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2009-04-29mutex: add atomic_dec_and_mutex_lock()Eric Paris1-0/+23
Much like the atomic_dec_and_lock() function in which we take an hold a spin_lock if we drop the atomic to 0 this function takes and holds the mutex if we dec the atomic to 0. Signed-off-by: Eric Paris <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Cc: Paul Mackerras <[email protected]> Orig-LKML-Reference: <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2009-01-14mutex: implement adaptive spinningPeter Zijlstra1-2/+3
Change mutex contention behaviour such that it will sometimes busy wait on acquisition - moving its behaviour closer to that of spinlocks. This concept got ported to mainline from the -rt tree, where it was originally implemented for rtmutexes by Steven Rostedt, based on work by Gregory Haskins. Testing with Ingo's test-mutex application (http://lkml.org/lkml/2006/1/8/50) gave a 345% boost for VFS scalability on my testbox: # ./test-mutex-shm V 16 10 | grep "^avg ops" avg ops/sec: 296604 # ./test-mutex-shm V 16 10 | grep "^avg ops" avg ops/sec: 85870 The key criteria for the busy wait is that the lock owner has to be running on a (different) cpu. The idea is that as long as the owner is running, there is a fair chance it'll release the lock soon, and thus we'll be better off spinning instead of blocking/scheduling. Since regular mutexes (as opposed to rtmutexes) do not atomically track the owner, we add the owner in a non-atomic fashion and deal with the races in the slowpath. Furthermore, to ease the testing of the performance impact of this new code, there is means to disable this behaviour runtime (without having to reboot the system), when scheduler debugging is enabled (CONFIG_SCHED_DEBUG=y), by issuing the following command: # echo NO_OWNER_SPIN > /debug/sched_features This command re-enables spinning again (this is also the default): # echo OWNER_SPIN > /debug/sched_features Signed-off-by: Peter Zijlstra <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2008-10-30mutex: improve header comment to be actually informative about the APIArjan van de Ven1-0/+2
Impact: improve documentation It's nice to say that mutex_trylock follows the spin_trylock convention. It's a lot nicer if the comment also says which that is... make it so. Signed-off-by: Arjan van de Ven <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
2008-02-08Remove fastcall from linux/includeHarvey Harrison1-6/+6
[[email protected]: coding-style fixes] Signed-off-by: Harvey Harrison <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2007-12-06Add mutex_lock_killableLiam R. Howlett1-0/+5
Similar to mutex_lock_interruptible, it can be interrupted by a fatal signal only. Signed-off-by: Liam R. Howlett <[email protected]> Acked-by: Ingo Molnar <[email protected]> Signed-off-by: Matthew Wilcox <[email protected]>
2007-10-17Mutex documentation is unclear about software interrupts, tasklets and timersMatti Linnanvuori1-1/+2
Acked-by: Arjan van de Ven <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2007-10-11lockdep: fixup mutex annotationsPeter Zijlstra1-3/+6
The fancy mutex_lock fastpath has too many indirections to track the caller hence all contentions are perceived to come from mutex_lock(). Avoid this by explicitly not using the fastpath code (it was disabled already anyway). Signed-off-by: Peter Zijlstra <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2007-05-09mutex_lock_interruptible(): add __must_checkAndrew Morton1-2/+3
It's not sane to use mutex_lock_interruptible() and to then ignore the result. Ditto down_interruptible(), but I'm lazy. Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2007-01-26[PATCH] fix various kernel-doc in header filesRobert P. J. Day1-1/+1
Fix a number of kernel-doc entries for header files in include/linux by making sure they begin with the appropriate '/**' notation and use @var notation. Signed-off-by: Robert P. J. Day <[email protected]> Signed-off-by: Randy Dunlap <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2006-12-08[PATCH] lockdep: avoid lockdep warning in mdNeilBrown1-0/+2
md_open takes ->reconfig_mutex which causes lockdep to complain. This (normally) doesn't have deadlock potential as the possible conflict is with a reconfig_mutex in a different device. I say "normally" because if a loop were created in the array->member hierarchy a deadlock could happen. However that causes bigger problems than a deadlock and should be fixed independently. So we flag the lock in md_open as a nested lock. This requires defining mutex_lock_interruptible_nested. Cc: Ingo Molnar <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Acked-by: Ingo Molnar <[email protected]> Signed-off-by: Neil Brown <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2006-12-07[PATCH] lockdep: name some old style locksPeter Zijlstra1-1/+1
Name some of the remaning 'old_style_spin_init' locks Signed-off-by: Peter Zijlstra <[email protected]> Acked-by: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2006-07-03[PATCH] lockdep: prove mutex locking correctnessIngo Molnar1-3/+28
Use the lock validator framework to prove mutex locking correctness. Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Arjan van de Ven <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2006-07-03[PATCH] lockdep: better lock debuggingIngo Molnar1-6/+0
Generic lock debugging: - generalized lock debugging framework. For example, a bug in one lock subsystem turns off debugging in all lock subsystems. - got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from the mutex/rtmutex debugging code: it caused way too much prototype hackery, and lockdep will give the same information anyway. - ability to do silent tests - check lock freeing in vfree too. - more finegrained debugging options, to allow distributions to turn off more expensive debugging features. There's no separate 'held mutexes' list anymore - but there's a 'held locks' stack within lockdep, which unifies deadlock detection across all lock classes. (this is independent of the lockdep validation stuff - lockdep first checks whether we are holding a lock already) Here are the current debugging options: CONFIG_DEBUG_MUTEXES=y CONFIG_DEBUG_LOCK_ALLOC=y which do: config DEBUG_MUTEXES bool "Mutex debugging, basic checks" config DEBUG_LOCK_ALLOC bool "Detect incorrect freeing of live mutexes" Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Arjan van de Ven <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2006-01-11[PATCH] fix/simplify mutex debugging codeDavid Woodhouse1-1/+1
Let's switch mutex_debug_check_no_locks_freed() to take (addr, len) as arguments instead, since all its callers were just calculating the 'to' address for themselves anyway... (and sometimes doing so badly). Signed-off-by: David Woodhouse <[email protected]> Acked-by: Ingo Molnar <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2006-01-11[MUTEX]: linux/mutex.h needs linux/linkage.h tooDavid S. Miller1-0/+1
Signed-off-by: David S. Miller <[email protected]>
2006-01-09[PATCH] mutex subsystem, coreIngo Molnar1-0/+119
mutex implementation, core files: just the basic subsystem, no users of it. Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Arjan van de Ven <[email protected]>
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