[linux-audio-dev] Realtime audio and IO schedulers

[Florian Schmidt]

On Sun, 23 Jan 2005 09:40:32 +1100
Cal <hihone at bigpond.net.au> wrote:

> This may be late/redundant/boring, but such is life when you deal with
> digests.  Jens Axboe's cfq-ts patch fits pretty close to what you
> describe, and comes with a utility for setting the io priority.  It's
> been getting quite a healthy workout by ck mailing list members.  I gave
> it a good push with Ardour at one point, but then life got in the way. 
> Jens' last post/patch (that I saw) is at
> http://bhhdoa.org.au/pipermail/ck/2005-January/002650.html
> 
> It'd be worth skimming the ck archive <http://bhhdoa.org.au/pipermail/ck/>
> for hurrahs, horror stories and info on the ionice utility before diving
> in though - the earlier warnings on experimentalism are wise counsel. 

Thanks for the pointers. I will give it a try :)

Btw: i read this mail of yours in the archives:

------
"Hi Con,

This has to be within the realm of dumb questions, and much more likely 
to be related to jackd rather than the scheduler, but, if you don't 
mind, I'll float it to you and ck at large rather than directly to lkml 
(and the bunch of heavy duty groupies your patch has attracted).

When running jack_test4.1 with LD_ASSUME_KERNEL=2.4.19 set, schedtool 
shows all the appropriate threads as sched_iso.  Without 
LD_ASSUME_KERNEL set, there isn't a sched_iso thread to be seen. They 
all appear to be sched_normal.

No, no, no ... no suggestion of "It's all your fault!", just thought you 
might be able to offer the simple explanation (with minimum embarassment 
to moi).

cheers, Cal"
-------

This smells much like the classic nptl-hell some jackd users
experienced. See this page:

http://www.affenbande.org/~tapas/wiki/index.php?Jackd%20and%20NPTL

and tell me what 

getconf GNU_LIBPTHREAD_VERSION

reports on your system. The above page also points to a (a little more
detailed) debian bug report. This is imho a glibc issue and not a kernel
issue. But the issue only shows in combination with 2.6.x kernels, since
2.4.x kernels used the linuxthreads system, not nptl..

Flo


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