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Subject: Re: [patch] voluntary-preempt-2.6.8-rc2-L2, preemptable hardirqs
From: Thomas Charbonnel <thomas@undata.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Lee Revell <rlrevell@joe-job.com>,
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> * Thomas Charbonnel <thomas@undata.org> wrote:
> 
> > The other source of xrun was seen during the disk write tests, once
> > the memory runs out (spikes up to 14 ms, but more generally 6 ms)
> 
> which particular filesystem and disk driver are you using? (ext3/IDE?) 
> The 'disk write tests' are those of latencytest-0.5.4?
> 
> 	Ingo

It's an IDE reiserfs disk.
Those are indeed the disk write tests from latencytest-0.5.4
My mistake about the spikes, they are more 3 ms than 6.
You can see the results here :
http://www.undata.org/~thomas/latencytest-0.5.4/rtc_freq_2048/
http://www.undata.org/~thomas/latencytest-0.5.4/rtc_freq_4096/
http://www.undata.org/~thomas/latencytest-0.5.4/rtc_freq_8192/

The traces always look the same : 

T=29.6014 diff=14.4758
 rtc_interrupt (+bd)
 handle_IRQ_event (+50)
 do_hardirq (+bc)
 irqd (+ac)
 kthread (+aa)
 irqd (+0)
 kthread (+0)
 kernel_thread_helper (+5)


Thomas