Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH 8/9] perf, x86: Optimize v4 LBR unfreezing | Date | Thu, 7 May 2015 15:56:31 -0700 |
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From: Andi Kleen <ak@linux.intel.com>
In Arch perfmon v4 the GLOBAL_STATUS reset automatically unfreezes LBRs. So no need to do it manually in the LBR code. Add a check to skip it.
Signed-off-by: Andi Kleen <ak@linux.intel.com> --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index 6c48c97..64d3122 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -147,6 +147,13 @@ static void __intel_pmu_lbr_enable(bool pmi) wrmsrl(MSR_LBR_SELECT, lbr_select); } + /* + * No need to unfreeze manually, as v4 can do that as part + * of the GLOBAL_STATUS ack. + */ + if (pmi && x86_pmu.version >= 4) + return; + rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); orig_debugctl = debugctl; debugctl |= DEBUGCTLMSR_LBR; -- 1.9.3
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