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* [patch 0/8] mutex subsystem, ANNOUNCE
@ 2005-12-21 22:36 Ingo Molnar
  0 siblings, 0 replies; 15+ messages in thread
From: Ingo Molnar @ 2005-12-21 22:36 UTC (permalink / raw)
  To: Linus Torvalds
  Cc: lkml, Andrew Morton, Arjan van de Ven, Jes Sorensen,
	Zwane Mwaikambo, Oleg Nesterov, David Howells, Alan Cox,
	Benjamin LaHaise, Steven Rostedt, Christoph Hellwig, Andi Kleen,
	Russell King, Nicolas Pitre

this is the latest version of the mutex subsystem patch-queue. It 
consists of the following patches:

 xfs-mutex-namespace-collision-fix.patch
 add-atomic-xchg.patch
 add-atomic-call-func-i386.patch
 add-atomic-call-func-x86_64.patch
 add-atomic-call-wrappers-rest.patch
 mutex-core.patch
 mutex-debug.patch
 mutex-debug-more.patch

the patches are against Linus' latest tree.

Changes since the previous version:

- fixed the %eax clobber bug noticed by Linus. Also fixed a similar bug
  in the x86_64 assembly routine. Ended up solving this by marking the 
  register clobbered - the function-always-returns change resulted in 
  worse code. (usually the slowpath functions dont have the atomic-lock 
  parameter ready at the end of the function, so they have to do extra 
  work to return it.)

- implemented Oleg's suggestion of doing the xchg() before adding the 
  waiter to the queue.

- optimization: in the xchg() case we can avoid hitting the slowpath 
  when releasing the lock later on, by setting the count to 0 if the 
  wait-list is otherwise empty. This is the common-case for wakeups.

- bugfix: forgot to take a spinlock in the signal-return path.

- added a couple of likely/unlikely modifiers, based on profile output.

- inline the trylock fastpath into the mutex_trylock() function.

- move the waiter->lock field into the debug path - nothing in the 
  non-debug case was using it. This is also a small optimization for 
  the slowpath.

- optimization: do a cheaper list_del in the non-debug case. This also 
  enabled the removal of debug_remove_waiter().

- fix for the debugging branch: initialize the wait->list to empty.

	Ingo

^ permalink raw reply	[flat|nested] 15+ messages in thread
* [patch 0/8] mutex subsystem, ANNOUNCE
@ 2005-12-21 15:54 Ingo Molnar
  2005-12-21 16:04 ` Arjan van de Ven
                   ` (2 more replies)
  0 siblings, 3 replies; 15+ messages in thread
From: Ingo Molnar @ 2005-12-21 15:54 UTC (permalink / raw)
  To: Linus Torvalds
  Cc: lkml, Andrew Morton, Arjan van de Ven, Jes Sorensen,
	Zwane Mwaikambo, Oleg Nesterov, David Howells, Alan Cox,
	Benjamin LaHaise, Steven Rostedt, Christoph Hellwig, Andi Kleen,
	Russell King, Nicolas Pitre

this is the latest version of the mutex subsystem patch-queue. It 
consists of the following patches:

 xfs-mutex-namespace-collision-fix.patch
 add-atomic-xchg.patch
 add-atomic-call-func-i386.patch
 add-atomic-call-func-x86_64.patch
 add-atomic-call-wrappers-rest.patch
 mutex-core.patch
 mutex-debug.patch
 mutex-debug-more.patch

the patches are against Linus' latest tree, and were tested on i386, 
x86_64 and ia64. [the tests were also done in DEBUG_MUTEX_FULL mode, to 
make sure the code works fine. MUTEX_FULL support is not included in 
this patchqueue].

The patches can also be downloaded from:

  http://redhat.com/~mingo/generic-mutex-subsystem/

Changes since the previous version:

- dropped the semaphore-renaming and migration-helper patches. The 
  patches now contain only the pure mutex subsystem, nothing more.

- removed the fastpath dependency on __HAVE_ARCH_CMPXCHG: now every 
  architecture is able to use the generic mutex_lock/mutex_unlock 
  lockless fastpath. The quality of the fastpath is still as good as in 
  the previous version.

- added ARCH_IMPLEMENTS_MUTEX_FASTPATH for architectures that want to 
  hand-code their own fastpath. The mutex_lock_slowpath,
  mutex_unlock_slowpath and mutex_lock_interruptible_slowpath global
  functions can be used by such architectures in this case, and they 
  should implement the mutex_lock(), mutex_unlock() and
  mutex_lock_interruptible() functions themselves. I have tested this
  mechanism on x86. (but x86 wants to use the generic functions 
  otherwise, so those changes are not included in this patchqueue.)

- fixed the x86_64 register-clobber bug noticed by Zwane Mwaikambo

- XFS namespace collision fixes from Jes Sorensen

- lots of cleanups to "hide" the debugging code, it should now be much 
  less intrusive visually - kernel/mutex.c is now both smaller and 
  easier to read. There's no reduction in debugging functionality.

- cleaned up the debugging code

- unified all the externally visible debugging functions around the 
  mutex_debug_ prefix.

- added the proper atomic ops to every architecture - so in theory 
  mutexes should now work on every architectures. i386, x86_64 and ia64 
  was tested.

- created mutex-debug.h to hide some of the debugging details. Moved the 
  mm.h and sched.h debug-function declarations into this file.

- documentation updates

- eliminated the ->file, ->line debugging variant - __FUNCTION__ is good
  enough and resulted in nicer code.

- properly check for held locks in kfree() too, if DEBUG.

- check for held-lock reinitialization via mutex_init(), if DEBUG.

- more micro-optimizations: eliminated an extra spinlock drop/reacquire 
  in the slowpath.

- dropped waiter->woken, profiles showed that it triggered very rarely.

- dropped the timeout/timer bits - nothing is using them right now, we 
  can add them back later.

- new mutex_trylock() optimization on architectures that support cmpxchg.

- marked ->name as const

- fixed typo: CONFIG_DEBUG_MUTEXESS -> CONFIG_DEBUG_MUTEXES

- mb() -> smp_mb() in mutex_is_locked()

- mutex_trylock doesnt need __sched

comments, fixes, bugreports are welcome,

	Ingo

^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2005-12-22  8:37 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-12-21 22:36 [patch 0/8] mutex subsystem, ANNOUNCE Ingo Molnar
  -- strict thread matches above, loose matches on Subject: below --
2005-12-21 15:54 Ingo Molnar
2005-12-21 16:04 ` Arjan van de Ven
2005-12-21 18:07 ` Jes Sorensen
2005-12-22  2:36   ` Nick Piggin
2005-12-22  2:57     ` Nick Piggin
2005-12-22  7:19     ` Ingo Molnar
2005-12-22  7:56       ` Nick Piggin
2005-12-22  8:00         ` Arjan van de Ven
2005-12-22  8:10           ` Nick Piggin
2005-12-22  8:21             ` Arjan van de Ven
2005-12-22  8:32               ` Nick Piggin
2005-12-22  8:24         ` Ingo Molnar
2005-12-22  8:37           ` Nick Piggin
2005-12-21 22:43 ` Nicolas Pitre

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