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perf/x86/intel: Remove division from the intel_pmu_drain_pebs_nhm() hot path

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Only do the division in case we have to print the result out in a warning.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-43nl31erfbajwpfj254f6zji@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2013-09-16 09:23:02 +02:00 • committed by Ingo Molnar
parent 7f2ee91f54
commit eb8417aa70
1 changed files with 5 additions and 5 deletions
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10
arch/x86/kernel/cpu/perf_event_intel_ds.c
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@ -944,7 +944,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
struct perf_event *event = NULL; struct perf_event *event = NULL;
void *at, *top; void *at, *top;
u64 status = 0; u64 status = 0;
int bit, n; int bit;
if (!x86_pmu.pebs_active) if (!x86_pmu.pebs_active)
return; return;
@ -954,16 +954,16 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
ds->pebs_index = ds->pebs_buffer_base; ds->pebs_index = ds->pebs_buffer_base;
n = (top - at) / x86_pmu.pebs_record_size; if (unlikely(at > top))
if (n <= 0)
return; return;
/* /*
* Should not happen, we program the threshold at 1 and do not * Should not happen, we program the threshold at 1 and do not
* set a reset value. * set a reset value.
*/ */
WARN_ONCE(n > x86_pmu.max_pebs_events, WARN_ONCE(top - at > x86_pmu.max_pebs_events * x86_pmu.pebs_record_size,
"Unexpected number of pebs records %d\n", n); "Unexpected number of pebs records %ld\n",
(top - at) / x86_pmu.pebs_record_size);
for (; at < top; at += x86_pmu.pebs_record_size) { for (; at < top; at += x86_pmu.pebs_record_size) {
struct pebs_record_nhm *p = at; struct pebs_record_nhm *p = at;