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authorCyrill Gorcunov <gorcunov@openvz.org>2010-05-17 16:13:04 +0800
committerIngo Molnar <mingo@elte.hu>2010-05-18 08:25:34 +0200
commit0db1a7bc00216a981d0b7056627ad8682f4f0636 (patch)
treead4036506ee871280a5e83eae757e2d7316462e2 /arch/x86
parent32ec6acfdcc066313261d0fbe6a966cb1804a7cd (diff)
downloadop-kernel-dev-0db1a7bc00216a981d0b7056627ad8682f4f0636.zip
op-kernel-dev-0db1a7bc00216a981d0b7056627ad8682f4f0636.tar.gz
perf, x86: P4 PMU -- handle unflagged events
It might happen that an event can overflow without the proper overflow flag set. Check the sign bit in the raw counter value to solve this problem. Tested-by: Lin Ming <ming.m.lin@intel.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: fweisbec@gmail.com Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <1274083984.6540.15.camel@minggr.sh.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/perf_event_p4.c32
1 files changed, 16 insertions, 16 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 424fc8d..02f0728 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -465,15 +465,21 @@ out:
return rc;
}
-static inline void p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc)
+static inline int p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc)
{
- unsigned long dummy;
+ int overflow = 0;
+ u32 low, high;
- rdmsrl(hwc->config_base + hwc->idx, dummy);
- if (dummy & P4_CCCR_OVF) {
+ rdmsr(hwc->config_base + hwc->idx, low, high);
+
+ /* we need to check high bit for unflagged overflows */
+ if ((low & P4_CCCR_OVF) || (high & (1 << 31))) {
+ overflow = 1;
(void)checking_wrmsrl(hwc->config_base + hwc->idx,
- ((u64)dummy) & ~P4_CCCR_OVF);
+ ((u64)low) & ~P4_CCCR_OVF);
}
+
+ return overflow;
}
static inline void p4_pmu_disable_event(struct perf_event *event)
@@ -584,21 +590,15 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
WARN_ON_ONCE(hwc->idx != idx);
- /*
- * FIXME: Redundant call, actually not needed
- * but just to check if we're screwed
- */
- p4_pmu_clear_cccr_ovf(hwc);
+ /* it might be unflagged overflow */
+ handled = p4_pmu_clear_cccr_ovf(hwc);
val = x86_perf_event_update(event);
- if (val & (1ULL << (x86_pmu.cntval_bits - 1)))
+ if (!handled && (val & (1ULL << (x86_pmu.cntval_bits - 1))))
continue;
- /*
- * event overflow
- */
- handled = 1;
- data.period = event->hw.last_period;
+ /* event overflow for sure */
+ data.period = event->hw.last_period;
if (!x86_perf_event_set_period(event))
continue;
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