[linux-audio-user] Re: [Jackit-devel] [Fwd: Re: Linux audio latency]

[Florian Schmidt]

On Sat, 02 Oct 2004 16:58:57 -0400
Lee Revell <rlrevell at joe-job.com> wrote:

> Hey,
> 
> I have been helping this user get set up with 2.6+VP, and it really
> looks like the kernel is not the problem - the maximum latency
> reported by Ingo's tracer is under 200 usecs, but there are still
> xruns.  All my tests show that it should work at 128 or even 64 frames
> with this setup.  It really looks like jackd or the jack clients are
> the problem.
> 

One could rule this out by writing a minimal alsa app which does nothing
but writing/reading from an alsa device. Make it sched_fifo, mlock its
memory, and register the alsa xrun callback [if such a thing exists, i
know very little alsa_pcm programming]. Then see if it experiences
xruns, too. If not, then jackd is probably to blame.

Also maybe the alsa drivers themselfes might be problematic/buggy. If
the above minimal alsa app still produces xruns, then either alsa lib or
the drivers themselfes are to blame [probably].

Of course such a test is not a proof but might give important clues.

flo