Re: [PATCH] sched - Implement priority and fifo support for SCHED_ISO

[Con Kolivas <kernel@kolivas.org>]

Jack O'Quin wrote:
> Con Kolivas <kernel@kolivas.org> writes:
> 
> 
>>Sure enough I found the bug in less than 5 mins, and it would
>>definitely cause this terrible behaviour.
>>
>>A silly bracket transposition error on my part :P
> 
> 
> The corrected version works noticeably better, but still nowhere near
> as well as SCHED_FIFO.  The first run had a cluster of really bad
> xruns.  The second and third were much better, but still with numerous
> small xruns.
> 
>   http://www.joq.us/jack/benchmarks/sched-iso-fix/
> 
> With a compile running in the background it was a complete failure.
> Some kind of big xrun storm triggered a collapse on every attempt.
> 
>   http://www.joq.us/jack/benchmarks/sched-iso-fix+compile/
> 
> The summary statistics are mixed.  The delay_max is noticeably better
> than before, but still much worse than SCHED_FIFO.  But, the xruns are
> really bad news...

Excellent.

Believe it or not these look like good results to me. Your XRUNS are 
happening when the DSP load is >70% which is the iso_cpu % cutoff. Try 
setting the iso_cpu to 90%

echo 90 > /proc/sys/kernel/iso_cpu

Cheers,
Con