Subject: Re: [linux-audio-user] Low latency kernel on Mandrake
From: Austin (aacton_AT_yorku.ca)
Date: Mon Nov 03 2003 - 01:07:44 EET
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
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