linux-kernel - Re: 2.6.19-rc6-rt8: alsa xruns

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Date:	Tue, 28 Nov 2006 21:09:27 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Fernando Lopez-Lezcano <nando@...ma.Stanford.EDU>
Cc:	"Linux-Kernel," <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.19-rc6-rt8: alsa xruns


* Fernando Lopez-Lezcano <nando@...ma.Stanford.EDU> wrote:

> Hi, I'm trying out the latest -rt patch and getting alsa xruns when 
> using jackd and jack clients. This is a sample from the output of 
> qjackctl / jackd (jack 0.102.25, qjackctl 0.2.21):

> (            japa-4096 |#0): new 17 us maximum-latency wakeup.
> (         beagled-3412 |#1): new 19 us maximum-latency wakeup.
> (          IRQ 18-1081 |#1): new 26 us maximum-latency wakeup.
> (             snd-4040 |#1): new 1107 us maximum-latency wakeup.
> (            japa-4096 |#0): new 1445 us maximum-latency wakeup.
> (            japa-4096 |#0): new 2110 us maximum-latency wakeup.
> (        qjackctl-4038 |#1): new 2328 us maximum-latency wakeup.
> (            japa-4096 |#0): new 2548 us maximum-latency wakeup.
> (          IRQ 18-1081 |#0): new 10291 us maximum-latency wakeup.

hm, lets fix this. Could you enable tracing (on the yum rpm) via:

	echo 1 > /proc/sys/kernel/trace_enabled

does /proc/latency_trace have any meaningful events included for such a 
long delay? If not then it would be nice to rebuild the kernel with 
CONFIG_LATENCY_TRACING - and in any case my previous suggestion holds 
too: booting with maxcpus=1 to reproduce the latencies will give easier 
to interpret latency traces. (but if it's SMP-only then no problem, the 
latency traces are still valuable)

	Ingo
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