From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758386AbdEAP41 (ORCPT ); Mon, 1 May 2017 11:56:27 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50288 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751223AbdEAP4X (ORCPT ); Mon, 1 May 2017 11:56:23 -0400 Date: Mon, 1 May 2017 17:56:13 +0200 From: Peter Zijlstra To: Tejun Heo Cc: Vincent Guittot , Ingo Molnar , linux-kernel , Linus Torvalds , Mike Galbraith , Paul Turner , Chris Mason , kernel-team@fb.com Subject: Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Message-ID: <20170501155613.plfee2hzfvt3n6j7@hirez.programming.kicks-ass.net> References: <20170424201344.GA14169@wtj.duckdns.org> <20170424201444.GC14169@wtj.duckdns.org> <20170426225202.GC11348@wtj.duckdns.org> <20170428203347.GC19364@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170428203347.GC19364@htj.duckdns.org> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 28, 2017 at 04:33:47PM -0400, Tejun Heo wrote: > I'm attaching the debug patch. With your change (avg instead of > runnable_avg), the following trace shows why it's wrong. Ah, OK. So you really want runnable_avg (and I understand why), which is rather unfortunate, since we have everything on load_avg. So for shares, load_avg gives a more stable number. This is important since tg->load_avg is a global number, so computing it is expensive (and slow). Therefore more stable numbers are good. > The thing with cfs_rq se's load_avg is that, it isn't really used > anywhere else AFAICS, so overriding it to the cfs_rq's > runnable_load_avg isn't prettiest but doesn't really change anything. You mean, consistently expressing a group's se->load.weight in terms of runnable_load_avg? See the above.