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perf_counter, x86: return raw count with x86_perf_counter_update() 

To check on AMD cpus if a counter overflows, the upper bit of the raw
counter value must be checked. This value is already internally
available in x86_perf_counter_update(). Now, the value is returned so
that it can be used directly to check for overflows.

[ Impact: micro-optimization ]

Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241002046-8832-26-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Robert Richter 2009-04-29 12:47:22 +02:00 committed by Ingo Molnar
parent a29aa8a7ff
commit 4b7bfd0d27
1 changed files with 4 additions and 3 deletions
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7
arch/x86/kernel/cpu/perf_counter.c
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@ -132,7 +132,7 @@ static u64 amd_pmu_raw_event(u64 event)
* Can only be executed on the CPU where the counter is active.
* Returns the delta events processed.
*/
static void
static u64
x86_perf_counter_update(struct perf_counter *counter,
struct hw_perf_counter *hwc, int idx)
{
@ -165,6 +165,8 @@ x86_perf_counter_update(struct perf_counter *counter,
atomic64_add(delta, &counter->count);
atomic64_sub(delta, &hwc->period_left);
return new_raw_count;
}
static atomic_t num_counters;
@ -785,8 +787,7 @@ static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi)
continue;
counter = cpuc->counters[idx];
hwc = &counter->hw;
x86_perf_counter_update(counter, hwc, idx);
val = atomic64_read(&hwc->prev_count);
val = x86_perf_counter_update(counter, hwc, idx);
if (val & (1ULL << (x86_pmu.counter_bits - 1)))
continue;
/* counter overflow */