commit e78505958cf123048fb48cb56b79cebb8edd15fb
author Peter Zijlstra <a.p.zijlstra@chello.nl> Fri May 21 14:43:08 2010 +0200
committer Ingo Molnar <mingo@elte.hu> Wed Jun 09 11:12:37 2010 +0200
tree 3688d124cdc906cbe9f6587c8671ba0a14c95262
parent a6e6dea68c18f705957573ee5596097c7e82d0e5

perf: Convert perf_event to local_t

Since now all modification to event->count (and ->prev_count
and ->period_left) are local to a cpu, change then to local64_t so we
avoid the LOCK'ed ops.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/perf_event.c

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 79e1998..2d0d290 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -296,10 +296,10 @@
 	 * count to the generic event atomically:
 	 */
 again:
-	prev_raw_count = atomic64_read(&hwc->prev_count);
+	prev_raw_count = local64_read(&hwc->prev_count);
 	rdmsrl(hwc->event_base + idx, new_raw_count);
 
-	if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
+	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
 					new_raw_count) != prev_raw_count)
 		goto again;
 
@@ -314,8 +314,8 @@
 	delta = (new_raw_count << shift) - (prev_raw_count << shift);
 	delta >>= shift;
 
-	atomic64_add(delta, &event->count);
-	atomic64_sub(delta, &hwc->period_left);
+	local64_add(delta, &event->count);
+	local64_sub(delta, &hwc->period_left);
 
 	return new_raw_count;
 }
@@ -439,7 +439,7 @@
 	if (!hwc->sample_period) {
 		hwc->sample_period = x86_pmu.max_period;
 		hwc->last_period = hwc->sample_period;
-		atomic64_set(&hwc->period_left, hwc->sample_period);
+		local64_set(&hwc->period_left, hwc->sample_period);
 	} else {
 		/*
 		 * If we have a PMU initialized but no APIC
@@ -886,7 +886,7 @@
 x86_perf_event_set_period(struct perf_event *event)
 {
 	struct hw_perf_event *hwc = &event->hw;
-	s64 left = atomic64_read(&hwc->period_left);
+	s64 left = local64_read(&hwc->period_left);
 	s64 period = hwc->sample_period;
 	int ret = 0, idx = hwc->idx;
 
@@ -898,14 +898,14 @@
 	 */
 	if (unlikely(left <= -period)) {
 		left = period;
-		atomic64_set(&hwc->period_left, left);
+		local64_set(&hwc->period_left, left);
 		hwc->last_period = period;
 		ret = 1;
 	}
 
 	if (unlikely(left <= 0)) {
 		left += period;
-		atomic64_set(&hwc->period_left, left);
+		local64_set(&hwc->period_left, left);
 		hwc->last_period = period;
 		ret = 1;
 	}
@@ -924,7 +924,7 @@
 	 * The hw event starts counting from this event offset,
 	 * mark it to be able to extra future deltas:
 	 */
-	atomic64_set(&hwc->prev_count, (u64)-left);
+	local64_set(&hwc->prev_count, (u64)-left);
 
 	wrmsrl(hwc->event_base + idx, (u64)(-left) & x86_pmu.cntval_mask);