[Musix-users] Re: Do I run a low-latency and realtime kernel?

Mon Apr 9 23:07:44 CEST 2007

Hi again,
Thanks for the replies !

> I suggest to Try the 2.6.16-multimedia kernel that it's into Musix,
> Also, the 2.6-16-beyond4.1 it's a realtime kernel...

Ok, I'll try the multimedia one.

> To try it, start jack and type into a konsole:
> ps -C jackd -cmL

my output is :
 PID   LWP CLS PRI TTY          TIME CMD
14745     - -     - ?        00:00:00 jackd
    - 14745 TS    7 -        00:00:00 -
    - 14746 TS   34 -        00:00:00 -
    - 14747 TS   22 -        00:00:00 -
    - 14748 #4   40 -        00:00:00 -
    - 14749 #4   40 -        00:00:00 -

So, no FF.. Does this mean no realtime kernel or no jackd realtime support?

> Julien: is realtime-lsm loaded?
> Type into a konsole:
> lsmod | grep realtime

The output from this comand is :
realtime                5384  0
commoncap         6912  1 realtime

Is this realtime-lsm?
(When I do apt-get install realtime-lsm it says it is already
installed. But do I have to turn it on? Or it is the above and is ok?)

> If you want more evidences:
> marcos at musix099b16:~$ cat /boot/config-2.6.17-2-multimedia-486 | grep -i realtime
> CONFIG_SECURITY_REALTIME=m

Mine is :
cat /boot/config-2.6.16-beyond4.1 |grep -i realtime
CONFIG_SECURITY_REALTIME=m

So it seems ok.

> Julien, what could be wrong with zynaddsubfx? or does it happends with any other apps?
Well, the tons of xruns and sound saturation comes only with
zynaddsubfx with that SPECIFIC configuration. That is :
midi keyboard -->midi input to freewheeling -->midi output to
zynaddsubfx -->audio output back to freewheeling -->audio output to
alsa_pcm.

I don't know what is bad with that configuration. May be it is the
fact that it makes a kind of loop, and so has to take too much time..

But in general, all soundfonts I use sound crap too. No saturation,
but bad sound quality (for that, I don't know, may be I only have bad
soundfonts)

So..let's summarize. With the commands you made me run, It seems I
have realtime kernel and realtime-lsm..but on the other hand, it seems
jackd is not realtime..??

Is your advice still to try the 2.16-multimedia?

Thanks !