diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-06-10 13:40:57 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-06-10 16:55:26 +0200 |
| commit | bd2b5b12849a3446abad0b25e920f86f5480b309 (patch) | |
| tree | b0eacf6002f2015c0483390619a3f874bcb7e7d2 /arch/x86/kernel/cpu/perf_counter.c | |
| parent | dc81081b2d9a6a9d64dad1bef1e5fc9fb660e53e (diff) | |
perf_counter: More aggressive frequency adjustment
Also employ the overflow handler to adjust the frequency, this results
in a stable frequency in about 40~50 samples, instead of that many ticks.
This also means we can start sampling at a sample period of 1 without
running head-first into the throttle.
It relies on sched_clock() to accurately measure the time difference
between the overflow NMIs.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/cpu/perf_counter.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 49f258537cb..240ca563063 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -696,10 +696,11 @@ static int __hw_perf_counter_init(struct perf_counter *counter) if (!attr->exclude_kernel) hwc->config |= ARCH_PERFMON_EVENTSEL_OS; - if (!hwc->sample_period) + if (!hwc->sample_period) { hwc->sample_period = x86_pmu.max_period; + atomic64_set(&hwc->period_left, hwc->sample_period); + } - atomic64_set(&hwc->period_left, hwc->sample_period); counter->destroy = hw_perf_counter_destroy; /* |