From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757332AbZDGJN2 (ORCPT ); Tue, 7 Apr 2009 05:13:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756475AbZDGJKV (ORCPT ); Tue, 7 Apr 2009 05:10:21 -0400 Received: from hera.kernel.org ([140.211.167.34]:39067 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756389AbZDGJKT (ORCPT ); Tue, 7 Apr 2009 05:10:19 -0400 Date: Tue, 7 Apr 2009 09:09:38 GMT From: Peter Zijlstra To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, cjashfor@linux.vnet.ibm.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de, cjashfor@linux.vnet.ibm.com, mingo@elte.hu In-Reply-To: <20090406094518.618876874@chello.nl> References: <20090406094518.618876874@chello.nl> Subject: [tip:perfcounters/core] perf_counter: minimize context time updates Message-ID: Git-Commit-ID: bce379bf358738ab8efc8cda2594a299ac685085 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Tue, 07 Apr 2009 09:09:40 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: bce379bf358738ab8efc8cda2594a299ac685085 Gitweb: http://git.kernel.org/tip/bce379bf358738ab8efc8cda2594a299ac685085 Author: Peter Zijlstra AuthorDate: Mon, 6 Apr 2009 11:45:13 +0200 Committer: Ingo Molnar CommitDate: Tue, 7 Apr 2009 10:49:01 +0200 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 Cc: Paul Mackerras Cc: Corey Ashford LKML-Reference: <20090406094518.618876874@chello.nl> Signed-off-by: Ingo Molnar --- 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 f4f7596..863703b 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); }