From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752277Ab1GUBAR (ORCPT ); Wed, 20 Jul 2011 21:00:17 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:48425 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751949Ab1GUBAP (ORCPT ); Wed, 20 Jul 2011 21:00:15 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1/DcidXYMrDBnP8nwIp8bP8tMrzfrbEA0LdfmTn2A vJR3vI9Yvpozs4 Subject: Re: sched: fix/optimise some issues From: Mike Galbraith To: Peter Zijlstra Cc: stephan.baerwolf@tu-ilmenau.de, linux-kernel@vger.kernel.org, Ingo Molnar , ncrao@google.com In-Reply-To: <1311189090.29152.73.camel@twins> References: <4E26DB41.9070002@tu-ilmenau.de> <1311189090.29152.73.camel@twins> Content-Type: text/plain; charset="UTF-8" Date: Thu, 21 Jul 2011 03:00:09 +0200 Message-ID: <1311210009.7746.37.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 8bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-07-20 at 21:11 +0200, Peter Zijlstra wrote: > On Wed, 2011-07-20 at 15:42 +0200, Stephan Bärwolf wrote: > > In "check_preempt_tick()" (kernel/sched_fair.c:1093) a ulong > > called "ideal_runtime" stores a timeslice of the current task > > (scheduling entity). This time complies real cpu-time. > > > > At the end of the same function (nr_running > 1) this (real) time > > is compared with a virtual-runtime-delta. Obviously the timeunits > > (real vs. virtual) didn't fit. > > > > Using "wakeup_preempt_entity()" instead should fix this in a even > > more general way. (That's what I thought at first too) > Hrm,. I'm fairly sure we did that on purpose and the thing that is > missing is a big fat comment. People keep trying to fix that (me > included). > > I'll try and dig up the why and such. Better to just kill it outright. It's not doing that much anyway. -Mike