[Fwd: Re: [PD] Low Latency patch for kernel 2.6.8.1 anyone?]

[Aymeric]

and a little note from ck's site about preemption in 2.6 for those who
still wonder if they should use it or not.

"Preempt?
I recommend disabling preemption in the kernel configuration unless you
have a specific low latency requirement! It causes poorly written
applications to misbehave far more. The gains in lateny with in-kernel
preemption in 2.6 would not be noticable to a human, unlike 2.4 which
had much larger latencies in the kernel. For serious audio work, video
capture etc, you should enable preempt."

http://members.optusnet.com.au/ckolivas/kernel/

and interesting articles about preempt or not (so now you can get even
more confused)

http://kerneltrap.org/node/view/2702

http://kerneltrap.org/node/view/3440


+!
aym3ric.

ps: maybe it would be nice "one day" to try to gather pd "benchmarks" to
see what the best could be taken from 2.6 kernels and how, everytime a
latency talk is started it's always dying into mass-confusion. I think
it would be really great to have online somewhere, a kernel
recommandation guide for pd that has not be written for 2.4 and planet
ccrma (no offense, just looking for fresh docs).

ps: i'm aware such talks are mostly happening in linux-audio lists, but
my point here is to make this whole information friendly available for
users, as a single note about recommanded software setup. This could be
even extended to Gem and pdp/pidip, pointing on which drivers are the
most efficient etc etc ... just a simple "pd setup guideline".



On Mon, Sep 06, 2004 at 01:19:50PM +1000, Luke Yelavich wrote :
> On Mon, Sep 06, 2004 at 03:36:53PM EST, Ian Smith-Heisters wrote:
> > Isn't low latency part of the kernel as of 2.6? If it's not 
> > automatically turned on, it's an option in the config. I guess I'm 
> > assuming you're talking about THE low latency patch that we used to use 
> > on 2.4, but perhaps you're looking for any new low latency patches...?
> 
> You are thinking of the preemptable kernel config option. Unfortunately, wit
> this option turned on, it is still not possible to get as low a latency as it
> is on 2.4. There is however, a patch that is being worked on to address this
> issue, and while it is quite stable now, it still has some way to go, as more
> problems are being found all the time.
> 
> Check out the following URL for more info.
> 
> http://www.affenbande.org/~tapas/linux-2.6.x-ll.html
> -- 
> Luke Yelavich
> http://www.audioslack.com
> luke at audioslack.com
> 
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