#
267654 |
|
19-Jun-2014 |
gjb |
Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.
Approved by: re (implicit) Sponsored by: The FreeBSD Foundation |
#
262192 |
|
18-Feb-2014 |
jhb |
MFC 261517,261520: Convert the license on files where I am the sole copyright holder to 2 clause BSD licenses.
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#
251147 |
|
30-May-2013 |
jhb |
MFC 246417,247116,248584: Rework the handling of stop signals in the NFS client. The changes in 195702, 195703, and 195821 prevented a thread from suspending while holding locks inside of NFS by forcing the thread to fail sleeps with EINTR or ERESTART but defer the thread suspension to the user boundary. However, this had the effect that stopping a process during an NFS request could abort the request and trigger EINTR errors that were visible to userland processes (previously the thread would have suspended and completed the request once it was resumed).
This change instead effectively masks stop signals while in the NFS client. It uses the existing TDF_SBDRY flag to effect this since SIGSTOP cannot be masked directly. Instead of setting PBDRY on individual sleeps, change the VFS_*() and VOP_*() methods to defer stop signals for filesystems which request this behavior via a new VFCF_SBDRY flag. Note that this has to be a VFC flag rather than a MNTK flag so that it works properly with VFS_MOUNT() when the mount is not yet fully constructed. For now, only the NFS clients set this new flag in VFS_SET().
A few other related changes: - Add an assertion to ensure that TDF_SBDRY doesn't leak to userland. - When a lookup request uses VOP_READLINK() to follow a symlink, mark the request as being on behalf of the thread performing the lookup (cnp_thread) rather than using a NULL thread pointer. This causes NFS to properly handle signals during this VOP on an interruptible mount. - 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.
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#
248085 |
|
09-Mar-2013 |
marius |
MFC: r227309 (partial)
Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs.
The SYSCTL_NODE macro defines a list that stores all child-elements of that node. If there's no SYSCTL_DECL macro anywhere else, there's no reason why it shouldn't be static.
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#
236344 |
|
30-May-2012 |
rstone |
MFC r235459 and r235471
r235459: 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
r235471: Fix typo in function name SDT_PROBE4 and unbreak 4BSD UP.
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#
225736 |
|
22-Sep-2011 |
kensmith |
Copy head to stable/9 as part of 9.0-RELEASE release cycle.
Approved by: re (implicit)
|
#
217916 |
|
26-Jan-2011 |
mdf |
Explicitly wire the user buffer rather than doing it implicitly in sbuf_new_for_sysctl(9). This allows using an sbuf with a SYSCTL_OUT drain for extremely large amounts of data where the caller knows that appropriate references are held, and sleeping is not an issue.
Inspired by: rwatson
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#
217410 |
|
14-Jan-2011 |
jhb |
Rework realtime priority support: - Move the realtime priority range up above kernel sleep priorities and just below interrupt thread priorities. - Contract the interrupt and kernel sleep priority ranges a bit so that the timesharing priority band can be increased. The new timeshare range is now slightly larger than the old realtime + timeshare ranges. - Change the ULE scheduler to no longer use realtime priorities for interactive threads. Instead, the larger timeshare range is now split into separate subranges for interactive and non-interactive ("batch") threads. The end result is that interactive threads and non-interactive threads still use the same priority ranges as before, but realtime threads now have a separate, dedicated priority range. - Do not modify the priority of non-timeshare threads in sched_sleep() or via cv_broadcastpri(). Realtime and idle priority threads will no longer have their priorities affected by sleeping in the kernel.
Reviewed by: jeff
|
#
212750 |
|
16-Sep-2010 |
mdf |
Re-add r212370 now that the LOR in powerpc64 has been resolved:
Add a drain function for struct sysctl_req, and use it for a variety of handlers, some of which had to do awkward things to get a large enough SBUF_FIXEDLEN buffer.
Note that some sysctl handlers were explicitly outputting a trailing NUL byte. This behaviour was preserved, though it should not be necessary.
Reviewed by: phk (original patch)
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#
212572 |
|
13-Sep-2010 |
mdf |
Revert r212370, as it causes a LOR on powerpc. powerpc does a few unexpected things in copyout(9) and so wiring the user buffer is not sufficient to perform a copyout(9) while holding a random mutex.
Requested by: nwhitehorn
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#
212370 |
|
09-Sep-2010 |
mdf |
Add a drain function for struct sysctl_req, and use it for a variety of handlers, some of which had to do awkward things to get a large enough FIXEDLEN buffer.
Note that some sysctl handlers were explicitly outputting a trailing NUL byte. This behaviour was preserved, though it should not be necessary.
Reviewed by: phk
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#
211534 |
|
20-Aug-2010 |
davidxu |
make sure thread lock is locked.
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#
211523 |
|
20-Aug-2010 |
davidxu |
If thread set a TDP_WAKEUP for itself, clears the flag and returns EINTR immediately, this is used for implementing reliable pthread cancellation.
|
#
209612 |
|
30-Jun-2010 |
jhb |
Update comment for tdsignal() -> tdsendsignal() rename. Forgot to include this in 209592.
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#
201879 |
|
08-Jan-2010 |
attilio |
Introduce the new kernel thread called "deadlock resolver". While the name is pretentious, a good explanation of its targets is reported in this 17 months old presentation e-mail: http://lists.freebsd.org/pipermail/freebsd-arch/2008-August/008452.html
In order to implement it, the sq_type in sleepqueues is mandatory and not only compiled along with INVARIANTS option. Additively, a new sleepqueue function, sleepq_type() is added, returning the type of the sleepqueue linked to a wchan. Three new sysctls are added in order to configure the thread: debug.deadlkres.slptime_threshold debug.deadlkres.blktime_threshold debug.deadlkres.sleepfreq
rappresenting the thresholds for sleep and block time that will lead to a deadlock matching (when exceeded), while the sleepfreq rappresents the number of seconds between 2 consecutive thread runnings. In order to enable the deadlock resolver thread recompile your kernel with the option DEADLKRES.
Reviewed by: jeff Tested by: pho, Giovanni Trematerra Sponsored by: Nokia Incorporated, Sandvine Incorporated MFC after: 2 weeks
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#
200447 |
|
12-Dec-2009 |
attilio |
In current code, threads performing an interruptible sleep (on both sxlock, via the sx_{s, x}lock_sig() interface, or plain lockmgr), will leave the waiters flag on forcing the owner to do a wakeup even when if the waiter queue is empty. That operation may lead to a deadlock in the case of doing a fake wakeup on the "preferred" (based on the wakeup algorithm) queue while the other queue has real waiters on it, because nobody is going to wakeup the 2nd queue waiters and they will sleep indefinitively.
A similar bug, is present, for lockmgr in the case the waiters are sleeping with LK_SLEEPFAIL on. In this case, even if the waiters queue is not empty, the waiters won't progress after being awake but they will just fail, still not taking care of the 2nd queue waiters (as instead the lock owned doing the wakeup would expect).
In order to fix this bug in a cheap way (without adding too much locking and complicating too much the semantic) add a sleepqueue interface which does report the actual number of waiters on a specified queue of a waitchannel (sleepq_sleepcnt()) and use it in order to determine if the exclusive waiters (or shared waiters) are actually present on the lockmgr (or sx) before to give them precedence in the wakeup algorithm. This fix alone, however doesn't solve the LK_SLEEPFAIL bug. In order to cope with it, add the tracking of how many exclusive LK_SLEEPFAIL waiters a lockmgr has and if all the waiters on the exclusive waiters queue are LK_SLEEPFAIL just wake both queues.
The sleepq_sleepcnt() introduction and ABI breakage require __FreeBSD_version bumping.
Reported by: avg, kib, pho Reviewed by: kib Tested by: pho
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#
195702 |
|
14-Jul-2009 |
kib |
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)
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#
185502 |
|
01-Dec-2008 |
davidxu |
Revision 184199 had not been fully reverted, add missing piece.
Reported by: phk
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#
184667 |
|
05-Nov-2008 |
davidxu |
Revert rev 184216 and 184199, due to the way the thread_lock works, it may cause a lockup.
Noticed by: peter, jhb
|
#
184653 |
|
04-Nov-2008 |
jhb |
Don't bother calling setrunnable() and clearing the sleeping flag in sleepq_resume_thread() if the thread isn't asleep.
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#
184216 |
|
23-Oct-2008 |
davidxu |
partly revert revision 184199, because TDF_NEEDSIGCHK is persitent when thread is in kernel mode, it can cause dead loop, now unlock process lock after acquired sleep queue lock and thread lock to avoid the problem. This means TDF_NEEDSIGCHK and TDF_NEEDSUSPCHK must be set with process lock and thread lock being hold at same time.
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#
184199 |
|
23-Oct-2008 |
davidxu |
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.
|
#
183054 |
|
15-Sep-2008 |
sam |
Make ddb command registration dynamic so modules can extend the command set (only so long as the module is present): o add db_command_register and db_command_unregister to add and remove commands, respectively o replace linker sets with SYSINIT's (and SYSUINIT's) that register commands o expose 3 list heads: db_cmd_table, db_show_table, and db_show_all_table for registering top-level commands, show operands, and show all operands, respectively
While here also: o sort command lists o add DB_ALIAS, DB_SHOW_ALIAS, and DB_SHOW_ALL_ALIAS to add aliases for existing commands o add "show all trace" as an alias for "show alltrace" o add "show all locks" as an alias for "show alllocks"
Submitted by: Guillaume Ballet <gballet@gmail.com> (original version) Reviewed by: jhb MFC after: 1 month
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#
182875 |
|
08-Sep-2008 |
jhb |
Close a race in sleepq_broadcast() where the sleepq could be reused after it had been assigned to the last sleeping thread. That thread might have started running on another CPU and have reused that sleep queue. Fix it by just walking the thread queue using TAILQ_FOREACH_SAFE() rather than a while loop.
PR: amd64/124200 Discovered by: tegge Tested by: benjsc MFC after: 1 week
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#
181334 |
|
05-Aug-2008 |
jhb |
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
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#
180930 |
|
28-Jul-2008 |
jhb |
Really fix this.
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#
180927 |
|
28-Jul-2008 |
pjd |
Properly check if td_name is empty and if it is, print process name, instead of empty thread name.
Reviewed by: jhb
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#
178272 |
|
17-Apr-2008 |
jeff |
- 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
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#
177860 |
|
02-Apr-2008 |
jeff |
- Convert two timeout users to the new callout_reset_curcpu() api.
Sponsored by: Nokia
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#
177471 |
|
21-Mar-2008 |
jeff |
- 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)
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#
177375 |
|
19-Mar-2008 |
jeff |
- At the top of sleepq_catch_signals() lock the thread and check TDF_NEEDSIGCHK before doing the very expensive cursig() and related locking. NEEDSIGCHK is updated whenever our signal mask change or when a signal is delivered and should be sufficient to avoid the more expensive tests. This eliminates another source of PROC_LOCK contention in multithreaded programs.
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#
177372 |
|
19-Mar-2008 |
jeff |
- Add a facility similar to LOCK_PROFILING under SLEEPQUEUE_PROFILING. Keep a simple (wmesg, count) tuple in a hash to keep track of how many times we sleep at each wait message. We hash on message and not channel. No line number information is given as typically wait messages are not used in more than one place. Identical strings defined at different addresses will show up with seperate counters. - Use debug.sleepq.enable to enable, .reset to reset, and .stats dumps stats. - Do an unsynchronized check in sleepq_switch() prior to switching before calling sleepq_profile() which uses a global lock to synchronize the hash. Only sleeps which actually cause a context switch are counted.
|
#
177132 |
|
12-Mar-2008 |
jeff |
PR 117603 - Close a sleepqueue signal race by interlocking with the per-process spinlock. This was mistakenly omitted from the thread_lock patch and has been a race since.
MFC After: 1 week PR: bin/117603 Reported by: Danny Braniss <danny@cs.huji.ac.il>
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#
177091 |
|
12-Mar-2008 |
jeff |
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.
|
#
177085 |
|
12-Mar-2008 |
jeff |
- 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
|
#
176258 |
|
13-Feb-2008 |
jhb |
Mark sleepqueue chain spin mutexes are recursable since the sleepq code now recurses on them in sleepq_broadcast() and sleepq_signal() when resuming threads that are fully asleep.
MFC after: 1 week
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#
176078 |
|
07-Feb-2008 |
jeff |
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts.
Sponsored by: Nokia
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#
175664 |
|
25-Jan-2008 |
jhb |
Fix a bug where a thread that hit the race where the sleep timeout fires while the thread does not hold the thread lock would stop blocking for subsequent interruptible sleeps and would always immediately fail the sleep with EWOULDBLOCK instead (even sleeps that didn't have a timeout).
Some background: - KSE has a facility for allowing one thread to interrupt another thread. During this process, the target thread aborts any interruptible sleeps much as if the target thread had a pending signal. Once the target thread acknowledges the interrupt, normal sleep handling resumes. KSE manages this via the TDF_INTERRUPTED flag. Specifically, it sets the flag when it sends an interrupt to another thread and clears it when the interrupt is acknowledged. (Note that this is purely a software interrupt sort of thing and has no relation to hardware interrupts or kernel interrupt threads.) - The old code for handling the sleep timeout race handled the race by setting the TDF_INTERRUPT flag and faking a KSE-style thread interrupt to the thread in the process of going to sleep. It probably should have just checked the TDF_TIMEOUT flag in sleepq_catch_signals() instead. - The bug was that the sleepq code would set TDF_INTERRUPT but it was never cleared. The sleepq code couldn't safely clear it in case there actually was a real KSE thread interrupt pending for the target thread (in fact, the sleepq timeout actually stomped on said pending interrupt). Thus, any future interruptible sleeps (*sleep(.. PCATCH ..) or cv_*wait_sig()) would see the TDF_INTERRUPT flag set and immediately fail with EWOULDBLOCK. The flag could be cleared if the thread belonged to a KSE process and another thread posted an interrupt to the original thread. However, in the more common case of a non-KSE process, the thread would pretty much stop sleeping. - Fix the bug by just setting TDF_TIMEOUT in the sleepq timeout code and not messing with TDF_INTERRUPT and td_intrval. With yesterday's fix to fix sleepq_switch() to check TDF_TIMEOUT, this is now sufficient.
MFC after: 3 days
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#
175654 |
|
25-Jan-2008 |
jhb |
Fix a race in the sleepqueue timeout code that resulted in sleeps not being properly cancelled by a timeout. In general there is a race between a the sleepq timeout handler firing while the thread is still in the process of going to sleep. In 6.x with sched_lock, the race was largely protected by sched_lock. The only place it was "exposed" and had to be handled was while checking for any pending signals in sleepq_catch_signals().
With the thread lock changes, the thread lock is dropped in between sleepq_add() and sleepq_*wait*() opening up a new window for this race. Thus, if the timeout fired while the sleeping thread was in between sleepq_add() and sleepq_*wait*(), the thread would be marked as timed out, but the thread would not be dequeued and sleepq_switch() would still block the thread until it was awakened via some other means. In the case of pause(9) where there is no other wakeup, the thread would never be awakened.
Fix this by teaching sleepq_switch() to check if the thread has had its sleep canceled before blocking by checking the TDF_TIMEOUT flag and aborting the sleep and dequeueing the thread if it is set.
MFC after: 3 days Reported by: dwhite, peter
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#
173601 |
|
14-Nov-2007 |
julian |
A bunch more files that should probably print out a thread name instead of a process name.
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#
173600 |
|
14-Nov-2007 |
julian |
generally we are interested in what thread did something as opposed to what process. Since threads by default have teh name of the process unless over-written with more useful information, just print the thread name instead.
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#
172155 |
|
13-Sep-2007 |
attilio |
subr_sleepqueue.c presents a thread lock missing which leads to dangerous races for some struct thread members. More specifically, this bug seems responsible for some memory dumping problems people were experiencing.
Fix this adding correct thread locking.
Tested by: rwatson Submitted by: tegge Approved by: jeff Approved by: re
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#
170640 |
|
12-Jun-2007 |
jeff |
- Include opt_sched.h for SCHED_STATS.
|
#
170294 |
|
04-Jun-2007 |
jeff |
Commit 2/14 of sched_lock decomposition. - Adapt sleepqueues to the new thread_lock() mechanism. - Delay assigning the sleep queue spinlock as the thread lock until after we've checked for signals. It is illegal for a thread to return in mi_switch() with any lock assigned to td_lock other than the scheduler locks. - Change sleepq_catch_signals() to do the switch if necessary to simplify the callers. - Simplify timeout handling now that locking a sleeping thread has the side-effect of locking the sleepqueue. Some previous races are no longer possible.
Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
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#
169666 |
|
18-May-2007 |
jeff |
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now.
Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
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#
165292 |
|
16-Dec-2006 |
kmacy |
Cleaner fix for handling declaration of loop variable under INVARIANTS - in trying to avoid nested brackets and #ifdef INVARIANTS around i at the top, I broke booting for INVARIANTS all together :-( - the cleanest fix is to simply assign to sq twice if INVARIANTS is enabled - tested both with and without INVARIANTS :-/
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#
165291 |
|
16-Dec-2006 |
ache |
Don't intermix assignments and variable declarations in prev. commit
|
#
165290 |
|
16-Dec-2006 |
ache |
Fix NULL pointer reference for INVARIANTS case
Submitted by: Yuriy Tsibizov <Yuriy.Tsibizov@gfk.ru>
|
#
165275 |
|
16-Dec-2006 |
kmacy |
correct name of number of sleep queues
|
#
165272 |
|
16-Dec-2006 |
kmacy |
Add second sleep queue so that sx and lockmgr can have separate sleep queues for shared and exclusive acquisitions
Submitted by: Attilio Rao Approved by: jhb
|
#
164325 |
|
15-Nov-2006 |
pjd |
Change sleepq_add(9) argument from 'struct mtx *' to 'struct lock_object *', which allows to use it with different kinds of locks. For example it allows to implement Solaris conditions variables which will be used in ZFS port on top of sx(9) locks.
Reviewed by: jhb
|
#
157952 |
|
21-Apr-2006 |
jhb |
Print td_name instead of p_comm if td_name is non-empty for 'show turnstile' and 'show sleepq'.
|
#
157823 |
|
17-Apr-2006 |
jhb |
Add a 'show sleepqueue' alias for 'show sleepq' in DDB.
|
#
157743 |
|
13-Apr-2006 |
davidxu |
Clear TDF_SINTR in sleepq_resume_thread, also sleepq_catch_signal does not need to clear it now, this should fix panic when msleep is recursivly called. Patch is slightly adjusted after review.
Reviewed by: jhb Tested by: Csaba Henk, csaba-ml at creo.hu MFC after: 3 days
|
#
155936 |
|
23-Feb-2006 |
davidxu |
Move comments to more accurate place.
|
#
155932 |
|
22-Feb-2006 |
davidxu |
Fix a sleep queue race for KSE thread.
Reviewed by: jhb
|
#
155741 |
|
15-Feb-2006 |
davidxu |
Fix a long standing race between sleep queue and thread suspension code. When a thread A is going to sleep, it calls sleepq_catch_signals() to detect any pending signals or thread suspension request, if nothing happens, it returns without holding process lock or scheduler lock, this opens a race window which allows thread B to come in and do process suspension work, however since A is still at running state, thread B can do nothing to A, thread A continues, and puts itself into actually sleeping state, but B has never seen it, and it sits there forever until B is woken up by other threads sometimes later(this can be very long delay or never happen). Fix this bug by forcing sleepq_catch_signals to return with scheduler lock held. Fix sleepq_abort() by passing it an interrupted code, previously, it worked as wakeup_one(), and the interruption can not be identified correctly by sleep queue code when the sleeping thread is resumed. Let thread_suspend_check() returns EINTR or ERESTART, so sleep queue no longer has to use SIGSTOP as a hack to build a return value.
Reviewed by: jhb MFC after: 1 week
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#
154944 |
|
27-Jan-2006 |
imp |
lock unused when INVARIANTS not defined, so don't declare it then
|
#
154936 |
|
27-Jan-2006 |
jhb |
Add a new ddb command 'show sleepq'. It takes a wait channel as an argument and looks for a sleep queue associated with that wait channel. If it finds one it will display information such as the list of threads sleeping on that queue. If it can't find a sleep queue for that wait channel, then it will see if that address matches any of the active sleep queues. If so, it will display information about the sleepq at the specified address.
|
#
152221 |
|
09-Nov-2005 |
imp |
Clarify panic message, I parsed the old one 'trying to sleep while sleeping'
|
#
151897 |
|
31-Oct-2005 |
rwatson |
Normalize a significant number of kernel malloc type names:
- Prefer '_' to ' ', as it results in more easily parsed results in memory monitoring tools such as vmstat.
- Remove punctuation that is incompatible with using memory type names as file names, such as '/' characters.
- Disambiguate some collisions by adding subsystem prefixes to some memory types.
- Generally prefer lower case to upper case.
- If the same type is defined in multiple architecture directories, attempt to use the same name in additional cases.
Not all instances were caught in this change, so more work is required to finish this conversion. Similar changes are required for UMA zone names.
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150177 |
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15-Sep-2005 |
jhb |
- Add a new simple facility for marking the current thread as being in a state where sleeping on a sleep queue is not allowed. The facility doesn't support recursion but uses a simple private per-thread flag (TDP_NOSLEEPING). The sleepq_add() function will panic if the flag is set and INVARIANTS is enabled. - Use this new facility to replace the g_xup and g_xdown mutexes that were (ab)used to achieve similar behavior. - Disallow sleeping in interrupt threads when invoking interrupt handlers.
MFC after: 1 week Reviewed by: phk
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146687 |
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27-May-2005 |
davidxu |
Remove thread_upcall_check, it was used to avoid race bug in earlier day's sleep queue code, today the bug no longer exists. please see 04/25/2004 freebsd-threads@ mailing list archive.
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145056 |
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14-Apr-2005 |
jhb |
Close a race between sleepq_broadcast() and sleepq_catch_signals(). Specifically, sleepq_broadcast() uses td_slpq for its private pending queue of threads that it is going to wake up after it takes them off the sleep queue. The problem is that if one of the threads is actually not asleep yet, then we can end up with td_slpq being corrupted and/or the thread being made runnable at the wrong time resulting in the td_sleepqueue == NULL assertion failures occasionally reported under heavy load.
The fix is to stop being so fancy and ditch the whole pending queue bit. Instead, sleepq_remove_thread() and sleepq_resume_thread() were merged into one function that requires the caller to hold sched_lock. This fixes several places that unlocked sched_lock only to call a function that then locked sched_lock, so even though sched_lock is now held slightly longer, removing the extra lock acquires (1 pair instead of 3 in some cases) probably makes it an overall win if you don't include the fact that it closes a race. This is definitely a 5.4 candidate.
PR: kern/79693 Submitted by: Steven Sears stevenjsears at yahoo dot com MFC after: 4 days
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141616 |
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10-Feb-2005 |
phk |
Make a bunch of malloc types static.
Found by: src/tools/tools/kernxref
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139804 |
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06-Jan-2005 |
imp |
/* -> /*- for copyright notices, minor format tweaks as necessary
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137277 |
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05-Nov-2004 |
jhb |
- Store threads on sleep queues in FIFO order rather than sorted by priority. The sleep queues don't get updated when the priority of threads changes, so sleepq_signal() might not always wakeup the highest priority thread. Updating the queues when thread priorities change cannot be easily done due to lock orders, so instead we do an O(n) walk of the queue for a sleepq_signal() operation instead of O(1). On the other hand, adding a thread to a sleep queue now goes from O(n) to O(1) so it ends up as an even tradeoff. The correctness here with regards to priorities is actually fairly important. msleep() gives interactive threads their priority "boost" after they are placed on the queue, but before this fix that "boost" wasn't used to determine the highest priority thread that sleepq_signal() awoke. - Fix up some comments.
Inspired by: ups, bde
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136445 |
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12-Oct-2004 |
jhb |
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches.
MFC after: 1 month
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136439 |
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12-Oct-2004 |
ups |
Directly modifying the priority of a thread that may be on the runqueue can break the sorting order of the ksegp run queue.
Tested by: pho Reviewed by: jhb, julian Approved by: sam (mentor) MFC: ASAP
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134013 |
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19-Aug-2004 |
jhb |
Now that the return value semantics of cv's for multithreaded processes have been unified with that of msleep(9), further refine the sleepq interface and consolidate some duplicated code: - Move the pre-sleep checks for theaded processes into a thread_sleep_check() function in kern_thread.c. - Move all handling of TDF_SINTR to be internal to subr_sleepqueue.c. Specifically, if a thread is awakened by something other than a signal while checking for signals before going to sleep, clear TDF_SINTR in sleepq_catch_signals(). This removes a sched_lock lock/unlock combo in that edge case during an interruptible sleep. Also, fix sleepq_check_signals() to properly handle the condition if TDF_SINTR is clear rather than requiring the callers of the sleepq API to notice this edge case and call a non-_sig variant of sleepq_wait(). - Clarify the flags arguments to sleepq_add(), sleepq_signal() and sleepq_broadcast() by creating an explicit submask for sleepq types. Also, add an explicit SLEEPQ_MSLEEP type rather than a magic number of 0. Also, add a SLEEPQ_INTERRUPTIBLE flag for use with sleepq_add() and move the setting of TDF_SINTR to sleepq_add() if this flag is set rather than sleepq_catch_signals(). Note that it is the caller's responsibility to ensure that sleepq_catch_signals() is called if and only if this flag is passed to the preceeding sleepq_add(). Note that this also removes a sched_lock lock/unlock pair from sleepq_catch_signals(). It also ensures that for an interruptible sleep, TDF_SINTR is always set when TD_ON_SLEEPQ() is true.
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131473 |
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02-Jul-2004 |
jhb |
- Change mi_switch() and sched_switch() to accept an optional thread to switch to. If a non-NULL thread pointer is passed in, then the CPU will switch to that thread directly rather than calling choosethread() to pick a thread to choose to. - Make sched_switch() aware of idle threads and know to do TD_SET_CAN_RUN() instead of sticking them on the run queue rather than requiring all callers of mi_switch() to know to do this if they can be called from an idlethread. - Move constants for arguments to mi_switch() and thread_single() out of the middle of the function prototypes and up above into their own section.
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131259 |
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29-Jun-2004 |
jhb |
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
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131249 |
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28-Jun-2004 |
jhb |
Remove the signal_caught argument from sleepq_timedwait() as it was effectively always zero.
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129241 |
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14-May-2004 |
bde |
Fixed some common printf format errors. Don't assume that "struct foo *" is "void *" (it isn't) or that the default promotion of pid_t is int. Instead, assume that casting "struct foo *" to "void *" and printing the result with %p is useful, and that all pid_t's are representable as longs.
Fixed some minor style bugs (mainly spelling errors in comments).
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129188 |
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13-May-2004 |
jhb |
Split sleepq_wakeup_thread() into two functions. sleepq_remove_thread() removes a specific thread from a sleep queue. sleepq_resume_thread() resumes scheduling of a thread that has been previously removed from a sleep queue. - sleepq_catch_signals() just removes a thread from the queue it was just added to when a pending signal is found. - sleepq_signal() and sleepq_broadcast() remove threads from a queue, drop the queue lock, and then resume all the previously removed threads. This doesn't completely fix the sched_lock <-> sleepq chain LOR, but it makes it a little better as we no longer call setrunnble() with a sleep queue lock held meaning if setrunnable() tries to wakeup the swapper we don't try to lock two sleep queue chains at the same time.
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128721 |
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28-Apr-2004 |
deischen |
Keep track of threads waiting in kse_release() to avoid a race condition where kse_wakeup() doesn't yet see them in (interruptible) sleep queues. Also add an upcall check to sleepqueue_catch_signals() suggested by jhb.
This commit should fix recent mysql hangs.
Reviewed by: jhb, davidxu Mysql'd by: Robin P. Blanchard <robin.blanchard at gactr uga edu>
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127085 |
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16-Mar-2004 |
jhb |
Remove a bogus assertion and readd it in a more correct location. A thread might be enqueued on a sleep queue but not be asleep when the timeout fires if it is blocked on a lock trying to check for pending signals before going to sleep. In the case of fixing up the TDF_TIMEOUT race, however, the thread must be marked asleep.
Reported by: kan (the bogus one)
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126885 |
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12-Mar-2004 |
jhb |
- Remove old sleep queues. - Remove sleepqueue argument from sleepq_set_timeout() since it is not used.
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126488 |
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02-Mar-2004 |
jhb |
Always assert that the passed in lock is the same as the saved lock in the sleep queue now that the one abnormal case has been fixed.
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126324 |
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27-Feb-2004 |
jhb |
Add an implementation of a generic sleep queue abstraction that is used to queue threads sleeping on a wait channel similar to how turnstiles are used to queue threads waiting for a lock. This subsystem will be used as the backend for sleep/wakeup and condition variables initially. Eventually it will also be used to replace the ithread-specific iwait thread inhibitor.
Sleep queues are also not locked by sched_lock, so this splits sched_lock up a bit further increasing concurrency within the scheduler. Sleep queues also natively support timeouts on sleeps and interruptible sleeps allowing for the reduction of a lot of duplicated code between the sleep/wakeup and condition variable implementations. For more details on the sleep queue implementation, check the comments in sys/sleepqueue.h and kern/subr_sleepqueue.c.
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