From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758872Ab2FUIl5 (ORCPT ); Thu, 21 Jun 2012 04:41:57 -0400 Received: from casper.infradead.org ([85.118.1.10]:45766 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758838Ab2FUIly convert rfc822-to-8bit (ORCPT ); Thu, 21 Jun 2012 04:41:54 -0400 Message-ID: <1340268104.21745.159.camel@twins> Subject: Re: [RFC][PATCH 2/4] sched: Push put_prev_task() into pick_next_task() From: Peter Zijlstra To: Michael Wang Cc: mingo@kernel.org, pjt@google.com, venki@google.com, efault@gmx.de, rostedt@goodmis.org, glommer@parallels.com, linux-kernel@vger.kernel.org Date: Thu, 21 Jun 2012 10:41:44 +0200 In-Reply-To: <4FE2CEB0.7080200@linux.vnet.ibm.com> References: <20120614132902.800827488@chello.nl> <20120614133212.690691207@chello.nl> <4FE2CEB0.7080200@linux.vnet.ibm.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-06-21 at 15:35 +0800, Michael Wang wrote: > > +pick_next_task_fair(struct rq *rq, struct task_struct *prev) > > { > > struct task_struct *p; > > struct cfs_rq *cfs_rq = &rq->cfs; > > @@ -2999,6 +3000,9 @@ static struct task_struct *pick_next_tas > > if (!cfs_rq->nr_running) > > return NULL; > > > > + if (prev) > > + prev->sched_class->put_prev_task(rq, prev); > > + > > do { > > se = pick_next_entity(cfs_rq); > > set_next_entity(cfs_rq, se); > > --- a/kernel/sched/idle_task.c > > +++ b/kernel/sched/idle_task.c > > @@ -22,8 +22,12 @@ static void check_preempt_curr_idle(stru > > resched_task(rq->idle); > > } > > Will it cause trouble when the last task on cfs_rq was dequeued before > been putted? > > The cfs_rq->nr_running will be 0 and we will miss the chance to put > prev, will we? pick_next_task_idle() will then do the put, no?