From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761298AbXGaNBi (ORCPT ); Tue, 31 Jul 2007 09:01:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759244AbXGaNB1 (ORCPT ); Tue, 31 Jul 2007 09:01:27 -0400 Received: from tristate.vision.ee ([194.204.30.144]:41719 "HELO mail.city.ee" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757987AbXGaNBZ (ORCPT ); Tue, 31 Jul 2007 09:01:25 -0400 X-Greylist: delayed 400 seconds by postgrey-1.27 at vger.kernel.org; Tue, 31 Jul 2007 09:01:25 EDT Message-ID: <46AF3111.7090206@city.ee> Date: Tue, 31 Jul 2007 15:54:41 +0300 From: =?UTF-8?B?TGVuYXIgTMO1aG11cw==?= User-Agent: Thunderbird 2.0.0.5 (X11/20070723) MIME-Version: 1.0 To: Klaus Schulz CC: ck@vds.kolivas.org, linux-kernel@vger.kernel.org, mingo@elte.hu Subject: Re: ck vs. cfs : realtime audio performance References: <1185870355.7933.55.camel@klaus-laptop> <1185886161.7397.11.camel@klaus-laptop> In-Reply-To: <1185886161.7397.11.camel@klaus-laptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Cc'd to LKML & Ingo. L. Klaus Schulz wrote: > Hi there. > > > > > Am Dienstag, den 31.07.2007, 10:26 +0200 schrieb Klaus Schulz: > >> Hi folks. >> >> I am currently testing the 2.6.22.1 cfs-rt9 vs. ck1 on my rather pure >> realtime high-end-audio setup. (NO X, just a terminal, streaming .wav. >> I am using my own written player and brutefir as the audio engine.) >> Comment: This is not a standard (amarok or xmms setup), all buffers in >> the chain are very small. Any problem will immidetialy end up in xruns. >> The sounddriver, HW (pci-bus etc.) are tweaked accordingly >> >> Until now ck1 on 2.6.22 is giving me better results (less audible >> distortions) and runs extremely stable compared to cfs. >> Under ck I ran my player with schedtool -R -p 98, which was better than >> running it e.g. with nice -20 >> Both setups under cfs were giving me worse results than ck. >> With CFS I also experienced XRUNS from time to time, what never happened >> with ck. >> >> However: >> >> When looking at the latest performance statistics cfs vs. ck which are >> spread around here, I am wondering, what might cause the differences. >> >> With ck I tweaked the rr_interval to 6 and was running at 10000Hz, >> which caused obvious improvements. >> >> These options I do not have with CFS. >> >> I am wondering if sched_granularity_ns should be touched when using cfs. >> I googled somewhere that bringing it down to e.g. 250000 instead of >> 4000000 would smoothen the audio playback. I havn't tried it yet. I am >> wondering if this tweak is still applicable. >> > > > > I did test now decreasing the sched_granularity_ns to 250000. > There is still a clearly audible difference comparing ck and cfs. > ck Ídelivers cristal clear sound. With cfs I still get quite some > distortions. > > Any hints how to improve the situtation are welcome. > > > > >> I'd be happy to get a hint on how to tweak the system parameters best to >> give cfs a fair chance. I am also wondering how the timer freqency could >> by increased under a cfs-patched kernel. >> >> Info: dynamic ticks and IRQ balancing are off for the time being. >> /proc/sys/dev/rtc is set to 4096 (gave me best results) >> ( I don't have a clue how all the (rtc)-timers in the OS interact, >> To me it is just a trial and error exercise to figure out which >> setup sounds best) >> >> THX for your advise. >> >> Cheers >> \Klaus >> > > > Cheers > \Klaus > > > _______________________________________________ > http://ck.kolivas.org/faqs/replying-to-mailing-list.txt > ck mailing list - mailto: ck@vds.kolivas.org > http://vds.kolivas.org/mailman/listinfo/ck >