Re: v2.6.19-rt6, yum/rpm

[Arjan van de Ven <arjan@infradead.org>]

On Thu, 2006-12-07 at 21:58 +0100, Ingo Molnar wrote:
> * Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU> wrote:
> 
> > Much better performance in terms of xruns with Jackd. Hardly any at 
> > all as it should be. I'm starting to test -rt8 right now.
> > 
> > Now, I still don't have an smp machine to test so the improvement 
> > could be because I'm just running 64 bit up instead of smp. Or it 
> > could have been the hardware on that other machine that had some 
> > problem (either because it was starting to fail or because the kernel 
> > drivers for that hardware were somehow triggering the xruns).
> 
> i think it's the UP vs. SMP difference. We are chasing some SMP 
> latencies right now that trigger on boxes that have deeper C sleep 
> states. idle=poll seems to work around those problems.

well C-states do cause latencies... as advertized in
the /proc/acpi/processor/CPU0/power file.

You can prevent linux from going into c-states that just take too long,
by setting the latency you can tolerate via the
set_acceptable_latency(). You can see the active maximum latency via the
same power file...

(right now audio playback is the main user of this api; of other parts
should use it too lets talk about it)


-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org