diff options
| author | Gerald Schaefer <gerald.schaefer@de.ibm.com> | 2011-01-05 12:48:14 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> | 2011-01-05 12:47:31 +0100 |
| commit | 34b133f8e94e39ff3cf4d1c1f67f2e07cdc3d54e (patch) | |
| tree | 462da9df24831e825deca5987e0fd283034cdfde /arch | |
| parent | c03017544e3b2e60aa3c8ae451fac01595f1bf11 (diff) | |
[S390] mutex: 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 'arch')
| -rw-r--r-- | arch/Kconfig | 3 | ||||
| -rw-r--r-- | arch/s390/Kconfig | 1 | ||||
| -rw-r--r-- | arch/s390/include/asm/mutex.h | 2 |
3 files changed, 6 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 8bf0fa652eb..f78c2be4242 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -175,4 +175,7 @@ config HAVE_PERF_EVENTS_NMI config HAVE_ARCH_JUMP_LABEL bool +config HAVE_ARCH_MUTEX_CPU_RELAX + bool + source "kernel/gcov/Kconfig" diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 3243f7a52c7..c05d0819f56 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -87,6 +87,7 @@ config S390 select HAVE_KERNEL_LZMA select HAVE_KERNEL_LZO select HAVE_GET_USER_PAGES_FAST + select HAVE_ARCH_MUTEX_CPU_RELAX select ARCH_INLINE_SPIN_TRYLOCK select ARCH_INLINE_SPIN_TRYLOCK_BH select ARCH_INLINE_SPIN_LOCK diff --git a/arch/s390/include/asm/mutex.h b/arch/s390/include/asm/mutex.h index 458c1f7fbc1..688271f5f2e 100644 --- a/arch/s390/include/asm/mutex.h +++ b/arch/s390/include/asm/mutex.h @@ -7,3 +7,5 @@ */ #include <asm-generic/mutex-dec.h> + +#define arch_mutex_cpu_relax() barrier() |