From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 18 Sep 2001 14:23:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 18 Sep 2001 14:23:05 -0400 Received: from mailg.telia.com ([194.22.194.26]:10456 "EHLO mailg.telia.com") by vger.kernel.org with ESMTP id ; Tue, 18 Sep 2001 14:22:55 -0400 Message-Id: <200109181822.f8IIMv618968@mailg.telia.com> Content-Type: text/plain; charset="iso-8859-1" From: Roger Larsson To: Dieter =?iso-8859-1?q?N=FCtzel?= , Linux Kernel List Subject: Re: Feedback on preemptible kernel patch Date: Tue, 18 Sep 2001 20:18:10 +0200 X-Mailer: KMail [version 1.3] In-Reply-To: <200109140302.f8E32LG13400@zero.tech9.net> <1000530869.32365.21.camel@phantasy> <20010918040550Z273827-761+10122@vger.kernel.org> In-Reply-To: <20010918040550Z273827-761+10122@vger.kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday den 18 September 2001 06:06, Dieter Nützel wrote: > Yes, but no crash or oops for me. > "Only" some "stalls" during MPEG/Ogg-Vorbis playback (2-5 sec) :-( > > > But I get some hiccup during noatun (mp3, ogg, etc. player for KDE-2.2) > > > or plaympeg together with dbench (16, 32). ReiserFS needs some > > > preemption fixes, too? > > > > You may still get some small hiccups ( < 1 second?) even with the > > preemption patch, as kernel locks prevent preemption (the patch can't > > guarentee low latency, just preemption outside of the locks). > > Sadly 2-5 seconds at the beginning of dbench and during bonnie++ block > operations (huge IO pressure, ~20% system, 3-5% user, 116308 kilobytes > paged out). > > > However, how bad was the hiccups with preemption disabled? I have heard > > reports where it is 3-5sec at times. > > Yes, nearly the same. > Do you run with the playback process reniced -N? It should really run with a low SCHED_FIFO or SCHED_RT policy. But renicing it with a negative value gives some of the benefits... (but you need to run as root) In addition to this the program might need to lock its pages down - the only thing I can think of that could cause several seconds delay would be if it has been swapped out... /RogerL -- Roger Larsson Skellefteå Sweden