[LAU] xrun problems. (Was Re: Introduction to Ardour 3.0 MIDI)

[jy]

My experience is the following :

I had a serious xruns problem using both the internal sound card of my
laptop and my M-Audio MobilePre USB sound card.
After trying a lot of things, the only config that worked for me was to set
my rtprio at priority of the real-time clock minus 11 (so that the jack
watchdog is just under the real-time clock).
These are rather low values : priority is 50 for the rtc and 39 for rtprio
in my limits.conf

but since i set up this configuration, everything runs smoothly at just
under 10 ms using 3 instances of yoshimi, hydrogen, seq24 ardour and
eventually a gx_head with my guitar as input. No xruns at all !!

I used "ps -eo rtprio,cmd" to check the rtc value with my realtime kernel.

hope it can be of any help...

jy

2011/3/30 Uwaysi Bin Kareem <uwaysi.bin.kareem at paradoxuncreated.com>

> I found that I could run 0.363 ms latency, quite easily. No dropouts, if
> just running renoise.
> I did compile a kernel where I turned off all that I could though. What I
> remember offhand - maximum level of preemption (no need for rt kernel).
> Preemptible RCU,
> SLAB (doesn't do as much stuff as slub, and probably therefore has lower
> latencies)
> I didn't find enabling tickless to be a problem.
> 250hz timer.
> Turning off IOMMU's, and similar things. You don't need them on boxes that
> has below 4GB RAM. IOMMU adds to latency.
> Disabling all debugging, hacking, securtity, and other stuff you don't
> need.
>
> Also you need to make sure that realtime-threads get the highest priority.
> I also had to modify rtprio to 99 and nice to -20, in
> /etc/security/limits.d/audio.conf on ubuntu natty.
>
> This is my full local config.
>
> http://pastebin.com/JCie5RRN
>
> I'm on a core2duo, also using a nvidia gtx280, without problems. 0.363 ms
> latency was with renoise, jackd and konnekt24d.
> The kernel is 2.6.36-zen0
> http://downloads.zen-kernel.org/snapshots/zen-stable/linux-2.6-zen.v2.6.36-zen0-full-git.tar.gz
>
> I use this because it has some low latency patches, from 38 and 37 on top
> of 36, which has the old firewire stack.
>
> Peace,
> Uwaysi.
> _______________________________________________
> Linux-audio-user mailing list
> Linux-audio-user at lists.linuxaudio.org
> http://lists.linuxaudio.org/listinfo/linux-audio-user
>
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