From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 21 Sep 2001 12:31:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 21 Sep 2001 12:31:21 -0400 Received: from zapfhahn.bone.twc.de ([193.158.34.194]:25616 "EHLO zapfhahn.bone.twc.de") by vger.kernel.org with ESMTP id ; Fri, 21 Sep 2001 12:31:08 -0400 Message-ID: <20010921181800.36609@space.twc.de> Date: Fri, 21 Sep 2001 18:18:00 +0200 From: Stefan Westerfeld To: Roger Larsson Cc: Oliver Xymoron , =?iso-8859-1?Q?Dieter_N=FCtzel?= , Robert Love , Andrea Arcangeli , linux-kernel , ReiserFS List Subject: Re: [PATCH] Preemption Latency Measurement Tool In-Reply-To: <200109210047.f8L0lkv26045@maile.telia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.85e In-Reply-To: <200109210047.f8L0lkv26045@maile.telia.com>; from Roger Larsson on Fri, Sep 21, 2001 at 02:42:56AM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! On Fri, Sep 21, 2001 at 02:42:56AM +0200, Roger Larsson wrote: > > You might try stracing artsd to see if it hangs at a particular syscall. > > Use -tt or -r for timestamps and pipe the output through tee (to a file on > > your ramfs). > > I tried playing a mp3 with noatun via artsd. Starting dbench 32 I get the > same kind of dropouts - and no indication with my latency profiling patch => > no process with higher prio is waiting to run! > > One of noatun or artsd is waiting for something else! (That is why I included > Stefan Westerfeld... artsd) > > I noticed very nice improvement then reniceing (all) artsd and noatun. > (I did also change the buffer size in artsd down to 40 ms) > > (This part most for Stefan... > So I thought - lets try to run artsd with RT prio - changed the option > HOW can it get RT prio when it is not suid? I guess it can not... > > So I manually added suid bit - but then noatun could not connect with > artsd... bug?, backed out the suid change... but is behaves as it works, > could be that it has so short bursts that prio never get a chance to drop) If you want to run artsd with RT prio, add suid root to artswrapper if it is not already there - it should by default, but some distributors/packagers don't get this right. If you start artsd via kcminit, check the realtime checkbox, if you do manually, run artswrapper instead of artsd, i.e. stefan@voyager:~/src/kdelibs/arts$ artswrapper -F10 -S4096 >> running as realtime process now (priority 50) Artsd itself will not acquire RT prio, only artswrapper will. Noatun doesn't contain time critical code, so there it doesn't matter. Cu... Stefan -- -* Stefan Westerfeld, stefan@space.twc.de (PGP!), Hamburg/Germany KDE Developer, project infos at http://space.twc.de/~stefan/kde *-