From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 14 Oct 2002 04:30:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 14 Oct 2002 04:30:34 -0400 Received: from packet.digeo.com ([12.110.80.53]:53933 "EHLO packet.digeo.com") by vger.kernel.org with ESMTP id ; Mon, 14 Oct 2002 04:30:32 -0400 Message-ID: <3DAA8200.2AF20C5C@digeo.com> Date: Mon, 14 Oct 2002 01:36:16 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.5.42 i686) X-Accept-Language: en MIME-Version: 1.0 To: Joern Nettingsmeier CC: linux-audio-dev@music.columbia.edu, linux-kernel@vger.kernel.org Subject: Re: [linux-audio-dev] latency performance of 2.4 and 2.5... References: <3DA6C8A3.2892656@folkwang-hochschule.de> <3DAA7E8F.36B03682@folkwang-hochschule.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 14 Oct 2002 08:36:17.0395 (UTC) FILETIME=[C3805C30:01C2735C] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Joern Nettingsmeier wrote: > > some new interesting results with 2.5.42: > > http://spunk.dnsalias.org/latencytest/2.5.42/2x256.html > > overall much worse, *but* greatly reduced latency peaks (max. 6 ms) as > compared to 2.5.41: > > http://spunk.dnsalias.org/latencytest/2.5.41/2x256.html > > here the peaks easily reach 13 ms. Rather depends on the filesystem. ext3 does its own write scheduling, and does stuff inside lock_kernel(). It needs a couple of scheduling points I guess. I'd expect ext2 to work OK with preemption, but nobody has really looked yet. Unless you're using ftruncate() (grr.) > i'm not really sure what to make of this.... > can someone explain ? > > andrew, it seems part of your mm patch was merged - is there an updated > patch around that will add the missing hunks ? Well 2.5.41 had the big change to the truncate code, which was a rather important part of this whole effort. I can't immediately think of a 2.5.42 change which would do this... But nobody has really got down and dug out the toolkit on 2.5 scheduling latency. I guess I should do that soon.