Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755019Ab3EFPai (ORCPT ); Mon, 6 May 2013 11:30:38 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49929 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754582Ab3EFPag (ORCPT ); Mon, 6 May 2013 11:30:36 -0400 Date: Mon, 6 May 2013 17:28:50 +0200 From: Peter Zijlstra To: Alex Shi Cc: Paul Turner , Ingo Molnar , Thomas Gleixner , Andrew Morton , Borislav Petkov , Namhyung Kim , Mike Galbraith , Morten Rasmussen , Vincent Guittot , Preeti U Murthy , Viresh Kumar , LKML , Mel Gorman , Rik van Riel , Michael Wang Subject: Re: [PATCH v5 3/7] sched: set initial value of runnable avg for new forked task Message-ID: <20130506152850.GA17623@dyad.programming.kicks-ass.net> References: <1367804711-30308-1-git-send-email-alex.shi@intel.com> <1367804711-30308-4-git-send-email-alex.shi@intel.com> <5187760D.8060900@intel.com> <5187CB8E.6090303@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5187CB8E.6090303@intel.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1340 Lines: 28 On Mon, May 06, 2013 at 11:26:06PM +0800, Alex Shi wrote: > On 05/06/2013 06:22 PM, Paul Turner wrote: > >>> >> This is missing a scale_load() right? Further: Why not put this in > >>> >> __sched_fork? > >> > > >> > scale_load is not working now. Anyway I can add this. > > I believe someone tracked down a plausible cause for this: > > A governor was examining the values and making a mess with the scaled > > ones. I'm sorry, I don't have the post off hand. > > > > You actually likely ideally want this _on_ for these patches; the > > available resolution with SCHED_LOAD_SHIFT=10 disappears really > > quickly and scaling by runnable_avg only further accelerates that. > > Sorry for can not follow you. Do you mean the scaling by runnable_avg is > better than scale_load? > > In fact, after think twice of scale_load, guess better to figure out a > good usage for it before enabling blindly. He's saying its way too easy to run out of fractional bits with the current setup; adding the 10 extra fractional bits provided by SCHED_LOAD_SHIFT is advantagous and we should re-enable that. -- 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/