diff options
| author | Robert Richter <robert.richter@amd.com> | 2009-04-29 12:47:02 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-29 14:51:02 +0200 |
| commit | 527e26af3741a2168986d8b82653ffe173891324 (patch) | |
| tree | 07ef21f4a87badb3252ee9631d6809c7ff597aea /arch | |
| parent | 4295ee62660b13ddb87d41539f49b239e6e7d56f (diff) | |
perf_counter, x86: protect per-cpu variables with compile barriers only
Per-cpu variables needn't to be protected with cpu barriers
(smp_wmb()). Protection is only needed for preemption on the same cpu
(rescheduling or the nmi handler). This can be done using a compiler
barrier only.
[ Impact: micro-optimization ]
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241002046-8832-6-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 75a090394b6..ad663d5ad2d 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -673,7 +673,7 @@ try_generic: /* * Make it visible before enabling the hw: */ - smp_wmb(); + barrier(); __hw_perf_counter_set_period(counter, hwc, idx); __pmc_generic_enable(counter, hwc, idx); @@ -745,7 +745,7 @@ static void pmc_generic_disable(struct perf_counter *counter) * Make sure the cleared pointer becomes visible before we * (potentially) free the counter: */ - smp_wmb(); + barrier(); /* * Drain the remaining delta count out of a counter |