Re: [PATCH]sched: Isochronous class v2 for unprivileged soft rt scheduling

[Con Kolivas <kernel@kolivas.org>]

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Con Kolivas wrote:
> There were numerous bugs in the SCHED_ISO design prior to now, so it 
> really was not performing as expected. What is most interesting is that 
> the DSP load goes to much higher levels now if xruns are avoided and 
> stay at those high levels. If I push the cpu load too much so that they 
> get transiently throttled from SCHED_ISO, after the Xrun the dsp load 
> drops to half. Is this expected behaviour?
> 
> Anyway the next patch works well in my environment. Jack, while I 
> realise you're getting the results you want from Ingo's dropped 
> privilege, dropped cpu limit patch I would appreciate you testing this 
> patch. It is not clear yet what direction we will take, but even if we 
> dont do this, it would be nice just because of the effort on my part.
> 
> This version of the patch has full priority support and both ISO_RR and 
> ISO_FIFO.
> 
> This is the patch to apply to 2.6.11-rc2-mm1:
> http://ck.kolivas.org/patches/SCHED_ISO/2.6.11-rc2-mm1/2.6.11-rc2-mm1-iso-prio-fifo.diff 

Just for completeness, benchmarks:
logs and pretty pictures:
http://ck.kolivas.org/patches/SCHED_ISO/iso3-benchmarks/

SCHED_ISO:
Total seconds ran . . . . . . :   300
Number of clients . . . . . . :    10
Ports per client  . . . . . . :     4
Frames per buffer . . . . . . :    64
Number of runs  . . . . . . . :(    3)
Timeout Count . . . . . . . . :(    0)
XRUN Count  . . . . . . . . . :     0
Delay Count (>spare time) . . :     0
Delay Count (>1000 usecs) . . :     0
Delay Maximum . . . . . . . . :   150   usecs
Cycle Maximum . . . . . . . . :   725   usecs
Average DSP Load. . . . . . . :    32.3 %
Average CPU System Load . . . :     6.0 %
Average CPU User Load . . . . :    33.6 %
Average CPU Nice Load . . . . :     0.0 %
Average CPU I/O Wait Load . . :     0.1 %
Average CPU IRQ Load  . . . . :     0.1 %
Average CPU Soft-IRQ Load . . :     0.0 %
Average Interrupt Rate  . . . :  1758.9 /sec
Average Context-Switch Rate . :  9208.7 /sec


and SCHED_ISO in the presence of continuous compile:

Total seconds ran . . . . . . :   300
Number of clients . . . . . . :    10
Ports per client  . . . . . . :     4
Frames per buffer . . . . . . :    64
Number of runs  . . . . . . . :(    3)
Timeout Count . . . . . . . . :(    0)
XRUN Count  . . . . . . . . . :     0
Delay Count (>spare time) . . :     0
Delay Count (>1000 usecs) . . :     0
Delay Maximum . . . . . . . . :   375   usecs
Cycle Maximum . . . . . . . . :   726   usecs
Average DSP Load. . . . . . . :    35.8 %
Average CPU System Load . . . :    15.1 %
Average CPU User Load . . . . :    82.9 %
Average CPU Nice Load . . . . :     0.0 %
Average CPU I/O Wait Load . . :     1.8 %
Average CPU IRQ Load  . . . . :     0.2 %
Average CPU Soft-IRQ Load . . :     0.0 %
Average Interrupt Rate  . . . :  1772.6 /sec
Average Context-Switch Rate . :  9565.2 /sec


Cheers,
Con

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