From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753855Ab2DRSdB (ORCPT ); Wed, 18 Apr 2012 14:33:01 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:33536 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751537Ab2DRSc6 (ORCPT ); Wed, 18 Apr 2012 14:32:58 -0400 X-Authority-Analysis: v=2.0 cv=IaEFqBWa c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=JomeGkWH5N8A:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=NXGx4cpFtuKCEL7X5GYA:9 a=PUjeQqilurYA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-ID: <1334773976.28106.49.camel@gandalf.stny.rr.com> Subject: Re: [sched/rt] Optimization of function pull_rt_task() From: Steven Rostedt To: Kirill Tkhai Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra Date: Wed, 18 Apr 2012 14:32:56 -0400 In-Reply-To: <1334592379.28106.4.camel@gandalf.stny.rr.com> References: <1334519122.8698.3.camel@hp> <1334592379.28106.4.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.2.2-1 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-04-16 at 12:06 -0400, Steven Rostedt wrote: > On Sun, 2012-04-15 at 23:45 +0400, Kirill Tkhai wrote: > > The condition (src_rq->rt.rt_nr_running) is weak because it doesn't > > consider the cases when src_rq has only processes bound to it (when > > single cpu is allowed). It may be running kernel thread like > > migration/x etc. > > > > So it's better to use more stronger condition which is able to exclude > > above conditions. The function has_pushable_tasks() complitely does > > this. A task may be pullable for another cpu rq only if he is pushable > > for his own queue. > > I considered this before, and for some reason I never did the change. > I'll have to think about it. It seems like this would be the obvious > case, but I think there was something not so obvious that caused issues. > But I don't remember what it was. > > I'll have to rethink this again. I can't find anything wrong with this change. Maybe things change, or I was thinking of another change. I'll apply it and start running my tests against it. Thanks! -- Steve