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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 /kernel | |
| parent | 22a867d81707b0a2720bb5f65255265b95d30526 (diff) | |
| download | op-kernel-dev-335d7afbfb71faac833734a94240c1e07cf0ead8.zip op-kernel-dev-335d7afbfb71faac833734a94240c1e07cf0ead8.tar.gz | |
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 'kernel')
| -rw-r--r-- | kernel/mutex.c | 2 | ||||
| -rw-r--r-- | kernel/sched.c | 3 |
2 files changed, 3 insertions, 2 deletions
diff --git a/kernel/mutex.c b/kernel/mutex.c index 200407c..a5889fb 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -199,7 +199,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, * memory barriers as we'll eventually observe the right * values at the cost of a few extra spins. */ - cpu_relax(); + arch_mutex_cpu_relax(); } #endif spin_lock_mutex(&lock->wait_lock, flags); diff --git a/kernel/sched.c b/kernel/sched.c index 3e8a7db..abe7aec 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -75,6 +75,7 @@ #include <asm/tlb.h> #include <asm/irq_regs.h> +#include <asm/mutex.h> #include "sched_cpupri.h" #include "workqueue_sched.h" @@ -3888,7 +3889,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner) if (task_thread_info(rq->curr) != owner || need_resched()) return 0; - cpu_relax(); + arch_mutex_cpu_relax(); } return 1; |
