From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755215AbZKUNm0 (ORCPT ); Sat, 21 Nov 2009 08:42:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755151AbZKUNmY (ORCPT ); Sat, 21 Nov 2009 08:42:24 -0500 Received: from hera.kernel.org ([140.211.167.34]:60872 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755124AbZKUNmV (ORCPT ); Sat, 21 Nov 2009 08:42:21 -0500 Date: Sat, 21 Nov 2009 13:41:42 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, 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, mingo@elte.hu In-Reply-To: <20091120212508.452227115@chello.nl> References: <20091120212508.452227115@chello.nl> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Optimize perf_event_task_ctx() Message-ID: Git-Commit-ID: d6ff86cfb50a72df820e7e839836d55d245306fb X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: d6ff86cfb50a72df820e7e839836d55d245306fb Gitweb: http://git.kernel.org/tip/d6ff86cfb50a72df820e7e839836d55d245306fb Author: Peter Zijlstra AuthorDate: Fri, 20 Nov 2009 22:19:46 +0100 Committer: Ingo Molnar CommitDate: Sat, 21 Nov 2009 14:11:36 +0100 perf: Optimize perf_event_task_ctx() Remove a rcu_read_{,un}lock() pair and a few conditionals. We can remove the rcu_read_lock() by increasing the scope of one in the calling function. We can do away with the system_state check if the machine still boots after this patch (seems to be the case). We can do away with the list_empty() check because the bare list_for_each_entry_rcu() reduces to that now that we've removed everything else. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras LKML-Reference: <20091120212508.452227115@chello.nl> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 7 +------ 1 files changed, 1 insertions(+), 6 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index cda17ac..2afb305 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3267,15 +3267,10 @@ static void perf_event_task_ctx(struct perf_event_context *ctx, { struct perf_event *event; - if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) - return; - - rcu_read_lock(); list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { if (perf_event_task_match(event)) perf_event_task_output(event, task_event); } - rcu_read_unlock(); } static void perf_event_task_event(struct perf_task_event *task_event) @@ -3283,11 +3278,11 @@ static void perf_event_task_event(struct perf_task_event *task_event) struct perf_cpu_context *cpuctx; struct perf_event_context *ctx = task_event->task_ctx; + rcu_read_lock(); cpuctx = &get_cpu_var(perf_cpu_context); perf_event_task_ctx(&cpuctx->ctx, task_event); put_cpu_var(perf_cpu_context); - rcu_read_lock(); if (!ctx) ctx = rcu_dereference(task_event->task->perf_event_ctxp); if (ctx)