Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753450AbaG2NZF (ORCPT ); Tue, 29 Jul 2014 09:25:05 -0400 Received: from mail-oi0-f49.google.com ([209.85.218.49]:62097 "EHLO mail-oi0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750960AbaG2NZE (ORCPT ); Tue, 29 Jul 2014 09:25:04 -0400 X-Greylist: delayed 433 seconds by postgrey-1.27 at vger.kernel.org; Tue, 29 Jul 2014 09:25:04 EDT MIME-Version: 1.0 In-Reply-To: <20140729014343.GE5203@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> <20140729014343.GE5203@intel.com> From: Vincent Guittot Date: Tue, 29 Jul 2014 15:17:29 +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 29 July 2014 03:43, Yuyang Du wrote: > On Tue, Jul 29, 2014 at 11:12:37AM +0200, Vincent Guittot wrote: >> >> >> >> 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 >> > > Well, I see your point. But the problem is what matters is load_avg vs. load_avg, not a > load_avg itself. So, if load_avg1 discards old weight if weight is changed, but load_avg2 > has no weight changed or has weight changed, the comparison load_avg1 vs. load_avg2 is not > fair, but too impacted by the new weight. The point is, we count in history, so connt in the > real history, which is the whole point of why we count the history. Make sense? IIUC, you want to soften the impact of weight change on cfs_rq-> load_avg ? > > 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/