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Message-Id: <1431285767-27027-9-git-send-email-andi@firstfloor.org> Date: Sun, 10 May 2015 12:22:46 -0700 From: Andi Kleen <andi@...stfloor.org> To: peterz@...radead.org Cc: eranian@...gle.com, linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com> Subject: [PATCH 8/9] x86, perf: 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. v2: Move test up to beginning of function. 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..ae54ea9 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -139,6 +139,13 @@ static void __intel_pmu_lbr_enable(bool pmi) u64 debugctl, lbr_select = 0, orig_debugctl; /* + * No need to unfreeze manually, as v4 can do that as part + * of the GLOBAL_STATUS ack. + */ + if (pmi && x86_pmu.version >= 4) + return; + + /* * No need to reprogram LBR_SELECT in a PMI, as it * did not change. */ -- 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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