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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-04-06 11:45:13 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-07 10:49:01 +0200 |
| commit | bce379bf358738ab8efc8cda2594a299ac685085 (patch) | |
| tree | 0840adf32eefc15c5c07e7487c192fd270643057 | |
| parent | 849691a6cd40270ff5f4a8846d5f6bf8df663ffc (diff) | |
| download | linux-bce379bf358738ab8efc8cda2594a299ac685085.tar.gz linux-bce379bf358738ab8efc8cda2594a299ac685085.tar.bz2 linux-bce379bf358738ab8efc8cda2594a299ac685085.zip | |
perf_counter: minimize context time updates
Push the update_context_time() calls up the stack so that we get less
invokations and thereby a less noisy output:
before:
# ./perfstat -e 1:0 -e 1:1 -e 1:1 -e 1:1 -l ls > /dev/null
Performance counter stats for 'ls':
10.163691 cpu clock ticks (msecs) (scaled from 98.94%)
10.215360 task clock ticks (msecs) (scaled from 98.18%)
10.185549 task clock ticks (msecs) (scaled from 98.53%)
10.183581 task clock ticks (msecs) (scaled from 98.71%)
Wall-clock time elapsed: 11.912858 msecs
after:
# ./perfstat -e 1:0 -e 1:1 -e 1:1 -e 1:1 -l ls > /dev/null
Performance counter stats for 'ls':
9.316630 cpu clock ticks (msecs)
9.280789 task clock ticks (msecs)
9.280789 task clock ticks (msecs)
9.280789 task clock ticks (msecs)
Wall-clock time elapsed: 9.574872 msecs
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.618876874@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | kernel/perf_counter.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index f4f7596f7841..863703b3158f 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -319,6 +319,8 @@ static void __perf_counter_disable(void *info) spin_lock_irqsave(&ctx->lock, flags); + update_context_time(ctx); + /* * If the counter is on, turn it off. * If it is in error state, leave it in error state. @@ -797,6 +799,8 @@ void perf_counter_task_sched_out(struct task_struct *task, int cpu) if (likely(!cpuctx->task_ctx)) return; + update_context_time(ctx); + regs = task_pt_regs(task); perf_swcounter_event(PERF_COUNT_CONTEXT_SWITCHES, 1, 1, regs); __perf_counter_sched_out(ctx, cpuctx); @@ -2336,7 +2340,6 @@ static void task_clock_perf_counter_update(struct perf_counter *counter) u64 prev, now; s64 delta; - update_context_time(counter->ctx); now = counter->ctx->time; prev = atomic64_xchg(&counter->hw.prev_count, now); @@ -2349,7 +2352,6 @@ static int task_clock_perf_counter_enable(struct perf_counter *counter) struct hw_perf_counter *hwc = &counter->hw; u64 now; - update_context_time(counter->ctx); now = counter->ctx->time; atomic64_set(&hwc->prev_count, now); @@ -2372,6 +2374,7 @@ static void task_clock_perf_counter_disable(struct perf_counter *counter) static void task_clock_perf_counter_read(struct perf_counter *counter) { + update_context_time(counter->ctx); task_clock_perf_counter_update(counter); } |