[linux-audio-user] Tracking down overruns

[Benji Flaming]

> Even if something else is causing my overruns now, I certainly suspect
that
> real-time performance could be enhanced by a bit of cache settings
tweaking.
> If anyone has any info on doing this with a 2.6.test5 kernel, I would love
> to get it.  My curiosity has been awakened :)

I ought to be in bed right now, but I did manage to find what I was looking
for.  The values I want to adjust are in /proc/sys/vm/.  Some basic
observations about the effects of different cache settings on I/O
performance can be found at:

http://drscriptt.riverviewtech.net/linux/enotes/bdflush.html

I also found a page with some other potentially useful information for
tracking down hard disk I/O operations (although the goal of the document is
quite unrelated to audio streaming):

http://www-2.cs.cmu.edu/~mukesh/hacks/spindown/t1.html

Lastly, I changed the IO_support setting to 1, and Ardour has now been
happily recording for an hour and a half!  I was also able to run the
latency test without overruns (the 4 ms. spike dropped to 2.7 ms.).  Thanks
so much for your help, Mark & Jan!

I'll be looking into the disk caching parameters, and if I come up with any
promising results, I'll certainly post my findings.

Best regards,

|)
|)enji

Benjamin Flaming
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"The trouble with computers, of course, is that they're very sophisticated
idiots."