Re: [linux-audio-user] Problems appling realtime preempt patch to 2.6.12 (general)

From: Eric Dantan Rzewnicki <rzewnickie@email-addr-hidden>
Date: Wed Jul 13 2005 - 18:09:38 EEST

On Tue, Jul 12, 2005 at 01:46:13PM -0700, Fernando Lopez-Lezcano wrote:
> On Tue, 2005-07-12 at 12:56, Iain Duncan wrote:
> > >>I've just joined the list and it's pretty interesting.
> > >>Can someone tell me something about the differences between the
> > >>preempt patch from Ingo and the "Realtime Linux Security Module"?
> > >>I currently use the latter one and I'm quite satisfied as jack works
> > >>really fast. Perhaps one should try this way instead of the vanilla
> > >>kernel patch. There have to be pros and cons I'm interested in. Can
> > >>someone point them out?
> > > The LSM and Ingo's patches are addressing 2 separate issues. Ingo's
> > > patch is working to minimize sources of latency in various code paths in
> > > the kernel. The rtlimits and the realtime-lsm are addressing the issue
> > > of providing a security model for realtime applications to get the
> > > capabilities they need to run in real-time. Ordinarilly these
> > > capabilities (CAP_SET_PCAP, mlockall(), and SCHED_FIFO()) are only
> > > accessible as root. rtlimits and the realtime-lsm provide infrastructure
> > > for allowing these capabilities to be granted to only a specified set of
> > > users/processes.
> > So am I correct in believing that the preempt patch is the one that
> > makes a difference if I intend to run as root anyway?
> It makes (should make?) a difference independent of whether you run as
> root or not. If you run as root you can access everything. If you don't
> run as root (highly recommended :-) you need some additional stuff to
> get the same performance.
> > ( Yeah I know I'm
> > not supposed to, but IMO my machine is just a synthesizer in disguise as
> > a computer and I'll unplug the ethernet cable if I need to. )
> 2.6.12 already includes the rlimits patch that will allow you to run
> well as a non-root user. But you will need a patch to pam (if your
> distro uses pam) or a special user program to access realtime scheduling
> as a non-root user (was posted not long ago to this list).

I vaguely recall that demudi stuck with the realtime-lsm for the current
version. Is this correct?

Are there deb packages of the patched pam available?
what about rpm's for ccrma?

Eric Dantan Rzewnicki  |  Systems Administrator
Technical Operations Division  |  Radio Free Asia
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Received on Wed Jul 13 20:15:24 2005

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