Re: [Jack-Devel] ALSA PCM multi plugin and xruns

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DateMon, 10 Dec 2012 18:41:04 +0000
From John Rigg <[hidden] at jrigg dot co dot uk>
To[hidden] at lists dot jackaudio dot org
In-Reply-ToDevin Anderson Re: [Jack-Devel] ALSA PCM multi plugin and xruns
Follow-UpJohn Rigg Re: [Jack-Devel] ALSA PCM multi plugin and xruns
Follow-UpJohn Rigg Re: [Jack-Devel] ALSA PCM multi plugin and xruns
On Sun, Dec 09, 2012 at 09:17:42PM -0800, Devin Anderson wrote:
> I modified the CPU affinity of the IRQs of the two Layla 3Gs so that
> they are only handled by one CPU, and modified the `irqbalance`
> configuration so that it doesn't modify the CPU affinity settings for
> the IRQs of the Layla 3Gs, and so that it doesn't use the CPU handling
> the Layla 3G interrupts for other interrupts.
> 
> I haven't been able to trigger the onslaught of xruns in the past
> hour, and I'm doing the same things that produced the xruns before
> within 5 minutes or so.
> 
> @John (and anyone else experiencing tons of xruns with an ALSA PCM
> multi setup): I suggest that you make the same modifications to your
> system, and see if the problem goes away.  If you need any assistance,
> let me know.

I've tried smp_affinity here and it hasn't fixed the problem. It just
took longer for the xrun messages to show up.

I set the smp_affinity for the two ice1712 cards (which are on IRQ20
and 21) to CPU1 in my test system with the following:
echo "2" > /proc/irq/20/smp_affinity
echo "2" > /proc/irq/21/smp_affinity

Then I started jackd with my pcm_multi device at 96kHz and started
jamin to generate some load. At first it looked like this had worked,
but after about 5 minutes the xrun indications in jamin started piling
up. Both IRQs are definitely handled by CPU1 according to frequent
checks using cat /proc/interrupts.

My test system uses an AMD 4850e Athlon64x2 2.5GHz CPU. Running jamin at
96kHz uses 11% CPU according to jamin's load indicator.

John
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