From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932207AbcJZLpc (ORCPT ); Wed, 26 Oct 2016 07:45:32 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:56037 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755153AbcJZLp3 (ORCPT ); Wed, 26 Oct 2016 07:45:29 -0400 Date: Wed, 26 Oct 2016 13:45:22 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com, yuyang.du@intel.com, Morten.Rasmussen@arm.com, linaro-kernel@lists.linaro.org, pjt@google.com, bsegall@google.com, kernellwp@gmail.com Subject: Re: [PATCH 4/6 v5] sched: propagate load during synchronous attach/detach Message-ID: <20161026114522.GH3102@twins.programming.kicks-ass.net> References: <1476695653-12309-1-git-send-email-vincent.guittot@linaro.org> <1476695653-12309-5-git-send-email-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1476695653-12309-5-git-send-email-vincent.guittot@linaro.org> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 17, 2016 at 11:14:11AM +0200, Vincent Guittot wrote: > +/* Take into account change of load of a child task group */ > +static inline void > +update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se) > +{ > + struct cfs_rq *gcfs_rq = group_cfs_rq(se); > + long delta, load = gcfs_rq->avg.load_avg; > + > + /* > + * If the load of group cfs_rq is null, the load of the > + * sched_entity will also be null so we can skip the formula > + */ Does it make sense to do: if (!load) goto no_load; and avoid the indent? > + if (load) { > + long tg_load; > + > + /* Get tg's load and ensure tg_load > 0 */ > + tg_load = atomic_long_read(&gcfs_rq->tg->load_avg) + 1; > + > + /* Ensure tg_load >= load and updated with current load*/ > + tg_load -= gcfs_rq->tg_load_avg_contrib; > + tg_load += load; > + > + /* > + * We need to compute a correction term in the case that the > + * task group is consuming more cpu than a task of equal > + * weight. A task with a weight equals to tg->shares will have > + * a load less or equal to scale_load_down(tg->shares). + * > + * Similarly, the sched_entities that represent the task group > + * at parent level, can't have a load higher than > + * scale_load_down(tg->shares). And the Sum of sched_entities' > + * load must be <= scale_load_down(tg->shares). > + */ > + if (tg_load > scale_load_down(gcfs_rq->tg->shares)) { > + /* scale gcfs_rq's load into tg's shares*/ > + load *= scale_load_down(gcfs_rq->tg->shares); > + load /= tg_load; > + } > + } > + no_load: > + delta = load - se->avg.load_avg; > + > + /* Nothing to update */ > + if (!delta) > + return; > + > + /* Set new sched_entity's load */ > + se->avg.load_avg = load; > + se->avg.load_sum = se->avg.load_avg * LOAD_AVG_MAX; > + > + /* Update parent cfs_rq load */ > + add_positive(&cfs_rq->avg.load_avg, delta); > + cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * LOAD_AVG_MAX; > + > + /* > + * If the sched_entity is already enqueued, we also have to update the > + * runnable load avg. > + */ > + if (se->on_rq) { > + /* Update parent cfs_rq runnable_load_avg */ > + add_positive(&cfs_rq->runnable_load_avg, delta); > + cfs_rq->runnable_load_sum = cfs_rq->runnable_load_avg * LOAD_AVG_MAX; > + } > +}