Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753829AbaBYTzz (ORCPT ); Tue, 25 Feb 2014 14:55:55 -0500 Received: from mail-pb0-f54.google.com ([209.85.160.54]:33863 "EHLO mail-pb0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753330AbaBYTzx (ORCPT ); Tue, 25 Feb 2014 14:55:53 -0500 From: bsegall@google.com To: Dietmar Eggemann Cc: Srikar Dronamraju , Peter Zijlstra , "linux-kernel\@vger.kernel.org" , pjt@google.com Subject: Re: [PATCH] sched: put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED References: <1393328862-19997-1-git-send-email-dietmar.eggemann@arm.com> <20140225131642.GA3265@linux.vnet.ibm.com> <530CD71F.9030908@arm.com> Date: Tue, 25 Feb 2014 11:55:50 -0800 In-Reply-To: <530CD71F.9030908@arm.com> (Dietmar Eggemann's message of "Tue, 25 Feb 2014 17:47:11 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dietmar Eggemann writes: > On 25/02/14 13:16, Srikar Dronamraju wrote: >>> The struct sched_avg of struct rq is only used in case group >>> scheduling is enabled inside __update_tg_runnable_avg() to update >>> per-cpu representation of a task group. I.e. that there is no need to >>> maintain the runnable avg of a rq in the !CONFIG_FAIR_GROUP_SCHED case. >>> >>> This patch guards struct sched_avg of struct rq and >>> update_rq_runnable_avg() with CONFIG_FAIR_GROUP_SCHED. >>> Reviewed-by: Ben Segall If we ever decide to use runnable_avg_sum/period in balance or something, it's trivial enough to move it back, and there is no point in calculating unusued stats until then. >> >> While this patch looks good, I see fields in sched_avg viz decay_count, >> last_runnable_update, load_avg_contrib only relevant to sched_entity. >> i.e they don't seem to be updated or used for rq->avg. Should we look at >> splitting sched_avg so that rq->avg doesn't have unwanted fields? > > Yes, AFAICS at least load_avg_contrib and decay_count are only relevant > for struct sched_entity whereas last_runnable_update is used in > __update_entity_runnable_avg() itself. > > By having struct sched_avg embedded into struct sched_entity and struct > rq, __update_entity_runnable_avg() and __update_tg_runnable_avg() can be > used on both and moreover, all current members of struct sched_avg > belong logically together. > > With this patch I was more interested in the fact that we do not have to > maintain the load avg for struct rq in a !CONFIG_FAIR_GROUP_SCHED system. > Yeah, last_runnable_update and runnable_avg_sum/period are used, decay_count and load_avg_contrib could be moved to the se just fine, and won't cause any problems. -- 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/