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

[Con Kolivas <kernel@kolivas.org>]

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Jack O'Quin wrote:
> Con Kolivas <kernel@kolivas.org> 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.  

I installed a fresh jack installation and got the test suite. I tried 
running the test suite and found it only ran to completion if I changed 
the run time right down to 30 seconds from 300. Otherwise it bombed out 
almost instantly at the default of 300. I don't know if that helps you 
debug the problem or not but it might be worth mentioning.

As for my own results I gave it a run on the weak SCHED_ISO 
implementation in 2.6.10-ck5 (P4HT 3.06):

SCHED_NORMAL:
*********************************************
Timeout Count . . . . . . . . :(    0)
XRUN Count  . . . . . . . . . :    74
Delay Count (>spare time) . . :     0
Delay Count (>1000 usecs) . . :     0
Delay Maximum . . . . . . . . :     0   usecs
Cycle Maximum . . . . . . . . :  1046   usecs
Average DSP Load. . . . . . . :    18.0 %
Average CPU System Load . . . :     2.5 %
Average CPU User Load . . . . :     7.8 %
Average CPU Nice Load . . . . :     0.1 %
Average CPU I/O Wait Load . . :     0.1 %
Average CPU IRQ Load  . . . . :     0.1 %
Average CPU Soft-IRQ Load . . :     0.0 %
Average Interrupt Rate  . . . :  1776.0 /sec
Average Context-Switch Rate . : 10290.4 /sec
*********************************************

SCHED_NORMAL nice -n -20:
*********************************************
Timeout Count . . . . . . . . :(    0)
XRUN Count  . . . . . . . . . :   266
Delay Count (>spare time) . . :     0
Delay Count (>1000 usecs) . . :     0
Delay Maximum . . . . . . . . :     0   usecs
Cycle Maximum . . . . . . . . :  2239   usecs
Average DSP Load. . . . . . . :    28.6 %
Average CPU System Load . . . :     2.9 %
Average CPU User Load . . . . :    10.2 %
Average CPU Nice Load . . . . :     0.0 %
Average CPU I/O Wait Load . . :     1.0 %
Average CPU IRQ Load  . . . . :     0.2 %
Average CPU Soft-IRQ Load . . :     0.1 %
Average Interrupt Rate  . . . :  2049.7 /sec
Average Context-Switch Rate . : 10145.1 /sec
*********************************************

SCHED_ISO:
*********************************************
Timeout Count . . . . . . . . :(    0)
XRUN Count  . . . . . . . . . :     1
Delay Count (>spare time) . . :     0
Delay Count (>1000 usecs) . . :     0
Delay Maximum . . . . . . . . :     0   usecs
Cycle Maximum . . . . . . . . :   687   usecs
Average DSP Load. . . . . . . :    19.9 %
Average CPU System Load . . . :     2.6 %
Average CPU User Load . . . . :    10.3 %
Average CPU Nice Load . . . . :     0.0 %
Average CPU I/O Wait Load . . :     0.0 %
Average CPU IRQ Load  . . . . :     0.2 %
Average CPU Soft-IRQ Load . . :     0.3 %
Average Interrupt Rate  . . . :  2166.2 /sec
Average Context-Switch Rate . : 10117.3 /sec
*********************************************

SCHED_FIFO:
*********************************************
Timeout Count . . . . . . . . :(    0)
XRUN Count  . . . . . . . . . :     2
Delay Count (>spare time) . . :     0
Delay Count (>1000 usecs) . . :     0
Delay Maximum . . . . . . . . :     0   usecs
Cycle Maximum . . . . . . . . :   544   usecs
Average DSP Load. . . . . . . :    19.5 %
Average CPU System Load . . . :     3.1 %
Average CPU User Load . . . . :    12.6 %
Average CPU Nice Load . . . . :     0.0 %
Average CPU I/O Wait Load . . :     0.0 %
Average CPU IRQ Load  . . . . :     1.0 %
Average CPU Soft-IRQ Load . . :     1.1 %
Average Interrupt Rate  . . . :  5018.4 /sec
Average Context-Switch Rate . : 10902.5 /sec
*********************************************


It occasionally would segfault on client exit as well (as you've already 
mentioned). I think we're still in the dark here to be honest.

Con

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