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

On Sa, 21.07.07 14:03 Atte André Jensen <atte.jensen@email-addr-hidden> 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":

I only get processes for IRQ's on -rt patched kernels
Maybe ubuntustudio uses a standard patched-to-death ubuntu kernel with
hz 1000 and LLD preempt?

> 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?
>
> --
> peace, love & harmony
> Atte
>
> http://atte.dk | http://myspace.com/attejensen
> http://anagrammer.dk | http://atte.dk/compositions
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