Messages in this thread | | | Date | Mon, 28 Jul 2003 21:27:50 +0100 (BST) | From | Steven Newbury <> | Subject | SCHED_SOFTRR patch |
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I personally see your SCHED_SOFTRR as the correct solution for multimedia applications. But as it is currently tuned I have been unable to get it to work adequately with a relatively undemanding program, XMMS. I say undemanding because XMMS only uses about 2-4% CPU time on my test machine (P3/933MHz) when playing mp3's.
While testing SCHED_SOFTRR with XMMS I had to modify XMMS slightly since it usually checks for uid 0 before enabling SCHED_RR.
Under 2.6.0-test1 based kernels I have experienced quite a lote of drop-outs with XMMS playing mp3's with a moderate load, however, when run as root (with SCHED_RR) I encountered no drop-outs at all. When using SOFTRR under I had very choppy playback when the machine was under load. It was a constant jittering more than intermittent drop-outs.
I have been using a 2.6.0-test2-O10int based kernel in my latest tests.
With 2.6.0-test2-O10int it is very hard to get drop-outs unless I run it with SCHED_SOFTRR! The jitteriness is gone but a moderate load causes dropouts, much like non SCHED_RR on 2.6.0-test1 based kernels. SCHED_RR still runs perfectly though. It could be that SCHED_SOFTRR is being too "tight" with the CPU time it is giving the Real-Time thread.
I have tried various values for the SCHED_TS_KSOFTRR, MIN_SRT_TIMESLICE, MAX_SRT_TIMESLICE constants, but have been as yet unable to find values that produce a good result.
The lattest.c program does show that SOFT_RR is working as does top which shows RT priority for XMMS.
===== Steve
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