From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162061AbcEaIeN (ORCPT ); Tue, 31 May 2016 04:34:13 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48008 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756476AbcEaIeK (ORCPT ); Tue, 31 May 2016 04:34:10 -0400 Date: Tue, 31 May 2016 10:34:02 +0200 From: Peter Zijlstra To: Yuyang Du Cc: 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 v2 1/3] sched/fair: Clean up attach_entity_load_avg() Message-ID: <20160531083402.GI3193@twins.programming.kicks-ass.net> References: <1464647577-23057-1-git-send-email-yuyang.du@intel.com> <1464647577-23057-2-git-send-email-yuyang.du@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1464647577-23057-2-git-send-email-yuyang.du@intel.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 31, 2016 at 06:32:54AM +0800, Yuyang Du wrote: > +++ b/kernel/sched/fair.c > @@ -2961,24 +2961,6 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg) > > static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) > { > - if (!sched_feat(ATTACH_AGE_LOAD)) > - goto skip_aging; > - > - /* > - * If we got migrated (either between CPUs or between cgroups) we'll > - * have aged the average right before clearing @last_update_time. > - */ > - if (se->avg.last_update_time) { > - __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)), > - &se->avg, 0, 0, NULL); > - > - /* > - * XXX: we could have just aged the entire load away if we've been > - * absent from the fair class for too long. > - */ > - } > - > -skip_aging: > se->avg.last_update_time = cfs_rq->avg.last_update_time; > cfs_rq->avg.load_avg += se->avg.load_avg; > cfs_rq->avg.load_sum += se->avg.load_sum; So I'm not a big fan of this patch; the aging is a conceptual part of attaching the load, the fact that it only happens in one callsite is a mere 'accident'. The other two patches look reasonable; but I'll wait until Vince has commented on them..