[LAU] Jack frequently crashes when running LinuxSampler + Qsynth

Guru Prasad B. R. prasadbrg at gmail.com
Mon Oct 19 07:10:15 EDT 2009


Jörn Nettingsmeier wrote:
> that doesn't mean the system is within its limits. if you have, say, a
> background task running that will cause very short load spikes to 100%
> (which you won't necessarily see in any monitoring tool, as most do some
> averaging over time), and you don't have taken precautions to give your
> audio priority over those (by running jack in realtime mode and possibly
> by running an rt kernel), your audio will glitch, or worse, the audio
> will get stuck in the way you described.
>
> but for now, you will have to ensure that nothing
> ever stalls your audio processes.
>
> so:
> * run jackd as realtime
> * maybe increase the period size a bit (what are you using atm?)
> * kill background tasks (networkmanager, cron, ...)
> * try an rt kernel (31.4-rt14 gives me very good results)
>   
Thanks Jörn, for the reply!
  Sorry, I forgot to mention the following:
- I'm running the Ubuntu realtime kernel: 2.6.28-3-rt
- The 'realtime' option in qjackctl is checked
- I've also tried using icewm, and using 'free -m', I find that upto 
500MB  of memory is freed.

So I have the following questions:
- How do I check whether the realtime stuff is doing it's job properly?
- Which are the processes that I should manually kill?
- Apart from staring at the system monitor as I bang the keyboard, is 
there a more scientific manner of logging a time-series of system 
resource usage (of course, the time resolution would necessarily need to 
be quite high), which will conclusively show that cpu usage actually 
spiked just before the instant that jack crashed?

Jörn Nettingsmeier wrote:

maybe there is a way to make jack and applications more robust (just have a dropout, then continue as normal)


Now this sounds ideal! What do I do to make this happen? Is there some 
way I can provide constructive feedback to the good folks behind jack 
and applications? It would be next to tragic if, despite all those 
wonderful applications, totalling thousands of man-hours of effort, nice 
GUIs, so many thoughtful features, none of them are stage-worthy, from a 
professional musician's perspective...
I eagerly look forward to your suggestions... I need help with this, and 
would sincerely appreciate any pointers.
Cheers!

Guru





More information about the Linux-audio-user mailing list