From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755488Ab0I1N5c (ORCPT ); Tue, 28 Sep 2010 09:57:32 -0400 Received: from mailout-de.gmx.net ([213.165.64.22]:37949 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1753230Ab0I1N5b (ORCPT ); Tue, 28 Sep 2010 09:57:31 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+QvJ0tfHuQjM5q6TuO1MsC0+uNwa3FMYGlFGKIfY Q/l4K7+GH4lvxV Subject: Re: [PATCH 0/3][RFC] Improve load balancing when tasks have large weight differential From: Mike Galbraith To: Nikhil Rao Cc: Ingo Molnar , Peter Zijlstra , Venkatesh Pallipadi , linux-kernel@vger.kernel.org In-Reply-To: <1285633798-26886-1-git-send-email-ncrao@google.com> References: <1285633798-26886-1-git-send-email-ncrao@google.com> Content-Type: text/plain Date: Tue, 28 Sep 2010 15:57:53 +0200 Message-Id: <1285682273.7469.3.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2010-09-27 at 17:29 -0700, Nikhil Rao wrote: > Hi all, > > I have attached a series of patches that improve load balancing when there is a > large weight differential between tasks. These patches are based off the > feedback Peter Zijlstra gave in an earlier post (see http://thread.gmane.org/gmane.linux.kernel/1015966). > They can be applied to v2.6.36-rc5 or -tip without conflicts. > > Tested with the following setup. > - Test machine is a 16 cpu box (quad-socket, quad-core). > - Baseline is v2.6.36-rc5 kernel > > We spawn 16 SCHED_IDLE soaker threads and one SCHED_NORMAL task. On the > baseline kernel, the machine has ~18% idle time. With these patches applied on > top of baseline, idle time drops to 0%. Hm. I can get it stuck with one core idle on ym little quad. top - 15:53:22 up 11 min, 17 users, load average: 5.05, 4.40, 2.51 Tasks: 270 total, 7 running, 263 sleeping, 0 stopped, 0 zombie Cpu(s): 75.3%us, 0.0%sy, 0.0%ni, 24.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND 7455 root 5 -15 7996 340 256 R 100 0.0 0:59.93 1 pert 7421 root 20 0 7996 340 256 R 50 0.0 4:20.01 3 pert 7422 root 20 0 7996 340 256 R 50 0.0 3:45.81 2 pert 7423 root 20 0 7996 340 256 R 50 0.0 4:09.45 2 pert 7424 root 20 0 7996 344 256 R 50 0.0 4:12.75 3 pert