> >Am Dienstag, den 31.07.2007, 10:26 +0200 schrieb Klaus Schulz: > >>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.
(re-sending my earlier reply to Klaus here on lkml too) Klaus, since you are using -rt, have you tried chrt-ing not only your audio player but your audio IRQ as well? While playback is going on could you create a system snapshot with the following tool: http://people.redhat.com/mingo/cfs-scheduler/tools/cfs-debug-info.sh and send me the output file. i'm also wondering why HZ=10000 makes a difference - audio interrupts have no Linux-timer aspect normally (they are hardware timers in essence themselves) - which portion of the workload is timing out so that HZ shows up? Does the enabling of CONFIG_HIGH_RES_TIMERS help perhaps? Also, do you have any advice for me how to reproduce your problem? I've got a couple of PCs with various low-end/chipset-based audio hw, but the buffers are generally large (around 500 msecs) so i rarely run into any xrun problems. Is your player available for download so i could try it? Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
