Commit-ID: d2517a49d55536b38c7a87e5289550cfedaa4dcc Gitweb: http://git.kernel.org/tip/d2517a49d55536b38c7a87e5289550cfedaa4dcc Author: Ingo Molnar <mingo@xxxxxxx> AuthorDate: Sun, 17 May 2009 10:04:45 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Sun, 17 May 2009 12:27:37 +0200 perf_counter, x86: fix zero irq_period counters The quirk to irq_period unearthed an unrobustness we had in the hw_counter initialization sequence: we left irq_period at 0, which was then quirked up to 2 ... which then generated a _lot_ of interrupts during 'perf stat' runs, slowed them down and skewed the counter results in general. Initialize irq_period to the maximum instead. [ Impact: fix perf stat results ] Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Srivatsa Vaddagiri <vatsa@xxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- arch/x86/kernel/cpu/perf_counter.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 886dcf3..5bfd30a 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -286,6 +286,9 @@ static int __hw_perf_counter_init(struct perf_counter *counter) hwc->nmi = 1; } + if (!hwc->irq_period) + hwc->irq_period = x86_pmu.max_period; + atomic64_set(&hwc->period_left, min(x86_pmu.max_period, hwc->irq_period)); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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