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| author | Gerald Schaefer <gerald.schaefer@de.ibm.com> | 2010-11-22 15:47:36 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-11-26 15:05:34 +0100 |
| commit | 335d7afbfb71faac833734a94240c1e07cf0ead8 (patch) | |
| tree | 483a24c6005af6eb25a256d92a697411d94a7458 /include | |
| parent | 22a867d81707b0a2720bb5f65255265b95d30526 (diff) | |
| download | linux-stable-335d7afbfb71faac833734a94240c1e07cf0ead8.tar.gz linux-stable-335d7afbfb71faac833734a94240c1e07cf0ead8.tar.bz2 linux-stable-335d7afbfb71faac833734a94240c1e07cf0ead8.zip | |
mutexes, sched: Introduce arch_mutex_cpu_relax()
The spinning mutex implementation uses cpu_relax() in busy loops as a
compiler barrier. Depending on the architecture, cpu_relax() may do more
than needed in this specific mutex spin loops. On System z we also give
up the time slice of the virtual cpu in cpu_relax(), which prevents
effective spinning on the mutex.
This patch replaces cpu_relax() in the spinning mutex code with
arch_mutex_cpu_relax(), which can be defined by each architecture that
selects HAVE_ARCH_MUTEX_CPU_RELAX. The default is still cpu_relax(), so
this patch should not affect other architectures than System z for now.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1290437256.7455.4.camel@thinkpad>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mutex.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index f363bc8fdc74..94b48bd40dd7 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -160,4 +160,8 @@ extern int mutex_trylock(struct mutex *lock); extern void mutex_unlock(struct mutex *lock); extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); +#ifndef CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX +#define arch_mutex_cpu_relax() cpu_relax() +#endif + #endif |