[linux-audio-user] realtime-preempt-2.6.11-rc1-V0.7.35-01

[Matthew Allen]

On Sun, 16 Jan 2005 20:28:24 +0100, Florian Schmidt <mista.tapas at gmx.net> wrote:
> 
> > There is a link on the wiki about setting irq priorities, but it seems
> > to be broken. How do I set these? and how do I set SCHED_FIFO for an irq
> > handler?
> 
> Hmm, "irq priorities" are something different from "irq handler
> priorities". The former refers to the priorities on the interrupt
> controller. Usually messing with these is not needed, especially on RP
> kernels, as the top level irq handler routines are very short.
> 
> What we want to control is the priority of the bottom half irq handler
> which is doing the grunt work. For this, the chrt utility from the
> schedutils package is useful..
> 
> chrt -f -p 99 `pidof "IRQ 5"`
> 
> for example, makes the bottom half irq handler for IRQ 5 run SCHED_FIFO
> with a priority of 99. Inspect the output of
> 
> cat /proc/interrupts
> 
> to see which irq number corresponds to which device..
> 
> Use
> 
> chrt -p `pidof "IRQ 5"`
> 
> to inspect the scheduler classes and priorities for irq's..
> 

This is essentially what Rui's rtirq script does, based on some user input.

Florian, I noticed your wiki was locked. It would be great to get some
of the up to date info up somewhere (mostly the RT preempt stuff). I
was about 1/2 through writing a gentoo how-to when I realized it was
much more generic (and most of this stuff isnt in portage anyway). Is
there a way to sey up the wiki with a generic lad password?  The way
the RT stuff (and the kernel in general) has changed and evolved in
the last 6 months seems to say we need a doc for this stuff thats
really living.