[linux-audio-user] Low latency kernel on Mandrake

[Austin]

On Sun, 2003-11-02 at 11:40, Joe Button wrote:
> I thought that _ought_ to be the case but I was suspicious because of the 
> /proc/sys/kernel/lowlatency thing

Yeah, I dunno why Danny made it that way.  I think just to make sure
lowlat was enabled by default with that kernel.

> and also because I get very noticeable 
> audio dropouts when I do things like task-switch. jackd doesn't report xruns 
> though.

The #1 best thing you can do is mount /tmp as tmpfs.  See the jack
homepage.  It makes all the difference.  Also, if you are using KDE,
Mandrake has this stupid idea of renicing X to -10, which makes the mm
kernel very stop-and-go.  Adjust the -n level to 0 in
/etc/X11/xdm/Xservers.  If you're using gdm (as all sane people do), you
don't have to worry, X is not reniced by gdm.

> Am I correct in thinking that if I start jackd as root I don't need to use -R 
> or jackstart or anything to get good performance? At the moment I think I'm 
> using jackd -d alsa -d hw:0 -p 512 (although that's in a script on my other 
> PC so I might be mis-remembering).

With the mm kernel, you should install jack-realtime, and start jack as
a normal user with 'jackstart'.  That's part of the mm kernel's purpose.

Try using qjackctl too.  It lets you adjust all the jack parameters and
compare the performance.

Austin

-- 
                                 Austin Acton
        Synthetic Organic Chemist, Teaching Assistant, Ph.D. Candidate
               Department of Chemistry, York University, Toronto
        MandrakeLinux Volunteer Developer, homepage: www.groundstate.ca