Commit-ID: 1c80f4b598d9b075a2a0be694e28be93a6702bcc Gitweb: http://git.kernel.org/tip/1c80f4b598d9b075a2a0be694e28be93a6702bcc Author: Ingo Molnar <mingo@xxxxxxx> AuthorDate: Fri, 15 May 2009 08:25:22 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Fri, 15 May 2009 09:47:05 +0200 perf_counter: x86: Disallow interval of 1 On certain CPUs i have observed a stuck PMU if interval was set to 1 and NMIs were used. The PMU had PMC0 set in MSR_CORE_PERF_GLOBAL_STATUS, but it was not possible to ack it via MSR_CORE_PERF_GLOBAL_OVF_CTRL, and the NMI loop got stuck infinitely. [ Impact: fix rare hangs during high perfcounter load ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- arch/x86/kernel/cpu/perf_counter.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 1dcf670..46a82d1 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -473,6 +473,11 @@ x86_perf_counter_set_period(struct perf_counter *counter, left += period; atomic64_set(&hwc->period_left, left); } + /* + * Quirk: certain CPUs dont like it if just 1 event is left: + */ + if (unlikely(left < 2)) + left = 2; per_cpu(prev_left[idx], smp_processor_id()) = left; -- 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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