locking/mutexes: Correct documentation on mutex optimistic spinning
The mutex optimistic spinning documentation states that we spin for acquisition when we find that there are no pending waiters. However, in actuality, whether or not there are waiters for the mutex doesn't determine if we will spin for it. This patch removes that statement and also adds a comment which mentions that we spin for the mutex while we don't need to reschedule. Signed-off-by: Jason Low <jason.low2@hp.com> Acked-by: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: akpm@linux-foundation.org Cc: tim.c.chen@linux.intel.com Cc: paulmck@linux.vnet.ibm.com Cc: rostedt@goodmis.org Cc: Waiman.Long@hp.com Cc: scott.norton@hp.com Cc: aswin@hp.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1402511843-4721-2-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
6cc620bc8e
commit
0c3c0f0d6e
|
@ -388,12 +388,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
|
||||||
/*
|
/*
|
||||||
* Optimistic spinning.
|
* Optimistic spinning.
|
||||||
*
|
*
|
||||||
* We try to spin for acquisition when we find that there are no
|
* We try to spin for acquisition when we find that the lock owner
|
||||||
* pending waiters and the lock owner is currently running on a
|
* is currently running on a (different) CPU and while we don't
|
||||||
* (different) CPU.
|
* need to reschedule. The rationale is that if the lock owner is
|
||||||
*
|
* running, it is likely to release the lock soon.
|
||||||
* The rationale is that if the lock owner is running, it is likely to
|
|
||||||
* release the lock soon.
|
|
||||||
*
|
*
|
||||||
* Since this needs the lock owner, and this mutex implementation
|
* Since this needs the lock owner, and this mutex implementation
|
||||||
* doesn't track the owner atomically in the lock field, we need to
|
* doesn't track the owner atomically in the lock field, we need to
|
||||||
|
|
Loading…
Reference in a new issue