Hi Sam,
We do set thread priorities but if your user account doesn't have the
permissions to set them via /etc/security/limits.conf then these priority
changes do nothing. Have you made this change?
http://www.gentoo.org/proj/en/desktop/sound/realtime.xml
See the bit about 'rtprio'.
Thanks,
RJ
On Thu, Feb 14, 2013 at 10:10 AM, Sam Martin <sam.mar...@geomerics.com>wrote:
> Hi everyone,****
>
> ** **
>
> I’ve been looking at things that force my Ubuntu linux install of Mixx to
> miss buffer updates (audio glitches). I have a low latency kernel installed
> with the usual low latency linux tweaks, and a uca202 audio interface, but
> see glitches even when running with large buffer sizes. ****
>
> ** **
>
> I had some success by using htop (a basic linux performance monitor) to
> monitor cpu intensive applications, and boosting the ‘niceness’ of non-mixx
> applications. Making metacity, x11 and other graphics-related apps nicer
> helps, but it turns out the biggest glitches actually come from mixx itself.
> ****
>
> ** **
>
> I haven’t studied the code yet, but it appears to launch a fairly large
> number of threads which compete equally for cpu time. I’ve found that if I
> make the main mixx thread nicer (effectively decreasing it’s scheduling
> priority and making it more likely to be pre-emptied), and identify and do
> the same to the threads that seem to do analysis work when you first load a
> track, the vast majority of glitches go away. I’m guessing the kernel is
> then doing a better job at pre-empting these threads, allowing the time
> critical ones to run promptly.****
>
> ** **
>
> So, is mixx doing anything to hint about which of its threads are high/low
> priority? Could it be setting the niceness of each thread (at least on
> linux) based on context somehow?****
>
> ** **
>
> If this sounds sensible, and someone can give me a few pointers to get
> started, I’d be happy to consider making a patch.****
>
> ** **
>
> Cheers,****
>
> Sam****
>
> ** **
>
> p.s. great work btw!****
>
> ** **
>
> ** **
>
>
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