Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753256AbaG2JND (ORCPT ); Tue, 29 Jul 2014 05:13:03 -0400 Received: from mail-oi0-f53.google.com ([209.85.218.53]:61079 "EHLO mail-oi0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753240AbaG2JM7 (ORCPT ); Tue, 29 Jul 2014 05:12:59 -0400 MIME-Version: 1.0 In-Reply-To: <20140727173616.GA22986@intel.com> References: <1405639567-21445-1-git-send-email-yuyang.du@intel.com> <1405639567-21445-3-git-send-email-yuyang.du@intel.com> <20140727173616.GA22986@intel.com> From: Vincent Guittot Date: Tue, 29 Jul 2014 11:12:37 +0200 Message-ID: Subject: Re: [PATCH 2/2 v4] sched: Rewrite per entity runnable load average tracking To: Yuyang Du Cc: "mingo@redhat.com" , Peter Zijlstra , linux-kernel , Paul Turner , Benjamin Segall , arjan.van.de.ven@intel.com, Len Brown , rafael.j.wysocki@intel.com, alan.cox@intel.com, "Gross, Mark" , "fengguang.wu@intel.com" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27 July 2014 19:36, Yuyang Du wrote: > Hi Vincent, > > On Fri, Jul 18, 2014 at 11:43:00AM +0200, Vincent Guittot wrote: >> > @@ -2291,23 +2299,24 @@ static __always_inline int __update_entity_runnable_avg(u64 now, >> > delta >>= 10; >> > if (!delta) >> > return 0; >> > - sa->last_runnable_update = now; >> > + sa->last_update_time = now; >> > >> > /* delta_w is the amount already accumulated against our next period */ >> > - delta_w = sa->runnable_avg_period % 1024; >> > + delta_w = sa->period_contrib; >> > if (delta + delta_w >= 1024) { >> > - /* period roll-over */ >> > decayed = 1; >> > >> > + /* how much left for next period will start over, we don't know yet */ >> > + sa->period_contrib = 0; >> > + >> > /* >> > * Now that we know we're crossing a period boundary, figure >> > * out how much from delta we need to complete the current >> > * period and accrue it. >> > */ >> > delta_w = 1024 - delta_w; >> > - if (runnable) >> > - sa->runnable_avg_sum += delta_w; >> > - sa->runnable_avg_period += delta_w; >> > + if (w) >> > + sa->load_sum += w * delta_w; >> >> Do you really need to have *w for computing the load_sum ? can't you >> only use it when computing the load_avg ? >> >> sa->load_avg = div_u64(sa->load_sum * w , LOAD_AVG_MAX) >> > > For task, assuming its load.weight does not change much, yes, we can. But in theory, task's I would even say that the load_avg of a task should not be impacted by an old priority value. Once, the priority of a task is changed, we should only take into account this new priority to weight the load_avg of the task > load.weight can change, and *w in load_sum can take into that change. For group entity > and cfs_rq, its load.weight changes all the time, I don't know how to do it without *w > for load_sum. IMHO, we should apply the same policy than the one i mentioned for task. So the load_avg of an entity or a cfs_rq will not be disturbed by an old but no more valid weight Vincent > > Sorry for my irresponsiveness for last week. I was on vacation and unfortunately failed to > connect VPN from where I was. > > Thanks, > Yuyang -- 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/