From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754462AbZGJOuK (ORCPT ); Fri, 10 Jul 2009 10:50:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753907AbZGJOt7 (ORCPT ); Fri, 10 Jul 2009 10:49:59 -0400 Received: from ey-out-1920.google.com ([74.125.78.145]:64965 "EHLO ey-out-1920.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753838AbZGJOt7 (ORCPT ); Fri, 10 Jul 2009 10:49:59 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=uXtcBgG8KB8km5Unb5tgxR4k+AiK6kXxCVea2vC9NDMsnrrCimhe5aoMKG2Y8dLfmC ZZPBLRECWCDOM5cA5mlceiGyQPaiRJSSo2qcxFzgwdV/hFIEWK+siYz30zgkPA2wdX/H dyxn7n0yXW2meyjn9HRSuk6++bSHSOMW32yV8= From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Frederic Weisbecker , Peter Zijlstra Subject: [PATCH 1/2] sched: Drop the need_resched() loop from cond_resched() Date: Fri, 10 Jul 2009 16:49:50 +0200 Message-Id: <1247237391-5352-1-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.6.2.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Peter Zijlstra --- kernel/sched.c | 8 +++----- 1 files changed, 3 insertions(+), 5 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 4d1e387..87ecac1 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6613,11 +6613,9 @@ 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) -- 1.6.2.3