From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 22 Sep 2001 17:19:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 22 Sep 2001 17:19:27 -0400 Received: from paloma17.e0k.nbg-hannover.de ([62.159.219.17]:22984 "HELO paloma17.e0k.nbg-hannover.de") by vger.kernel.org with SMTP id ; Sat, 22 Sep 2001 17:19:15 -0400 Content-Type: text/plain; charset="iso-8859-1" From: Dieter =?iso-8859-1?q?N=FCtzel?= Organization: DN To: george anzinger , Robert Love Subject: Re: [PATCH] Preemption Latency Measurement Tool Date: Sat, 22 Sep 2001 23:09:22 +0200 X-Mailer: KMail [version 1.3.1] Cc: Oliver Xymoron , Andrea Arcangeli , Roger Larsson , linux-kernel , ReiserFS List In-Reply-To: <1001042255.7291.39.camel@phantasy> <3BAB614E.8600D074@mvista.com> In-Reply-To: <3BAB614E.8600D074@mvista.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <20010922211919Z272247-760+15646@vger.kernel.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Freitag, 21. September 2001 17:48 schrieb george anzinger: > Robert Love wrote: > > On Thu, 2001-09-20 at 18:51, Dieter Nützel wrote: > > > > Does your audio source depend on any files (eg mp3s) and if so, could > > > > they be moved to a ramfs? Do the skips go away then? > > > > > > Good point. > > > > > > I've copied one video (MP2) and one Ogg-Vorbis file into /dev/shm. > > > Little bit better but hiccup still there :-( > > > > As I've been saying, the problem really shouldn't be disk I/O. I would > > think (and really hope) the readahead code can fit a little mp3 in > > memory. Even if not, its a quick read to load it. The continued blips > > you see are caused by something, well, continual :) > > Are you running your application at some real time priority? I suspect > that, when dbench starts, it floods the system with a lot of new tasks > and the system must visit each one until it gets back to your ap. Nice > will only do so much here. Real time priority is the way to go. > Attached are a couple of small programs to help here. "rt" runs a given > ap at a given priority. I.e. > rt 10 foo, runs foo at priority 10. > (There are more options, try rt -h.) getrt reports the priority of a > task. If you do something like > rt 10 bash everything you run from > the new bash prompt will be at priority 10. You must be root to run rt Yes, I do like I've posted in all the related threads. Here is some more input for you. I hope it could help nail it down. Regards, Dieter BTW I'll now switching to 2.4.10-pre14 SunWave1#time tar xIf /Pakete/Linux/linux-2.4.9.tar.bz2 34.570u 5.350s 0:47.84 83.4% 0+0k 0+0io 295pf+0w I "hear" some have disk activities (disk trashing). SunWave1#sync Runs for ages!!! User CPU 0% System CPU 0% Idle CPU 99% So where did it wait??? Here comes what latencytimes show: Worst 20 latency times of 5061 measured in this period. usec cause mask start line/file address end line/file 322263 reacqBKL 1 1375/sched.c c01138b4 697/sched.c 216174 BKL 1 30/inode.c c016b971 52/inode.c 158328 BKL 9 742/block_dev.c c0144d51 697/sched.c 66975 BKL 1 1101/super.c c014250d 697/sched.c 53560 BKL 1 1101/super.c c014250d 1130/super.c 37742 spin_lock 1 547/sched.c c0111b04 795/block_dev.c 24822 spin_lock 1 678/inode.c c01551f7 704/inode.c 24739 spin_lock 1 291/buffer.c c014003c 285/buffer.c 19330 spin_lock 1 547/sched.c c0111b04 697/sched.c 16566 BKL 1 30/inode.c c016b971 697/sched.c 14049 spin_lock 1 2043/tcp_ipv6.c e9078837 119/softirq.c 11993 spin_lock 1 2111/tcp_ipv4.c c0220517 119/softirq.c 11704 BKL 1 706/block_dev.c c0144bd7 1381/sched.c 11405 spin_lock 1 291/buffer.c c014003c 280/buffer.c 11288 BKL 1 706/block_dev.c c0144bd7 697/sched.c 11213 reacqBKL 9 1375/sched.c c01138b4 696/block_dev.c 11212 spin_lock 1 547/sched.c c0111b04 696/block_dev.c 7552 spin_lock 1 298/buffer.c c013bb1c 285/buffer.c 5013 BKL 0 2763/buffer.c c013fbca 697/sched.c 4641 BKL 1 1302/inode.c c016de79 697/sched.c SunWave1#ksymoops -m /boot/System.map -A " c01138b4 c016b971 c0144d51 c014250d c014250d c0111b04 c01551f7 c014003c c0111b04 c016b971 e9078837 c0220517 c0144bd7 c014003c c0144bd7 c01138b4 c0111b04 c013bb1c c013fbca c016de79" ksymoops 2.4.3 on i686 2.4.10-pre12-preempt. Options used -V (default) -k /proc/ksyms (default) -l /proc/modules (default) -o /lib/modules/2.4.10-pre12-preempt/ (default) -m /boot/System.map (specified) Adhoc c01138b4 Adhoc c016b970 Adhoc c0144d50 Adhoc c014250c Adhoc c014250c Adhoc c0111b04 Adhoc c01551f6 Adhoc c014003c Adhoc c0111b04 Adhoc c016b970 Adhoc e9078836 <[ipv6]tcp6_get_info+4a6/770> Adhoc c0220516 Adhoc c0144bd6 Adhoc c014003c Adhoc c0144bd6 Adhoc c01138b4 Adhoc c0111b04 Adhoc c013bb1c Adhoc c013fbca Adhoc c016de78