From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756265AbZKTVcX (ORCPT ); Fri, 20 Nov 2009 16:32:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755907AbZKTVbh (ORCPT ); Fri, 20 Nov 2009 16:31:37 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:34634 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755669AbZKTV22 (ORCPT ); Fri, 20 Nov 2009 16:28:28 -0500 Message-Id: <20091120212508.779516394@chello.nl> References: <20091120211942.676891948@chello.nl> User-Agent: quilt/0.46-1 Date: Fri, 20 Nov 2009 22:19:50 +0100 From: Peter Zijlstra To: Paul Mackerras , Ingo Molnar , Peter Zijlstra Cc: linux-kernel@vger.kernel.org Subject: [PATCH 08/15] perf: optimize perf_event_task_sched_out Content-Disposition: inline; filename=perf-time-1.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Remove an update_context_time() call from the perf_event_task_sched_out() path and into the branch its needed. The call was both superfluous, because __perf_event_sched_out() already does it, and wrong, because it was done without holding ctx->lock. Place it in perf_event_sync_stat(), which is the only place it is needed and which does already hold ctx->lock. Signed-off-by: Peter Zijlstra --- kernel/perf_event.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux-2.6/kernel/perf_event.c =================================================================== --- linux-2.6.orig/kernel/perf_event.c +++ linux-2.6/kernel/perf_event.c @@ -1120,6 +1120,8 @@ static void perf_event_sync_stat(struct if (!ctx->nr_stat) return; + update_context_time(ctx); + event = list_first_entry(&ctx->event_list, struct perf_event, event_entry); @@ -1163,8 +1165,6 @@ void perf_event_task_sched_out(struct ta if (likely(!ctx || !cpuctx->task_ctx)) return; - update_context_time(ctx); - rcu_read_lock(); parent = rcu_dereference(ctx->parent_ctx); next_ctx = next->perf_event_ctxp; --