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* MFC r285706,r303562,r303563,r303584,r303643,r303652,r303655,r303707:mjg2016-12-311-10/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (by markj) Don't increment the spin count until after the first attempt to acquire a rwlock read lock. Otherwise the lockstat:::rw-spin probe will fire spuriously. == rwlock: s/READER/WRITER/ in wlock lockstat annotation == sx: increment spin_cnt before cpu_spinwait in xlock The change is a no-op only done for consistency with the rest of the file. == locks: change sleep_cnt and spin_cnt types to u_int Both variables are uint64_t, but they only count spins or sleeps. All reasonable values which we can get here comfortably hit in 32-bit range. == Implement trivial backoff for locking primitives. All current spinning loops retry an atomic op the first chance they get, which leads to performance degradation under load. One classic solution to the problem consists of delaying the test to an extent. This implementation has a trivial linear increment and a random factor for each attempt. For simplicity, this first thouch implementation only modifies spinning loops where the lock owner is running. spin mutexes and thread lock were not modified. Current parameters are autotuned on boot based on mp_cpus. Autotune factors are very conservative and are subject to change later. == locks: fix up ifdef guards introduced in r303643 Both sx and rwlocks had copy-pasted ADAPTIVE_MUTEXES instead of the correct define. == locks: fix compilation for KDTRACE_HOOKS && !ADAPTIVE_* case == locks: fix sx compilation on mips after r303643 The kernel.h header is required for the SYSINIT macro, which apparently was present on amd64 by accident.
* MFC r301157:mjg2016-12-311-4/+9
| | | | | | | | | | Microoptimize locking primitives by avoiding unnecessary atomic ops. Inline version of primitives do an atomic op and if it fails they fallback to actual primitives, which immediately retry the atomic op. The obvious optimisation is to check if the lock is free and only then proceed to do an atomic op.
* MFC r306346vangyzen2016-10-191-1/+1
| | | | | | | | Make no assertions about mutex state when the scheduler is stopped. This changes the assert path to match the lock and unlock paths. Sponsored by: Dell EMC
* MFC r303211:kib2016-07-301-0/+28
| | | | Implement mtx_trylock_spin(9).
* MFC r302346:markj2016-07-161-1/+8
| | | | Ensure that spinlock sections are balanced even after a panic.
* MFC r285663, r285664, r285667:markj2015-07-211-9/+12
| | | | | | | | | Ensure that locstat_nsecs() has no effect when lockstat probes are not enabled or when the profiled lock carries the LO_NOPROFILE flag. PR: 201642, 201517 Approved by: re (gjb) Tested by: Jason Unovitch
* MFC r284297: several lockstat improvementsavg2015-07-011-9/+25
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* MFC 272315 272757 274091 274902sbruno2015-02-131-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | for real this time r272315 Explicitly return None for negative event indices. Prior to this, eventat(-1) would return the next-to-last event causing the back button to cycle back to the end of an event source instead of stopping at the start. r272757 Add schedgraph traces for callout handlers. Specifically, a callwheel logs a running event each time it executes a callout function. The event includes the function pointer, argument, and whether or not it was run from hardware interrupt context. The callwheel is marked idle when each handler completes. This effectively logs the duration of each callout routine in the graph. r274091 Bind Ctrl-Q as a global hotkey to exit. Bind Ctrl-W as a hotkey to close dialogs. r274902 Add a new thread state "spinning" to schedgraph and add tracepoints at the start and stop of spinning waits in lock primitives. Reviewed by: jhb
* Revert r278650. Definite layer 8 bug.sbruno2015-02-131-11/+0
| | | | Submitted by: dhw and Thomas Mueller <tmueller@sysgo.com>
* MFC 272315 272757 274091 274902sbruno2015-02-131-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | r272315 Explicitly return None for negative event indices. Prior to this, eventat(-1) would return the next-to-last event causing the back button to cycle back to the end of an event source instead of stopping at the start. r272757 Add schedgraph traces for callout handlers. Specifically, a callwheel logs a running event each time it executes a callout function. The event includes the function pointer, argument, and whether or not it was run from hardware interrupt context. The callwheel is marked idle when each handler completes. This effectively logs the duration of each callout routine in the graph. r274091 Bind Ctrl-Q as a global hotkey to exit. Bind Ctrl-W as a hotkey to close dialogs. r274902 Add a new thread state "spinning" to schedgraph and add tracepoints at the start and stop of spinning waits in lock primitives. Reviewed by: jhb
* Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. Withdavide2013-09-201-8/+8
| | | | | | | | | | | | | | | current lock classes KPI it was really difficult because there was no way to pass an rmtracker object to the lock/unlock routines. In order to accomplish the task, modify the aforementioned functions so that they can return (or pass as argument) an uinptr_t, which is in the rm case used to hold a pointer to struct rm_priotracker for current thread. As an added bonus, this fixes rm_sleep() in the rm shared case, which right now can communicate priotracker structure between lc_unlock()/lc_lock(). Suggested by: jhb Reviewed by: jhb Approved by: re (delphij)
* Give mutex(9) the ability to recurse on a per-instance basis.attilio2013-08-091-6/+14
| | | | | | | | | | Now the MTX_RECURSE flag can be passed to the mtx_*_flag() calls. This helps in cases we want to narrow down to specific calls the possibility to recurse for some locks. Sponsored by: EMC / Isilon storage division Reviewed by: jeff, alc Tested by: pho
* Fix r253823. Some WIP patches snuck in.scottl2013-07-301-14/+6
| | | | Submitted by: zont
* Create a knob, kern.ipc.sfreadahead, that allows one to tune the amount ofscottl2013-07-301-6/+14
| | | | | | | readahead that sendfile() will do. Default remains the same. Obtained from: Netflix MFC after: 3 days
* A few mostly cosmetic nits to aid in debugging:jhb2013-06-251-3/+3
| | | | | | | | - Call lock_init() first before setting any lock_object fields in lock init routines. This way if the machine panics due to a duplicate init the lock's original state is preserved. - Somewhat similarly, don't decrement td_locks and td_slocks until after an unlock operation has completed successfully.
* Fixup r240424: On entering KDB backends, the hijacked thread to runattilio2012-12-221-2/+2
| | | | | | | | | | | | | interrupt context can still be idlethread. At that point, without the panic condition, it can still happen that idlethread then will try to acquire some locks to carry on some operations. Skip the idlethread check on block/sleep lock operations when KDB is active. Reported by: jh Tested by: jh MFC after: 1 week
* Give mtx(9) the ability to crunch different type of structures, with theattilio2012-10-311-17/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | | only constraint that they have a lock cookie named mtx_lock. This name, then, becames reserved from the struct that wants to use the mtx(9) KPI and other locking primitives cannot reuse it for their members. Namely such structs are the current struct mtx and the new struct mtx_padalign. The new structure will define an object which is the same as the same layout of a struct mtx but will be allocated in areas aligned to the cache line size and will be as big as a cache line. This is supposed to give higher performance for highly contented mutexes both spin or sleep (because of the adaptive spinning), where the cache line contention results in too much traffic on the system bus. The struct mtx_padalign can be used in a completely transparent way with the mtx(9) KPI. At the moment, a possibility to MFC the patch should be carefully evaluated because this patch breaks the low level KPI (not its representation though). Discussed with: jhb Reviewed by: jeff, andre Reviewed by: mdf (earlier version) Tested by: jimharris
* Remove all the checks on curthread != NULL with the exception of some MDattilio2012-09-131-5/+0
| | | | | | | | | | | 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
* Improve check coverage about idle threads.attilio2012-09-121-0/+6
| | | | | | | | | | | | Idle threads are not allowed to acquire any lock but spinlocks. Deny any attempt to do so by panicing at the locking operation when INVARIANTS is on. Then, remove the check on blocking on a turnstile. The check in sleepqueues is left because they are not allowed to use tsleep() either which could happen still. Reviewed by: bde, jhb, kib MFC after: 1 week
* Add software PMC support.fabient2012-03-281-0/+15
| | | | | | | | | | | | | New kernel events can be added at various location for sampling or counting. This will for example allow easy system profiling whatever the processor is with known tools like pmcstat(8). Simultaneous usage of software PMC and hardware PMC is possible, for example looking at the lock acquire failure, page fault while sampling on instructions. Sponsored by: NETASQ MFC after: 1 month
* panic: add a switch and infrastructure for stopping other CPUs in SMP caseavg2011-12-111-0/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Historical behavior of letting other CPUs merily go on is a default for time being. The new behavior can be switched on via kern.stop_scheduler_on_panic tunable and sysctl. Stopping of the CPUs has (at least) the following benefits: - more of the system state at panic time is preserved intact - threads and interrupts do not interfere with dumping of the system state Only one thread runs uninterrupted after panic if stop_scheduler_on_panic is set. That thread might call code that is also used in normal context and that code might use locks to prevent concurrent execution of certain parts. Those locks might be held by the stopped threads and would never be released. To work around this issue, it was decided that instead of explicit checks for panic context, we would rather put those checks inside the locking primitives. This change has substantial portions written and re-written by attilio and kib at various times. Other changes are heavily based on the ideas and patches submitted by jhb and mdf. bde has provided many insights into the details and history of the current code. The new behavior may cause problems for systems that use a USB keyboard for interfacing with system console. This is because of some unusual locking patterns in the ukbd code which have to be used because on one hand ukbd is below syscons, but on the other hand it has to interface with other usb code that uses regular mutexes/Giant for its concurrency protection. Dumping to USB-connected disks may also be affected. PR: amd64/139614 (at least) In cooperation with: attilio, jhb, kib, mdf Discussed with: arch@, bde Tested by: Eugene Grosbein <eugen@grosbein.net>, gnn, Steven Hartland <killing@multiplay.co.uk>, glebius, Andrew Boyer <aboyer@averesystems.com> (various versions of the patch) MFC after: 3 months (or never)
* Introduce macro stubs in the mutex implementation that will be alwaysattilio2011-11-201-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | defined and will allow consumers, willing to provide options, file and line to locking requests, to not worry about options redefining the interfaces. This is typically useful when there is the need to build another locking interface on top of the mutex one. The introduced functions that consumers can use are: - mtx_lock_flags_ - mtx_unlock_flags_ - mtx_lock_spin_flags_ - mtx_unlock_spin_flags_ - mtx_assert_ - thread_lock_flags_ Spare notes: - Likely we can get rid of all the 'INVARIANTS' specification in the ppbus code by using the same macro as done in this patch (but this is left to the ppbus maintainer) - all the other locking interfaces may require a similar cleanup, where the most notable case is sx which will allow a further cleanup of vm_map locking facilities - The patch should be fully compatible with older branches, thus a MFC is previewed (infact it uses all the underlying mechanisms already present). Comments review by: eadler, Ben Kaduk Discussed with: kib, jhb MFC after: 1 month
* Constify arguments for locking KPIs where possible.pjd2011-11-161-11/+12
| | | | | | | This enables locking consumers to pass their own structures around as const and be able to assert locks embedded into those structures. Reviewed by: ed, kib, jhb
* - Remove <machine/mutex.h>. Most of the headers were empty, and thejhb2010-11-091-11/+11
| | | | | | | | | | | | contents of the ones that were not empty were stale and unused. - Now that <machine/mutex.h> no longer exists, there is no need to allow it to override various helper macros in <sys/mutex.h>. - Rename various helper macros for low-level operations on mutexes to live in the _mtx_* or __mtx_* namespaces. While here, change the names to more closely match the real API functions they are backing. - Drop support for including <sys/mutex.h> in assembly source files. Suggested by: bde (1, 2)
* Right now, WITNESS just blindly pipes all the output to theattilio2010-05-111-1/+1
| | | | | | | | | | | | | (TOCONS | TOLOG) mask even when called from DDB points. That breaks several output, where the most notable is textdump output. Fix this by having configurable callbacks passed to witness_list_locks() and witness_display_spinlock() for printing out datas. Reported by: several broken textdump outputs Tested by: Giovanni Trematerra <giovanni dot trematerra at gmail dot com> MFC after: 7 days X-MFC: r207922
* - Fix a race in sched_switch() of sched_4bsd.attilio2010-01-231-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | In the case of the thread being on a sleepqueue or a turnstile, the sched_lock was acquired (without the aid of the td_lock interface) and the td_lock was dropped. This was going to break locking rules on other threads willing to access to the thread (via the td_lock interface) and modify his flags (allowed as long as the container lock was different by the one used in sched_switch). In order to prevent this situation, while sched_lock is acquired there the td_lock gets blocked. [0] - Merge the ULE's internal function thread_block_switch() into the global thread_lock_block() and make the former semantic as the default for thread_lock_block(). This means that thread_lock_block() will not disable interrupts when called (and consequently thread_unlock_block() will not re-enabled them when called). This should be done manually when necessary. Note, however, that ULE's thread_unblock_switch() is not reaped because it does reflect a difference in semantic due in ULE (the td_lock may not be necessarilly still blocked_lock when calling this). While asymmetric, it does describe a remarkable difference in semantic that is good to keep in mind. [0] Reported by: Kohji Okuno <okuno dot kohji at jp dot panasonic dot com> Tested by: Giovanni Trematerra <giovanni dot trematerra at gmail dot com> MFC: 2 weeks
* Revert previous commit and add myself to the list of people who shouldphk2009-09-081-6/+5
| | | | know better than to commit with a cat in the area.
* Add necessary include.phk2009-09-081-5/+6
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* * Change the scope of the ASSERT_ATOMIC_LOAD() from a generic check toattilio2009-08-171-2/+3
| | | | | | | | | | | | | | | a pointer-fetching specific operation check. Consequently, rename the operation ASSERT_ATOMIC_LOAD_PTR(). * Fix the implementation of ASSERT_ATOMIC_LOAD_PTR() by checking directly alignment on the word boundry, for all the given specific architectures. That's a bit too strict for some common case, but it assures safety. * Add a comment explaining the scope of the macro * Add a new stub in the lockmgr specific implementation Tested by: marcel (initial version), marius Reviewed by: rwatson, jhb (comment specific review) Approved by: re (kib)
* Add a new macro to test that a variable could be loaded atomically.bz2009-08-141-0/+2
| | | | | | | | | | | | | | | | | | | Check that the given variable is at most uintptr_t in size and that it is aligned. Note: ASSERT_ATOMIC_LOAD() uses ALIGN() to check for adequate alignment -- however, the function of ALIGN() is to guarantee alignment, and therefore may lead to stronger alignment enforcement than necessary for types that are smaller than sizeof(uintptr_t). Add checks to mtx, rw and sx locks init functions to detect possible breakage. This was used during debugging of the problem fixed with r196118 where a pointer was on an un-aligned address in the dpcpu area. In collaboration with: rwatson Reviewed by: rwatson Approved by: re (kib)
* Remove extra cpu_spinwait() invocations. This should really only be usedjhb2009-05-291-3/+0
| | | | | | | in tight spin loops, not in these edge cases where we restart a much larger loop only a few times. Reviewed by: attilio
* Tweak a few comments on adaptive spinning.jhb2009-05-291-2/+5
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* Add the OpenSolaris dtrace lockstat provider. The lockstat providersson2009-05-261-9/+70
| | | | | | | | | | adds probes for mutexes, reader/writer and shared/exclusive locks to gather contention statistics and other locking information for dtrace scripts, the lockstat(1M) command and other potential consumers. Reviewed by: attilio jhb jb Approved by: gnn (mentor)
* Remove an obsolete assertion. We always wake up all waiters when unlockingjhb2009-05-201-2/+0
| | | | a mutex and never set the lock cookie == MTX_CONTESTED.
* - Wrap lock profiling state variables in #ifdef LOCK_PROFILING blocks.jeff2009-03-151-7/+17
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* - When a mutex is destroyed while locked we need to inform lock profilingjeff2009-03-141-0/+1
| | | | that it has been released.
* Teach WITNESS about the interlocks used with lockmgr. This removes a bunchjhb2008-09-101-3/+3
| | | | | | | | of spurious witness warnings since lockmgr grew witness support. Before this, every time you passed an interlock to a lockmgr lock WITNESS treated it as a LOR. Reviewed by: attilio
* Various whitespace fixes.jhb2008-09-101-9/+9
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* Add KASSERT()'s to catch attempts to recurse on spin mutexes that aren'tjhb2008-02-131-1/+9
| | | | | | marked recursable either via mtx_lock_spin() or thread_lock(). MFC after: 1 week
* Add a couple of assertions and KTR logging to thread_lock_flags() tojhb2008-02-131-1/+7
| | | | | | match mtx_lock_spin_flags(). MFC after: 1 week
* - Re-implement lock profiling in such a way that it no longer breaksjeff2007-12-151-20/+6
| | | | | | | | | | | | | | | | | | | | | | the ABI when enabled. There is no longer an embedded lock_profile_object in each lock. Instead a list of lock_profile_objects is kept per-thread for each lock it may own. The cnt_hold statistic is now always 0 to facilitate this. - Support shared locking by tracking individual lock instances and statistics in the per-thread per-instance lock_profile_object. - Make the lock profiling hash table a per-cpu singly linked list with a per-cpu static lock_prof allocator. This removes the need for an array of spinlocks and reduces cache contention between cores. - Use a seperate hash for spinlocks and other locks so that only a critical_enter() is required and not a spinlock_enter() to modify the per-cpu tables. - Count time spent spinning in the lock statistics. - Remove the LOCK_PROFILE_SHARED option as it is always supported now. - Specifically drop and release the scheduler locks in both schedulers since we track owners now. In collaboration with: Kip Macy Sponsored by: Nokia
* Make ADAPTIVE_GIANT as the default in the kernel and remove the option.attilio2007-11-281-8/+0
| | | | | | | | | | Currently, Giant is not too much contented so that it is ok to treact it like any other mutexes. Please don't forget to update your own custom config kernel files. Approved by: cognet, marcel (maintainers of arches where option is not enabled at the moment)
* Simplify the adaptive spinning algorithm in rwlock and mutex:attilio2007-11-261-29/+41
| | | | | | | | | | | | | | | | | | | | | currently, before to spin the turnstile spinlock is acquired and the waiters flag is set. This is not strictly necessary, so just spin before to acquire the spinlock and to set the flags. This will simplify a lot other functions too, as now we have the waiters flag set only if there are actually waiters. This should make wakeup/sleeping couplet faster under intensive mutex workload. This also fixes a bug in rw_try_upgrade() in the adaptive case, where turnstile_lookup() will recurse on the ts_lock lock that will never be really released [1]. [1] Reported by: jeff with Nokia help Tested by: pho, kris (earlier, bugged version of rwlock part) Discussed with: jhb [2], jeff MFC after: 1 week [2] John had a similar patch about 6.x and/or 7.x about mutexes probabilly
* Expand lock class with the "virtual" function lc_assert which will offerattilio2007-11-181-0/+10
| | | | | | | | | an unified way for all the lock primitives to express lock assertions. Currenty, lockmgrs and rmlocks don't have assertions, so just panic in that case. This will be a base for more callout improvements. Ok'ed by: jhb, jeff
* generally we are interested in what thread did something asjulian2007-11-141-1/+1
| | | | | | 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.
* - Remove the global definition of sched_lock in mutex.h to breakjeff2007-07-181-2/+0
| | | | | | | | | | | new code and third party modules which try to depend on it. - Initialize sched_lock in sched_4bsd.c. - Declare sched_lock in sparc64 pmap.c and assert that we're compiling with SCHED_4BSD to prevent accidental crashes from running ULE. This is the sole remaining file outside of the scheduler that uses the global sched_lock. Approved by: re
* - Add the proper lock profiling calls to _thread_lock().jeff2007-07-181-2/+8
| | | | | Obtained from: kipmacy Approved by: re
* Propagate volatile qualifier to make gcc4.2 happy.mjacob2007-06-091-1/+1
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* Remove the MUTEX_WAKE_ALL option and make it the default behaviour for ourattilio2007-06-081-37/+0
| | | | | | mutexes. Currently we alredy force MUTEX_WAKE_ALL beacause of some problems with the !MUTEX_WAKE_ALL case (unavioidable priority inversion).
* - Placing the 'volatile' on the right side of the * in the td_lockjeff2007-06-061-3/+3
| | | | | | declaration removes the need for __DEVOLATILE(). Pointed out by: tegge
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