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authorCyrill Gorcunov <gorcunov@openvz.org>2010-08-05 19:09:17 +0400
committerIngo Molnar <mingo@elte.hu>2010-08-08 22:53:50 +0200
commit1c250d709fdc8aa5bf42d90be99428a01a256a55 (patch)
treee71c6d304b12017a034a6ad26468abe296ea5a6c /arch/x86
parentef8f34aabf2450a9fb36b2c87fe0ea0b86a38195 (diff)
downloadlinux-1c250d709fdc8aa5bf42d90be99428a01a256a55.tar.bz2
perf, x86: P4 PMU -- update nmi irq statistics and unmask lvt entry properly
In case if last active performance counter is not overflowed at moment of NMI being triggered by another counter, the irq statistics may miss an update stage. As a more serious consequence -- apic quirk may not be triggered so apic lvt entry stay masked. Tested-by: Lin Ming <ming.m.lin@intel.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Stephane Eranian <eranian@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20100805150917.GA6311@lenovo> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/perf_event_p4.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 107711bf0ee8..febb12cea795 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -656,6 +656,7 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
cpuc = &__get_cpu_var(cpu_hw_events);
for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+ int overflow;
if (!test_bit(idx, cpuc->active_mask))
continue;
@@ -666,12 +667,14 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
WARN_ON_ONCE(hwc->idx != idx);
/* it might be unflagged overflow */
- handled = p4_pmu_clear_cccr_ovf(hwc);
+ overflow = p4_pmu_clear_cccr_ovf(hwc);
val = x86_perf_event_update(event);
- if (!handled && (val & (1ULL << (x86_pmu.cntval_bits - 1))))
+ if (!overflow && (val & (1ULL << (x86_pmu.cntval_bits - 1))))
continue;
+ handled += overflow;
+
/* event overflow for sure */
data.period = event->hw.last_period;
@@ -687,7 +690,7 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
inc_irq_stat(apic_perf_irqs);
}
- return handled;
+ return handled > 0;
}
/*