From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758400AbYEVUC7 (ORCPT ); Thu, 22 May 2008 16:02:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757611AbYEVUCn (ORCPT ); Thu, 22 May 2008 16:02:43 -0400 Received: from zcars04f.nortel.com ([47.129.242.57]:60850 "EHLO zcars04f.nortel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757006AbYEVUCm (ORCPT ); Thu, 22 May 2008 16:02:42 -0400 Message-ID: <4835D14B.20904@nortel.com> Date: Thu, 22 May 2008 14:02:19 -0600 From: "Chris Friesen" User-Agent: Mozilla Thunderbird 1.0.2-6 (X11/20050513) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Peter Zijlstra CC: linux-kernel@vger.kernel.org, vatsa@linux.vnet.ibm.com, mingo@elte.hu, pj@sgi.com Subject: Re: fair group scheduler not so fair? References: <4834B75A.40900@nortel.com> <1211439417.29104.7.camel@twins> In-Reply-To: <1211439417.29104.7.camel@twins> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 22 May 2008 20:02:23.0490 (UTC) FILETIME=[BFFE3620:01C8BC46] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra wrote: > Could you see if the patches found here: > > http://programming.kicks-ass.net/kernel-patches/sched-smp-group-fixes/ > > make any difference for you? Not much difference. In the following case pid 2438 is in group "a" and pids 2439/2440 are in group "b". Pid 2438 still gets stuck with only 66%. 2439 cfriesen 20 0 3800 392 336 R 99.7 0.0 3:17.37 cat 2438 cfriesen 20 0 3800 392 336 R 66.2 0.0 2:33.63 cat 2440 cfriesen 20 0 3800 392 336 R 33.6 0.0 1:47.53 cat With 3 tasks in group a, 2 in group b, it's still pretty poor: 2514 cfriesen 20 0 3800 392 336 R 52.5 0.0 0:48.11 cat 2515 cfriesen 20 0 3800 392 336 R 50.2 0.0 0:42.53 cat 2439 cfriesen 20 0 3800 392 336 R 35.4 0.0 4:37.07 cat 2438 cfriesen 20 0 3800 392 336 R 33.3 0.0 3:34.97 cat 2440 cfriesen 20 0 3800 392 336 R 28.3 0.0 2:26.17 cat If I boot with "nosmp" it behaves more or less as expected: 3 tasks in default: 2427 cfriesen 20 0 3800 392 336 R 33.7 0.0 0:36.54 cat 2429 cfriesen 20 0 3800 392 336 R 33.5 0.0 0:35.63 cat 2428 cfriesen 20 0 3800 392 336 R 32.9 0.0 0:35.84 cat 1 task in a, 2 in b: 2427 cfriesen 20 0 3800 392 336 R 49.8 0.0 1:45.74 cat 2428 cfriesen 20 0 3800 392 336 R 25.0 0.0 1:38.65 cat 2429 cfriesen 20 0 3800 392 336 R 25.0 0.0 1:38.18 cat 3 tasks in a, 2 in b: 2521 cfriesen 20 0 3800 392 336 R 25.2 0.0 0:08.52 cat 2522 cfriesen 20 0 3800 392 336 R 25.2 0.0 0:08.23 cat 2427 cfriesen 20 0 3800 392 336 R 16.6 0.0 1:59.39 cat 2429 cfriesen 20 0 3800 392 336 R 16.6 0.0 1:47.63 cat 2428 cfriesen 20 0 3800 392 336 R 16.4 0.0 1:48.65 cat I haven't really dug into the scheduler yet (although that's next), but based on these results it doesn't really look like the load balancer is properly group-aware. Chris