From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752527AbZGROWR (ORCPT ); Sat, 18 Jul 2009 10:22:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752477AbZGROWQ (ORCPT ); Sat, 18 Jul 2009 10:22:16 -0400 Received: from hera.kernel.org ([140.211.167.34]:53888 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752408AbZGROWP (ORCPT ); Sat, 18 Jul 2009 10:22:15 -0400 Date: Sat, 18 Jul 2009 14:21:31 GMT From: tip-bot for Frederic Weisbecker To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, fweisbec@gmail.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, fweisbec@gmail.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1247725694-6082-1-git-send-email-fweisbec@gmail.com> References: <1247725694-6082-1-git-send-email-fweisbec@gmail.com> Subject: [tip:sched/core] sched: Drop the need_resched() loop from cond_resched() Message-ID: Git-Commit-ID: e7aaaa6934636d7a6cadd9e2a05250fbb6a34f65 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]); Sat, 18 Jul 2009 14:21:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: e7aaaa6934636d7a6cadd9e2a05250fbb6a34f65 Gitweb: http://git.kernel.org/tip/e7aaaa6934636d7a6cadd9e2a05250fbb6a34f65 Author: Frederic Weisbecker AuthorDate: Thu, 16 Jul 2009 15:44:29 +0200 Committer: Ingo Molnar CommitDate: Sat, 18 Jul 2009 15:51:38 +0200 sched: Drop the need_resched() loop from cond_resched() The schedule() function is a loop that reschedules the current task while the TIF_NEED_RESCHED flag is set: void schedule(void) { need_resched: /* schedule code */ if (need_resched()) goto need_resched; } And cond_resched() repeat this loop: do { add_preempt_count(PREEMPT_ACTIVE); schedule(); sub_preempt_count(PREEMPT_ACTIVE); } while(need_resched()); This loop is needless because schedule() already did the check and nothing can set TIF_NEED_RESCHED between schedule() exit and the loop check in need_resched(). Then remove this needless loop. Signed-off-by: Frederic Weisbecker Acked-by: Peter Zijlstra Signed-off-by: Peter Zijlstra LKML-Reference: <1247725694-6082-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/sched.c | 8 +++----- 1 files changed, 3 insertions(+), 5 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 03f7e3f..4c5ee84 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6618,11 +6618,9 @@ static void __cond_resched(void) * PREEMPT_ACTIVE, which could trigger a second * cond_resched() call. */ - do { - add_preempt_count(PREEMPT_ACTIVE); - schedule(); - sub_preempt_count(PREEMPT_ACTIVE); - } while (need_resched()); + add_preempt_count(PREEMPT_ACTIVE); + schedule(); + sub_preempt_count(PREEMPT_ACTIVE); } int __sched _cond_resched(void)