[LAU] realtime priority - FIFO vs Round Robin and scheduling

From: Luka Prinčič / Nova deViator <nova@email-addr-hidden>
Date: Tue May 24 2016 - 15:31:37 EEST

hi Linux audio community!

i've been strugling with XRUNS and glitches on a machine using Renoise,
SuperCollider and Processing. i wrote a question also on Renoise forum,
but everything boils down to this:

Renoise seems to be running some threads with FIFO scheduler with a
priority that is _below_ that of JACK and firewire driver (correct
right?), but ALSO some threads using Round Robin scheduler with VERY
HIGH RT priority of 95. my question is if this is a possible cause for
glitches and XRUNS? the priority of 95 is above realtime clock (RTC)
and firewire irq! i wonder if Round Robin scheduler isn't somewhat less
stressful for the system and FIFO threads would still have priority?

PRI RTPRIO CLS PID NI CMD
135 95 RR 2255 - renoise
135 95 RR 2255 - renoise
130 90 FF 114 - [irq/8-rtc0]
125 85 FF 200 - [irq/20-firewire]
106 66 FF 2583 - jackd -R -P 60 -d firewire -r 44100 -p 128 -n 3

so i'm asking Renoise guys if they know anything about it.

to test, is there a way to start a process and force to use different
scheduler AND/OR change priority?

chrt reports Renoise is using SCHED_OTHER.

any ideas greatly appreciated.

the full forum post (with more data) is here:
http://forum.renoise.com/index.php/topic/47767-linux-priority-too-high/

best,
Luka

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Received on Tue May 24 16:15:01 2016

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