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authorRobert Richter <robert.richter@amd.com>2009-04-29 12:47:22 +0200
committerIngo Molnar <mingo@elte.hu>2009-04-29 14:51:13 +0200
commit4b7bfd0d276da3a006d37e85d3cf900d7a14ae2a (patch)
treeed4fe623afebdeb17e0a9ccc833f2154cd815991 /arch
parenta29aa8a7ff93e4196d558036928597e68337dd8d (diff)
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_counter.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index f4d59d4cf3f..a8a53abd706 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -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 @@ again:
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 */