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Date: Sun, 21 Nov 2004 15:49:44 +0100
From: Florian Schmidt <mista.tapas@gmx.net>
To: Ingo Molnar <mingo@elte.hu>
Cc: Lee Revell <rlrevell@joe-job.com>, linux-kernel@vger.kernel.org,
       Rui Nuno Capela <rncbc@rncbc.org>, Mark_H_Johnson@Raytheon.com,
       "K.R. Foley" <kr@cybsft.com>, Bill Huey <bhuey@lnxw.com>,
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       Fernando Pablo Lopez-Lezcano <nando@ccrma.Stanford.EDU>,
       Karsten Wiese <annabellesgarden@yahoo.de>,
       Gunther Persoons <gunther_persoons@spymac.com>, emann@mrv.com,
       Shane Shrybman <shrybman@aei.ca>, Amit Shah <amit.shah@codito.com>
Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.29-0
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On Sun, 21 Nov 2004 13:45:55 +0100
Ingo Molnar <mingo@elte.hu> wrote:

> 
> * Florian Schmidt <mista.tapas@gmx.net> wrote:
> 
> > > Will build 29-4 PREEMPT_REALTIME now and see how this one behaves.
> > 
> > Pretty much as bad as 29-1. Sadly i have no idea on how to find out
> > what is causing jackd to act so weird under a PREEMPT_REALTIME kernel.
> > It seems there is some correlation to activity on X. Hiding and
> > showing windows has a certain chance of triggering a large xrun.
> 
> do you have chrt-ed the IRQ#0 thread and the soundcard thread as well?

yes. I tried the following combinations with PREEMPT_RT:

- IRQ 0 prio 40, IRQ 3 (soundcard) prio 98
- IRQ 0 prio 99, IRQ 3 prio 98

all other IRQ's at prios around 40-50 (default or set explicitly to 40).
What is the recommended setting for IRQ 0? I thought in this typical
thread-wakeup-by-IRQ scenario the scheduler is "shorted" anyways when an IRQ
occurs, so IRQ 0's prio shouldn't really matter.

flo