[linux-audio-user] jackd --realtime eats my memory.

Lee Revell rlrevell at joe-job.com
Sat Feb 26 16:18:20 EST 2005

On Sat, 2005-02-26 at 13:04 -0800, Jan Holst Jensen wrote:
> Is "--realtime" forcing jackd and its clients to lock
> all of their memory in RAM ?


>  I would then need quite a
> lot of RAM to use the "--realtime" option. Is it
> really necessary to use _that_ much RAM ?

No.  Try running jackd with the --unlock option.  From the man page:

       -u, --unlock
              Unlock libraries GTK+, QT, FLTK, Wine.

This is the best solution.  JACK clients should never use GTK+, QT, or
FLTK in the audio thread anyway, so this will not bother correctly
written JACK clients.

If this does not help, try this:

       -m, --no-mlock
              Do not attempt to lock memory, even if --realtime.

This will obviously increase the change of xruns, because now a page
fault in the process() callback is possible.

For more information see "man jackd".

> I also tried to renice jackd with -20 so it runs with
> priority 0. Will the "--realtime" option give me
> better stability than the renicing ?

Yes, absolutely.  Renicing JACK is the wrong way, because it's still
subject to dynamic priority adjustment by the scheduler.


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