[linux-audio-dev] Re: [vst-plugins] Plugin server

[Kai Vehmanen]

On Sun, 8 Dec 2002, Paul Davis wrote:

> you also haven't addressed kernel scheduling issues; the context
> switch doesn't happen till the kernel has decided what task is going
> to run next. if it picks the wrong one, for whatever reason, then
> you/we lose. right now, it picks the wrong one too often, even with
> SCHED_FIFO+mlockall.

Btw; have you tried the O(1) scheduler? It has a number of interesting
charasteristics from an audio app developer's pov [1]:

- RT-scheduling is, too, O(1) (less cache use, quicker context 
  switches...)
- RT-scheduling is separated from non-RT scheduling 
- perfect SMP-scalability (no shared run-queue lock)

And of course, as O(1) is under active development (in 2.5, in 2.4-ac
and patches for latest 2.4 kernels), a possible bug in SCHED_FIFO 
semantics might receive kernel-hacker interest. ;)

Do you have any simple test cases to reproduce the problem... only
with ardour+jackd or perhaps also simpler setups like jackd+capture_client 
or some such?

[1] http://www.uwsg.iu.edu/hypermail/linux/kernel/0201.0/0810.html

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