From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030341AbWD1JfT (ORCPT ); Fri, 28 Apr 2006 05:35:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030342AbWD1JfS (ORCPT ); Fri, 28 Apr 2006 05:35:18 -0400 Received: from mail.gmx.de ([213.165.64.20]:51861 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1030341AbWD1JfR (ORCPT ); Fri, 28 Apr 2006 05:35:17 -0400 X-Authenticated: #14349625 Subject: Re: [ckrm-tech] Re: [PATCH 0/9] CPU controller From: Mike Galbraith To: Kirill Korotaev Cc: MAEDA Naoaki , akpm@osdl.org, linux-kernel@vger.kernel.org, ckrm-tech@lists.sourceforge.net In-Reply-To: <4451CEB7.6080509@sw.ru> References: <20060428013730.9582.9351.sendpatchset@moscone.dvs.cs.fujitsu.co.jp> <1146201936.7523.15.camel@homer> <4451AEA4.1040108@sw.ru> <1146208288.7551.19.camel@homer> <1146210395.7551.37.camel@homer> <4451CEB7.6080509@sw.ru> Content-Type: text/plain Date: Fri, 28 Apr 2006 11:35:06 +0200 Message-Id: <1146216906.8067.18.camel@homer> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2006-04-28 at 12:13 +0400, Kirill Korotaev wrote: > >>>I'm also pretty sure, that CPU controller based on timeslice tricks > >>>behaves poorly on burstable load patterns as well and with interactive > >>>tasks. So before commiting I propose to perform a good testing on > >>>different load patterns. > >> > >>Yes, it can only react very slowly. > > > > > > Actually, this might not be that much of a problem. I know I can > > traverse queue heads periodically very cheaply. Traversing both active > > and expired arrays to requeue starving tasks once every 100ms costs max > > 4usecs (3GHz P4) for a typical distribution. > > with fair scheduling with can be a big problem, as tasks working less > then a tick are hard to account :/ Yeah, tasks dodging the timer interrupt can steal considerable time. I instrumented this once, and caught tasks stealing in excess of 30% of the timeslice of their more lethargic brothers. Generally, they get caught often enough that statistics ~evens the playing field. -Mike