Re: [LAU] Ubuntu: changing realtime priority of irqs

From: David Causse <nomoa@email-addr-hidden>
Date: Sat Jul 21 2007 - 17:03:24 EEST

Atte André Jensen a écrit :
> Hi
>
> I trying out ubuntu with ubuntustudio kernel. In debian I always set the
> priority of the IRQ's using
>
> chrt -f -p 85 `pidof "IRQ 8"`
>
> However that doesn't work in ubuntu. The reason is that there seems to
> be no process named "IRQ 8":
>
> atte@email-addr-hidden:~$ ps aux | grep -i IRQ
> root 3 0.0 0.0 0 0 ? SN 13:43 0:00
> [ksoftirqd/0]
> atte 6274 0.0 0.0 2884 772 pts/0 R+ 13:51 0:00 grep -i
> irq
>
Hi,

Your ubuntu kernel doesn't support this feature, to be sure try to look
at /proc/config.gz
zcat /proc/config.gz | grep PREEMPT

You must have something like this :
CONFIG_PREEMPT_HARDIRQS=y

It appears that the default kernel used by Ubuntu studio
(linux-image-lowlatency) is not patched against the Ingo's RT patch
(required to do what you want)
http://www.mail-archive.com/debian-multimedia@email-addr-hidden/msg01756.html
The RT kernel package seems to be linux-image-2.6.21-1-multimedia-486
<http://apt.64studio.com/64studio/testing/pool/main/l/linux-2.6/linux-image-2.6.21-1-multimedia-486_2.6.21-2_i386.deb>

David C.

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Received on Sat Jul 21 20:15:02 2007

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