[LAU] Issue with the priority of the sound cards using rtirq

[Fernando Lopez-Lezcano]

On 05/03/2012 10:00 AM, Fernando Lopez-Lezcano wrote:
> The failure is because there is (as I pointed out) no fixed greppable
> relationship between the textual information found in /proc/asound/cards
> and the names of the processes that service the interrupts - I have
> looked at the relevant kernel code and the names of the processes are
> arbitrary strings.

Some good news! Something has changed from 2.6.33 to 3.2.x...

This finds all irq setup calls on the 3.2 kernel tree:

   find sound/ -type f -exec grep -2 request_irq {] \; -print

The fourth argument to that call is what is going to be shown in the ps 
listing. Now, I found that all _pci_ cards in 3.2.x have KBUILD_MODNAME 
as the fourth argument (that was not the case before!). So anything 
starting with "snd_" is going to be a soundcard, so rtirq could have 
another special case for that.

Rui: this addition/hack in rtirq takes care of snd_hda_intel in my 
3.2.16-rt27 system and will presumably do the right thing for any other 
pci soundcards:

----
		# Special for kernel-rt >= 2.6.31, where one can
		# prioritize shared IRQs by device driver (NAME2)...
	        # first try with irq names that start with snd_
	        PIDS=`ps -eo pid,comm | egrep -i "IRQ.${IRQ}.snd_.*" | awk 
'{print $1}'`
		if [ -n "${PIDS}" ]
		then
		    RTIRQ_TRAIL=":${IRQ}${RTIRQ_TRAIL}"
		else
		    # try with the name reported in /proc/asound/cards
		    PIDS=`ps -eo pid,comm | egrep -i "IRQ.${IRQ}.${NAME2:0:8}" | awk 
'{print $1}'`
		    if [ -n "${PIDS}" ]
		    then
			RTIRQ_TRAIL=":${IRQ}${RTIRQ_TRAIL}"
		    else
			# Backward compability for older kernel-rt < 2.6.31...
			PIDS=`ps -eo pid,comm | egrep -i "IRQ.${IRQ}" | awk '{print $1}'`
			if [ -n "${PIDS}" ]
			then
			    RTIRQ_TRAIL=":${IRQ}${RTIRQ_TRAIL}"
			fi
		    fi
                 fi
----

far from a solution, this is a list of sound/ subdirectories in 3.2 
where this does not hold true:

sound/ppc/
sound/mips/
sound/oss/
sound/arm
sound/sparc/

sound/spi
sound/soc
sound/parisc
sound/pcmcia/
sound/isa/
sound/drivers/
sound/atmel/
sound/aoa/

but it will work for a LOT of frequently used soundcards, at least when 
running 3.2 ...

-- Fernando