Re: [PATCH][RFC] sched: Isochronous class for unprivileged soft rtscheduling

From: Jack O'Quin
Date: Wed Jan 19 2005 - 01:54:05 EST

Con Kolivas <kernel@xxxxxxxxxxx> writes:

> This patch for 2.6.11-rc1 provides a method of providing real time
> scheduling to unprivileged users which increasingly is desired for
> multimedia workloads.

I ran some jack_test3.2 runs with this, using all the default
settings. The results of three runs differ quite significantly for no
obvious reason. I can't figure out why the DSP load should vary so
much.

These may be bogus results. It looks like a libjack bug sometimes
causes clients to crash when deactivating. I will investigate more
tomorrow, and come up with a fix.

For comparison, I also made a couple of runs using the realtime-lsm to
grant SCHED_FIFO privileges. There was some variablility, but nowhere
near as much (and no crashes). I used schedtool to verify that the
jackd threads actually have the expected scheduler type.

============================================
Unprivileged, realtime threads are SCHED_ISO
============================================

*** Terminated Tue Jan 18 23:54:55 CST 2005 ***
************* SUMMARY RESULT ****************
Total seconds ran . . . . . . : 300
Number of clients . . . . . . : 20
Ports per client . . . . . . : 4
Frames per buffer . . . . . . : 64
*********************************************
Timeout Count . . . . . . . . :( 3) ( 14) ( 2)
XRUN Count . . . . . . . . . : 10 42 3
Delay Count (>spare time) . . : 1 0 0
Delay Count (>1000 usecs) . . : 0 0 0
Delay Maximum . . . . . . . . : 307419 usecs 6492 usecs 19339 usecs
Cycle Maximum . . . . . . . . : 858 usecs 866 usecs 860 usecs
Average DSP Load. . . . . . . : 37.3 % 14.5 % 37.7 %
Average CPU System Load . . . : 10.2 % 4.5 % 10.0 %
Average CPU User Load . . . . : 26.6 % 11.4 % 23.8 %
Average CPU Nice Load . . . . : 0.0 % 0.0 % 0.0 %
Average CPU I/O Wait Load . . : 2.0 % 0.7 % 0.2 %
Average CPU IRQ Load . . . . : 0.8 % 0.7 % 0.7 %
Average CPU Soft-IRQ Load . . : 0.0 % 0.0 % 0.0 %
Average Interrupt Rate . . . : 1730.3 /sec 1695.5 /sec 1694.8 /sec
Average Context-Switch Rate . : 11523.1 /sec 6151.1 /sec 11672.2 /sec
*********************************************


==================================================
With CAP_SYS_NICE, realtime threads are SCHED_FIFO
==================================================

*** Terminated Tue Jan 18 23:41:42 CST 2005 ***
************* SUMMARY RESULT ****************
Total seconds ran . . . . . . : 300
Number of clients . . . . . . : 20
Ports per client . . . . . . : 4
Frames per buffer . . . . . . : 64
*********************************************
Timeout Count . . . . . . . . :( 0) ( 0)
XRUN Count . . . . . . . . . : 0 0
Delay Count (>spare time) . . : 0 0
Delay Count (>1000 usecs) . . : 0 0
Delay Maximum . . . . . . . . : 331 usecs 201 usecs
Cycle Maximum . . . . . . . . : 882 usecs 1017 usecs
Average DSP Load. . . . . . . : 40.7 % 41.7 %
Average CPU System Load . . . : 11.1 % 10.9 %
Average CPU User Load . . . . : 26.7 % 27.7 %
Average CPU Nice Load . . . . : 0.0 % 0.0 %
Average CPU I/O Wait Load . . : 0.6 % 1.0 %
Average CPU IRQ Load . . . . : 0.7 % 0.7 %
Average CPU Soft-IRQ Load . . : 0.0 % 0.0 %
Average Interrupt Rate . . . : 1708.0 /sec 1697.1 /sec
Average Context-Switch Rate . : 13297.0 /sec 13314.8 /sec
*********************************************

--
joq
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