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Date: Thu, 7 May 2015 15:56:31 -0700 From: Andi Kleen <andi@...stfloor.org> To: peterz@...radead.org Cc: kan.liang@...el.com, eranian@...gle.com, acme@...radead.org, linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com> Subject: [PATCH 8/9] perf, x86: Optimize v4 LBR unfreezing From: Andi Kleen <ak@...ux.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@...ux.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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