Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934973Ab3E3QCy (ORCPT ); Thu, 30 May 2013 12:02:54 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50853 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934453Ab3E3QCI (ORCPT ); Thu, 30 May 2013 12:02:08 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Namhyung Kim , Namhyung Kim , David Ahern , Ingo Molnar , Jiri Olsa , Paul Mackerras , Peter Zijlstra , Stephane Eranian , Arnaldo Carvalho de Melo Subject: [PATCH 22/66] perf report: Don't bother locking when adding hist entries Date: Thu, 30 May 2013 19:00:55 +0300 Message-Id: <1369929699-8724-23-git-send-email-acme@infradead.org> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1369929699-8724-1-git-send-email-acme@infradead.org> References: <1369929699-8724-1-git-send-email-acme@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2635 Lines: 66 From: Namhyung Kim The 'perf report'command is single-threaded, so no need to grab a lock. Although the fast path of pthread_mutex_[un]lock() is very fast, there's a ~3% gain by eliminating it when we have huge sample data. $ perf record -a -F 100000 -o perf.data.bench -- perf bench sched all $ perf record -e cycles:upp -o perf.data.before -- \ > perf report -i perf.data.bench --stdio > /dev/null ... apply this patch ... $ perf record -e cycles:upp -o perf.data.after -- \ > perf report -i perf.data.bench --stdio > /dev/null $ perf diff perf.data.{before,after} | grep pthread +0.02% libpthread-2.15.so [.] _pthread_cleanup_push_defer +0.02% libpthread-2.15.so [.] _pthread_cleanup_pop_restore 0.05% -0.05% perf [.] pthread_mutex_unlock@plt 0.05% -0.05% perf [.] pthread_mutex_lock@plt 1.01% -1.01% libpthread-2.15.so [.] pthread_mutex_lock 1.68% -1.68% libpthread-2.15.so [.] __pthread_mutex_unlock_usercnt 0.05% -0.05% libpthread-2.15.so [.] pthread_mutex_unlock Signed-off-by: Namhyung Kim Acked-by: Jiri Olsa Cc: David Ahern Cc: Ingo Molnar Cc: Jiri Olsa Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1368497347-9628-6-git-send-email-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-report.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c index 63febd2..0f0cf24 100644 --- a/tools/perf/builtin-report.c +++ b/tools/perf/builtin-report.c @@ -312,8 +312,6 @@ static int process_sample_event(struct perf_tool *tool, if (rep->cpu_list && !test_bit(sample->cpu, rep->cpu_bitmap)) return 0; - pthread_mutex_lock(&evsel->hists.lock); - if (sort__mode == SORT_MODE__BRANCH) { ret = perf_report__add_branch_hist_entry(tool, &al, sample, evsel, machine); @@ -332,8 +330,6 @@ static int process_sample_event(struct perf_tool *tool, if (ret < 0) pr_debug("problem incrementing symbol period, skipping event\n"); } - pthread_mutex_unlock(&evsel->hists.lock); - return ret; } -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/