[tip:perf/core] perf/x86/intel: Move PMU ACK to after LBR read
From: tip-bot for Andi Kleen
Date: Tue Aug 04 2015 - 05:06:32 EST
Commit-ID: 0f29e573dd32bb8598e74271454e97c962da5e05
Gitweb: http://git.kernel.org/tip/0f29e573dd32bb8598e74271454e97c962da5e05
Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
AuthorDate: Sun, 10 May 2015 12:22:47 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 4 Aug 2015 10:16:58 +0200
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 <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: eranian@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1431285767-27027-10-git-send-email-andi@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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
--
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