From 0f29e573dd32bb8598e74271454e97c962da5e05 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sun, 10 May 2015 12:22:47 -0700 Subject: [PATCH] perf/x86/intel: Move PMU ACK to after LBR read With Arch Perfmon v4 the PMU ack unfreezes the LBRs. So we need to do the PMU ack after the LBR reading, otherwise the LBRs would be polluted by the PMI handler. This is a minimal change. In principle the ACK could be moved much later. Signed-off-by: Andi Kleen Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: eranian@google.com Link: http://lkml.kernel.org/r/1431285767-27027-10-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 52c9ded..da93b4b 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1594,6 +1594,7 @@ static int intel_pmu_handle_irq(struct pt_regs *regs) loops = 0; again: + intel_pmu_lbr_read(); intel_pmu_ack_status(status); if (++loops > 100) { static bool warned = false; @@ -1608,7 +1609,6 @@ again: inc_irq_stat(apic_perf_irqs); - intel_pmu_lbr_read(); /* * Ignore a range of extra bits in status that do not indicate -- 2.7.4