Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.30-2

[Ingo Molnar]

> since the client runs as SCHED_OTHER, doesnt this mean that simple
> delays between SCHED_OTHER tasks could cause xruns in jackd too? A
> SCHED_OTHER task can be delayed indefinitely at any stage. So shouldnt
> the test-clients have RT priority as well, to guarantee xrun-less
> jackd?

if SCHED_OTHER is the goal, then the xruns you are seeing in the
fluidsynth test are likely the result of random fluctuations in
scheduling of SCHED_OTHER tasks.

The way to find out whether that's the main source of xruns would be the
following test: start each fluidsynth instance as "nice -19 fluidsynth
..." to renice it to +19. Nice +19 gives the smoothest timeslices to
CPU-bound tasks (such as fluidsynth), and should give the smallest
global fluctuations. (The system must be idle during the test of course,
a nice +19 task is easily preempted.)

	Ingo
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