From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752407Ab1ADPMJ (ORCPT ); Tue, 4 Jan 2011 10:12:09 -0500 Received: from casper.infradead.org ([85.118.1.10]:59931 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752221Ab1ADPMH (ORCPT ); Tue, 4 Jan 2011 10:12:07 -0500 Message-Id: <20110104150102.911325900@chello.nl> User-Agent: quilt/0.48-1 Date: Tue, 04 Jan 2011 15:59:41 +0100 From: Peter Zijlstra To: Chris Mason , Frank Rowand , Ingo Molnar , Thomas Gleixner , Mike Galbraith , Oleg Nesterov , Paul Turner , Jens Axboe , Yong Zhang Cc: linux-kernel@vger.kernel.org, Peter Zijlstra Subject: [RFC][PATCH 12/18] sched: Drop rq->lock from first part of wake_up_new_task() References: <20110104145929.772813816@chello.nl> Content-Disposition: inline; filename=sched-wunt.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since p->pi_lock now protects all things needed to call select_task_rq() avoid the double remote rq->lock acquisition and rely on p->pi_lock. Signed-off-by: Peter Zijlstra --- kernel/sched.c | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-) Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -2681,28 +2681,18 @@ void wake_up_new_task(struct task_struct { unsigned long flags; struct rq *rq; - int cpu __maybe_unused = get_cpu(); + raw_spin_lock_irqsave(&p->pi_lock, flags); #ifdef CONFIG_SMP - rq = task_rq_lock(p, &flags); - p->state = TASK_WAKING; - /* * Fork balancing, do it here and not earlier because: * - cpus_allowed can change in the fork path * - any previously selected cpu might disappear through hotplug - * - * We set TASK_WAKING so that select_task_rq() can drop rq->lock - * without people poking at ->cpus_allowed. */ - cpu = select_task_rq(p, SD_BALANCE_FORK, 0); - set_task_cpu(p, cpu); - - p->state = TASK_RUNNING; - task_rq_unlock(rq, &flags); + set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0)); #endif - rq = task_rq_lock(p, &flags); + rq = __task_rq_lock(p); activate_task(rq, p, 0); trace_sched_wakeup_new(p, true); check_preempt_curr(rq, p, WF_FORK); @@ -2710,8 +2700,8 @@ void wake_up_new_task(struct task_struct if (p->sched_class->task_woken) p->sched_class->task_woken(rq, p); #endif - task_rq_unlock(rq, &flags); - put_cpu(); + __task_rq_unlock(rq); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); } #ifdef CONFIG_PREEMPT_NOTIFIERS