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perf, x86: P4 PMU -- handle unflagged events

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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>
This commit is contained in:
Cyrill Gorcunov 2010-05-17 16:13:04 +08:00 committed by Ingo Molnar
parent 32ec6acfdc
commit 0db1a7bc00
1 changed files with 16 additions and 16 deletions
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32
arch/x86/kernel/cpu/perf_event_p4.c
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@ -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;