed in SVN revision 173004, it causes threaded
process to be stuck in execv().

Noticed by: delphij
2008-10-16 04:17:17 +00:00
David Xu
904c5ec4e3 Move per-thread userland debugging flags into seperated field,
this eliminates some problems of locking, e.g, a thread lock is needed
but can not be used at that time. Only the process lock is needed now
for new field.
2008-10-15 06:31:37 +00:00
John Baldwin
7847a9daec A suspended thread can, in fact, be swapped out. Thus,
thread_unsuspend_one() needs to optionally wakeup the swapper.  Since we
hold the thread lock for that entire function, however, we have to push
that requirement up into the caller.

Found by:	rwatson
2008-08-22 16:15:58 +00:00
Attilio Rao
3d06b4b330 Introduce some WITNESS improvements:
- Speedup the lock orderings lookup modifying the witness graph from a
  linked tree to a matrix. A table lookup caches the lock orderings in
  order to make a O(1) access for them. Any witness object has an unique
  index withing this lookup cache table.
- Reduce the lock contention on w_mtx acquiring it only when the LOR
  actually happens and not in a sane case. In order to do this don't totally
  flush lock lists (per-CPU spinlocks list and per-thread sleeplocks list)
  but check for ll_count anytime we need to have to verify allocations sanity.
- Introduce the function witness_thread_exit() in the witness namespace which
  should verify a thread doesn't hold any witness occurrence why exiting.
- Rename the sysctl debug.witness.graphs into debug.witness.fullgraph and
  add debug.witness.badstacks which prints out stacks for LOR revealed.
  This is implemented using the stack(9) support, which makes WITNESS to be
  dependent by the STACK option or by the DDB (including STACK) option.
- Fix style(9) for src/sys/kern/subr_witness.c

The hash table approach has been developed by Ilya Maykov on the behalf of
Isilon Systems which kindly released the patch.
Jeff Roberson, ported the patch to -CURRENT and fixed w_mtx contention, on the
behalf of Nokia.

Submitted by:	Ilya Maykov <ivmaykov at gmail dot com> (Isilon Systems), jeff
Sponsored by:	Nokia
2008-08-13 18:24:22 +00:00
John Baldwin
da7bbd2c08 If a thread that is swapped out is made runnable, then the setrunnable()
routine wakes up proc0 so that proc0 can swap the thread back in.
Historically, this has been done by waking up proc0 directly from
setrunnable() itself via a wakeup().  When waking up a sleeping thread
that was swapped out (the usual case when waking proc0 since only sleeping
threads are eligible to be swapped out), this resulted in a bit of
recursion (e.g. wakeup() -> setrunnable() -> wakeup()).

With sleep queues having separate locks in 6.x and later, this caused a
spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock).
An attempt was made to fix this in 7.0 by making the proc0 wakeup use
the ithread mechanism for doing the wakeup.  However, this required
grabbing proc0's thread lock to perform the wakeup.  If proc0 was asleep
elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated
into the same LOR since the thread lock would be some other sleepq lock.

Fix this by deferring the wakeup of the swapper until after the sleepq
lock held by the upper layer has been locked.  The setrunnable() routine
now returns a boolean value to indicate whether or not proc0 needs to be
woken up.  The end result is that consumers of the sleepq API such as
*sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup
proc0 if they get a non-zero return value from sleepq_abort(),
sleepq_broadcast(), or sleepq_signal().

Discussed with:	jeff
Glanced at by:	sam
Tested by:	Jurgen Weber  jurgen - ish com au
MFC after:	2 weeks
2008-08-05 20:02:31 +00:00
Jeff Roberson
8df78c41d6 - Make SCHED_STATS more generic by adding a wrapper to create the
variables and sysctl nodes.
 - In reset walk the children of kern_sched_stats and reset the counters
   via the oid_arg1 pointer.  This allows us to add arbitrary counters to
   the tree and still reset them properly.
 - Define a set of switch types to be passed with flags to mi_switch().
   These types are named SWT_*.  These types correspond to SCHED_STATS
   counters and are automatically handled in this way.
 - Make the new SWT_ types more specific than the older switch stats.
   There are now stats for idle switches, remote idle wakeups, remote
   preemption ithreads idling, etc.
 - Add switch statistics for ULE's pickcpu algorithm.  These stats include
   how much migration there is, how often affinity was successful, how
   often threads were migrated to the local cpu on wakeup, etc.

Sponsored by:	Nokia
2008-04-17 04:20:10 +00:00
Jeff Roberson
b7edba7704 - Add a new td flag TDF_NEEDSUSPCHK that is set whenever a thread needs
to enter thread_suspend_check().
 - Set TDF_ASTPENDING along with TDF_NEEDSUSPCHK so we can move the
   thread_suspend_check() to ast() rather than userret().
 - Check TDF_NEEDSUSPCHK in the sleepq_catch_signals() optimization so
   that we don't miss a suspend request.  If this is set use the
   expensive signal path.
 - Set NEEDSUSPCHK when creating a new thread in thr in case the
   creating thread is due to be suspended as well but has not yet.

Reviewed by:	davidxu (Authored original patch)
2008-03-21 08:23:25 +00:00
Jeff Roberson
79813875ab - There is no sense in calling sched_newthread() at thread_init() and
thread_fini().  The schedulers initialize themselves properly during
   sched_fork_thread() anyhow.  fini is only called when we're returning
   the memory to the allocator which surely doesn't care what state the
   memory is in.
2008-03-20 03:07:57 +00:00
Jeff Roberson
45aea8de6e - Restore the NULL check for td_cpuset. This can happen if a partially
constructed thread was torn down as is the case when we fail to allocate
   a kernel stack.
2008-03-19 06:20:21 +00:00
Jeff Roberson
374ae2a393 - Relax requirements for p_numthreads, p_threads, p_swtick, and p_nice from
requiring the per-process spinlock to only requiring the process lock.
 - Reflect these changes in the proc.h documentation and consumers throughout
   the kernel.  This is a substantial reduction in locking cost for these
   fields and was made possible by recent changes to threading support.
2008-03-19 06:19:01 +00:00
Jeff Roberson
6617724c5f Remove kernel support for M:N threading.
While the KSE project was quite successful in bringing threading to
FreeBSD, the M:N approach taken by the kse library was never developed
to its full potential.  Backwards compatibility will be provided via
libmap.conf for dynamically linked binaries and static binaries will
be broken.
2008-03-12 10:12:01 +00:00
Jeff Roberson
c5aa6b581d - Pass the priority argument from *sleep() into sleepq and down into
sched_sleep().  This removes extra thread_lock() acquisition and
   allows the scheduler to decide what to do with the static boost.
 - Change the priority arguments to cv_* to match sleepq/msleep/etc.
   where 0 means no priority change.  Catch -1 in cv_broadcastpri() and
   convert it to 0 for now.
 - Set a flag when sleeping in a way that is compatible with swapping
   since direct priority comparisons are meaningless now.
 - Add a sysctl to ule, kern.sched.static_boost, that defaults to on which
   controls the boost behavior.  Turning it off gives better performance
   in some workloads but needs more investigation.
 - While we're modifying sleepq, change signal and broadcast to both
   return with the lock held as the lock was held on enter.

Reviewed by:	jhb, peter
2008-03-12 06:31:06 +00:00
Jeff Roberson
bdb5bdf0b7 - KSE may free a thread that was never actually forked. This will leave
td_cpuset NULL.  Check for this condition before dereferencing the
   cpuset.

Reported by:	david@catwhisker.org, miwi@freebsd.org
Sponsored by:	Nokia
2008-03-12 05:01:14 +00:00
Jeff Roberson
d7f687fc9b Add cpuset, an api for thread to cpu binding and cpu resource grouping
and assignment.
 - Add a reference to a struct cpuset in each thread that is inherited from
   the thread that created it.
 - Release the reference when the thread is destroyed.
 - Add prototypes for syscalls and macros for manipulating cpusets in
   sys/cpuset.h
 - Add syscalls to create, get, and set new numbered cpusets:
   cpuset(), cpuset_{get,set}id()
 - Add syscalls for getting and setting affinity masks for cpusets or
   individual threads: cpuid_{get,set}affinity()
 - Add types for the 'level' and 'which' parameters for the cpuset.  This
   will permit expansion of the api to cover cpu masks for other objects
   identifiable with an id_t integer.  For example, IRQs and Jails may be
   coming soon.
 - The root set 0 contains all valid cpus.  All thread initially belong to
   cpuset 1.  This permits migrating all threads off of certain cpus to
   reserve them for special applications.

Sponsored by:	Nokia
Discussed with:	arch, rwatson, brooks, davidxu, deischen
Reviewed by:	antoine
2008-03-02 07:39:22 +00:00
Julian Elischer
6829a5c59e give thread0 the tid 100000 and bumpt the others to start at 100001
MFC after:	1 week
2007-12-22 04:56:48 +00:00