Re: [Jack-Devel] Some kernel questions reg. jack

On 17/02/12 22:07, Ede Wolf wrote:
> I do have some questions regarding kernel options for a jack friendly
> kernel. I've found some information on the net, some outdated, some
> maybe not complete. I am talking about a stock vanilla kernel 3.2 with
> BFS scheduler, I most likely do not need hard realtime.

I found that the sound card you use has a lot to do with it.  I 
drastically reduced XRUNs by getting a new sound card.  This helped much 
more than any kernel options I tried.  I had a Soundblaster Live 24-bit 
before (was OK latency wise), as well as onboard auduio (not very good 
latencies).  I then got a Xonar D1 and don't have latency problems anymore.

I use BFS too, btw.  An RT kernel didn't help much.


> So a 1000Hz timer and full preemption are quite obvious. A tickless
> system is not recommended, IIRC and also hyperthreading should be
> disabled in bios as well as kernel? Same with Power management, I suppose.

Tickless and HT are fine.  Power management can be tweaked at runtime, 
no need to disable it in the kernel.  You can switch your CPU(s) to 
performance mode with:

   cpufreq-set -r -g performance

You can see what the current mode is with:

   cpufreq-info


> Finally, not really kernel related, but what is about irq-balancer? I've
> attached "threadirqs" to my lilo line - there is no dedicated kernel
> option for threadirqs? - do threadirqs and irq-balancer they play well
> together or should latter one be removed?

Don't know about irq-balancer, but threadirqs definitely helps here with 
XRUNs.

1329689768.2692_0.ltw:2,a <jhrsa8$p4o$1 at dough dot gmane dot org>