From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755720AbYE3KMl (ORCPT ); Fri, 30 May 2008 06:12:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751819AbYE3KMd (ORCPT ); Fri, 30 May 2008 06:12:33 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:37540 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750764AbYE3KMc (ORCPT ); Fri, 30 May 2008 06:12:32 -0400 Date: Fri, 30 May 2008 15:51:21 +0530 From: Srivatsa Vaddagiri To: Dhaval Giani Cc: Chris Friesen , linux-kernel@vger.kernel.org, mingo@elte.hu, a.p.zijlstra@chello.nl, pj@sgi.com, Balbir Singh , aneesh.kumar@linux.vnet.ibm.com Subject: Re: fair group scheduler not so fair? Message-ID: <20080530102121.GG12836@linux.vnet.ibm.com> Reply-To: vatsa@linux.vnet.ibm.com References: <4834B75A.40900@nortel.com> <20080527171528.GD30285@linux.vnet.ibm.com> <483C4F5A.2010104@nortel.com> <20080528163318.GG30285@linux.vnet.ibm.com> <483DA5E7.5050600@nortel.com> <20080529164607.GC12836@linux.vnet.ibm.com> <483F207D.4010908@nortel.com> <20080530064324.GA29381@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080530064324.GA29381@linux.vnet.ibm.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 30, 2008 at 12:13:24PM +0530, Dhaval Giani wrote: > > Also, although the long-term results are good, the shorter-term fairness > > isn't great. Is there a tuneable that would allow for a tradeoff between > > performance and fairness? I have people that are looking for within 4% > > fairness over a 1sec interval. > > > > How fair does smp fairness look for a !group scenario? I don't expect > group schould be able to do much better. Just tested this combo for !group case: 1 nice0 (weight = 1024) 2 nice3 (each weight = 526) 3 nice5 (each weight = 335) You'd expect nice0 to get (on a 2 cpu system): 2 * 1024 / (1024 + 2*526 + 3*335) = 66.47 This is what I see over a 10sec interval (error = 6%): 4386 root 20 0 1384 228 176 R 60.4 0.0 3:06.75 1 nice0 4387 root 23 3 1384 232 176 R 37.9 0.0 1:57.03 0 nice3 4388 root 23 3 1384 228 176 R 37.9 0.0 1:57.24 0 nice3 4390 root 25 5 1384 228 176 R 24.1 0.0 1:14.62 0 nice5 4391 root 25 5 1384 228 176 R 19.8 0.0 1:01.26 1 nice5 4389 root 25 5 1384 228 176 R 19.7 0.0 1:01.12 1 nice5 Over 120sec interval (error still as high as 6%): 4386 root 20 0 1384 228 176 R 60.4 0.0 6:13.95 1 nice0 4388 root 23 3 1384 228 176 R 37.9 0.0 3:54.69 0 nice3 4387 root 23 3 1384 232 176 R 37.9 0.0 3:54.44 0 nice3 4390 root 25 5 1384 228 176 R 24.2 0.0 2:29.45 0 nice5 4391 root 25 5 1384 228 176 R 19.8 0.0 2:02.56 1 nice5 4389 root 25 5 1384 228 176 R 19.8 0.0 2:02.44 1 nice5 The high error could be because of interference from other tasks. Anyway I dont think !group case is better at achieving fairness over shorter intervals. -- Regards, vatsa