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

On Saturday 21 July 2007, Atte André Jensen wrote:
> 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
>
> Whereas on debian I would get:
>
> atte@email-addr-hidden:~$ ps aux | grep IRQ
> root 18 0.2 0.0 0 0 ? S< 13:34 0:00 [IRQ 9]
> root 261 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ 4]
> root 286 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ
> 12]
> root 300 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ 1]
> root 608 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ
> 11]
> root 761 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ
> 14]
> root 787 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ
> 15]
> root 1592 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ 8]
> root 1593 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ 7]
> root 1683 0.0 0.0 0 0 ? S< 13:34 0:00 [IRQ
> 10]
> atte 4672 0.0 0.0 2848 704 pts/1 R+ 13:41 0:00 grep
> IRQ
>
> I suspect it has something to do with "ksoftirqd" which according to the
> man page seems to be a daemon handling irqs.
>
> http://tapas.affenbande.org/wordpress/?page_id=40 also doesn't seem to
> take ksoftirqd into account.
>
> So my question is: How do I set the priorities in ubuntu? Is it
> possible/clever/stupid to get rid og ksoftirqd and get things working
> the way I'm used to under debian, and if so how?

No, ksoftirq shouldn't have anything to do with it.. HEre's what the output of
that is on my system:

~$ ps aux|grep IRQ
root 41 0.0 0.0 0 0 ? S< Jul21 0:00 [IRQ-9]
root 775 0.0 0.0 0 0 ? S< Jul21 0:00 [IRQ-8]
root 812 0.0 0.0 0 0 ? S< Jul21 0:09 [IRQ-12]
root 813 0.0 0.0 0 0 ? S< Jul21 0:00 [IRQ-1]
root 2032 0.0 0.0 0 0 ? S< Jul21 0:00 [IRQ-16]
root 2110 0.0 0.0 0 0 ? S< Jul21 0:00 [IRQ-17]
root 2152 0.0 0.0 0 0 ? S< Jul21 0:03 [IRQ-14]
root 2192 0.0 0.0 0 0 ? S< Jul21 0:02 [IRQ-15]
root 2745 0.4 0.0 0 0 ? S< Jul21 3:42 [IRQ-18]
root 3629 0.0 0.0 0 0 ? S< Jul21 0:00 [IRQ-7]
root 3785 0.1 0.0 0 0 ? S< Jul21 0:55 [IRQ-19]
tapas 14252 0.0 0.0 2884 752 pts/1 R+ 01:35 0:00 grep IRQ

~$ uname -a
Linux balabala 2.6.20-16-realtime #2 SMP PREEMPT Fri Jun 15 04:43:25 CEST 2007
i686 GNU/Linux

Let's see your uname -a output please..

Flo

-- 
Palimm Palimm!
http://tapas.affenbande.org
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