linuxaudio.org

"Shayne O'Connor"  writes:
> one thing i noticed is that whenever an audio app is started from the

quoted text
> terminal, it prints this out:

>

> cannot lock down memory for RT thread (Cannot allocate memory)

>

> though, in regards to what i mention above, this message doesn't seem to

> have had an effect on performance ... what does it mean? surely jack at

> least has RT access?!

The realtime-lsm grants memory locking privileges as well as

scheduling privileges.  This is not essential, may systems will work

fine without it.  But, if you are tight on memory, you may see rather

drastic xruns due to something getting paged out.  Normally, the

realtime pages are "hot" enough to stay resident, anyway.  That is why

JACK does not consider this a fatal error, even when running with -R.
If you are doing something critical (like recording a band), you

should probably also grant mlock() privileges.  This is already

supported via rlimits in 2.6 kernels.  Check it using the `ulimit -l'

command.  The default limit is probably rather small.
Perhaps someone can explain how to do this using PAM.  I believe you

set the `memlock' option in `/etc/security/limits.conf', somehow.

--

  joq