Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756270Ab3CSOVL (ORCPT ); Tue, 19 Mar 2013 10:21:11 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:54871 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755134Ab3CSOVJ (ORCPT ); Tue, 19 Mar 2013 10:21:09 -0400 Message-ID: <1363702857.22553.50.camel@laptop> Subject: Re: [PATCH 3/8] sched: don't consider other cpus in our group in case of NEWLY_IDLE From: Peter Zijlstra To: Joonsoo Kim Cc: Ingo Molnar , Srivatsa Vaddagiri , linux-kernel@vger.kernel.org Date: Tue, 19 Mar 2013 15:20:57 +0100 In-Reply-To: <1360820921-2513-4-git-send-email-iamjoonsoo.kim@lge.com> References: <1360820921-2513-1-git-send-email-iamjoonsoo.kim@lge.com> <1360820921-2513-4-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1886 Lines: 51 On Thu, 2013-02-14 at 14:48 +0900, Joonsoo Kim wrote: > Commit 88b8dac0 makes load_balance() consider other cpus in its group, > regardless of idle type. When we do NEWLY_IDLE balancing, we should not > consider it, because a motivation of NEWLY_IDLE balancing is to turn > this cpu to non idle state if needed. This is not the case of other cpus. > So, change code not to consider other cpus for NEWLY_IDLE balancing. > > With this patch, assign 'if (pulled_task) this_rq->idle_stamp = 0' > in idle_balance() is corrected, because NEWLY_IDLE balancing doesn't > consider other cpus. Assigning to 'this_rq->idle_stamp' is now valid. > > Cc: Srivatsa Vaddagiri > Signed-off-by: Joonsoo Kim Fair enough, good catch. Acked-by: Peter Zijlstra > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 0c6aaf6..97498f4 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5016,8 +5016,15 @@ static int load_balance(int this_cpu, struct rq *this_rq, > .cpus = cpus, > }; > > + /* For NEWLY_IDLE load_balancing, we don't need to consider > + * other cpus in our group */ > + if (idle == CPU_NEWLY_IDLE) { > + env.dst_grpmask = NULL; > + max_lb_iterations = 0; Just a small nit; I don't think we'll ever get to evaluate max_lb_iterations when !dst_grpmask. So strictly speaking its superfluous to touch it. > + } else { > + max_lb_iterations = cpumask_weight(env.dst_grpmask); > + } > cpumask_copy(cpus, cpu_active_mask); > - max_lb_iterations = cpumask_weight(env.dst_grpmask); > > schedstat_inc(sd, lb_count[idle]); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/