From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752030AbcFNLid (ORCPT ); Tue, 14 Jun 2016 07:38:33 -0400 Received: from mail-wm0-f46.google.com ([74.125.82.46]:36929 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751665AbcFNLib (ORCPT ); Tue, 14 Jun 2016 07:38:31 -0400 Date: Tue, 14 Jun 2016 12:38:28 +0100 From: Matt Fleming To: Yuyang Du Cc: peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org, bsegall@google.com, pjt@google.com, morten.rasmussen@arm.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com Subject: Re: [PATCH v5 4/5] sched/fair: Skip detach sched avgs for new task when changing task groups Message-ID: <20160614113828.GH2658@codeblueprint.co.uk> References: <1465427754-28897-1-git-send-email-yuyang.du@intel.com> <1465427754-28897-5-git-send-email-yuyang.du@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1465427754-28897-5-git-send-email-yuyang.du@intel.com> User-Agent: Mutt/1.5.24+41 (02bc14ed1569) (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 09 Jun, at 07:15:53AM, Yuyang Du wrote: > Newly forked task has not been enqueued, so should not be removed from > cfs_rq in task_move_group_fair(). To do so, we identify newly forked > tasks by their sched_avg's last_update_time in detach_entity_load_avg(). > > Signed-off-by: Yuyang Du > --- > kernel/sched/fair.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 6e870c6..e0f219b 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -2943,6 +2943,10 @@ static inline void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_en > > static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) > { > + /* Newly forked tasks are not attached yet. */ > + if (!se->avg.last_update_time) > + return; > + Now that we no longer have the @fork parameter to provide context, this comment would benefit from some expansion. What about something like this, /* * Newly forked tasks that are being moved between groups * haven't been enqueued anywhere yet, and don't need detaching. */ ?