From 34b133f8e94e39ff3cf4d1c1f67f2e07cdc3d54e Mon Sep 17 00:00:00 2001 From: Gerald Schaefer Date: Wed, 5 Jan 2011 12:48:14 +0100 Subject: [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 Signed-off-by: Peter Zijlstra LKML-Reference: <1290437256.7455.4.camel@thinkpad> Signed-off-by: Ingo Molnar --- arch/s390/Kconfig | 1 + arch/s390/include/asm/mutex.h | 2 ++ 2 files changed, 3 insertions(+) (limited to 'arch/s390') diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 3243f7a..c05d081 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 458c1f7..688271f 100644 --- a/arch/s390/include/asm/mutex.h +++ b/arch/s390/include/asm/mutex.h @@ -7,3 +7,5 @@ */ #include + +#define arch_mutex_cpu_relax() barrier() -- cgit v1.1