From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S275258AbTHGKHF (ORCPT ); Thu, 7 Aug 2003 06:07:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S275257AbTHGKHE (ORCPT ); Thu, 7 Aug 2003 06:07:04 -0400 Received: from dyn-ctb-203-221-72-79.webone.com.au ([203.221.72.79]:35338 "EHLO chimp.local.net") by vger.kernel.org with ESMTP id S275286AbTHGKFa (ORCPT ); Thu, 7 Aug 2003 06:05:30 -0400 Message-ID: <3F322463.6030708@cyberone.com.au> Date: Thu, 07 Aug 2003 20:05:23 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3.1) Gecko/20030618 Debian/1.3.1-3 X-Accept-Language: en MIME-Version: 1.0 To: Con Kolivas CC: linux-kernel@vger.kernel.org Subject: Re: 2.6.0-test2-mm3 osdl-aim-7 regression References: <200308061910.h76JAYw16323@mail.osdl.org> <200308071541.06091.kernel@kolivas.org> <3F320D15.7020403@cyberone.com.au> <200308072001.13740.kernel@kolivas.org> In-Reply-To: <200308072001.13740.kernel@kolivas.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Con Kolivas wrote: >On Thu, 7 Aug 2003 18:25, Nick Piggin wrote: > >>>The more frequently you round robin the lower the scheduler latency >>>between SCHED_OTHER tasks of the same priority. However, the longer the >>>timeslice the more benefit you get from cpu cache. Where is the sweet >>>spot? Depends on the hardware and your usage requirements of course, but >>>Ingo has empirically chosen 25ms after 50ms seemed too long. Basically >>>cache trashing becomes a real problem with timeslices below ~7ms on >>>modern hardware in my limited testing. A minor quirk in Ingo's original >>>code means _occasionally_ a task will be requeued with <3ms to go. It >>>will be interesting to see if fixing this (which O12.2+ does) makes a big >>>difference or whether we need to reconsider how frequently (if at all) we >>>round robin tasks. >>> >>Why not have it dynamic? CPU hogs get longer timeslices (but of course >>can be preempted by higher priorities). >> > >Funny you should say that. Before Ingo merged his A3 changes, that's what my >version of them did. > > Between you and me, I think this would be the right way to go if it could be done right. I don't think wli, mjb and the rest of their clique appreciate the 25ms reschedule!