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

[Jeremy Jongepier]

On 05/03/12 08:25, Fernando Lopez-Lezcano wrote:
>
> For soundcard drivers there is no convention for naming the irq process
> that services its interrupt. The name of the irq process does not match
> the name of the kernel module (which would be an obvious choice). The
> ascii that is printed by ps is defined in the kernel code for each
> driver, and driver authors pick different names that are not consistent.
> That means you can't pattern match for the right irq process if the
> interrupt number is shared by several devices.
>
> It would be possible to pattern match if, for example, all soundcards
> used a "snd_" prefix for the name of the irq process, but that is not
> the case (at least until last time I looked at the kernel code for this
> very same reason).
>

I wasn't aware of that, thanks.

>> So the graphics card gets a
>> label 18-nvidia, the soundcard 18-snd_hdsp and both usb hubs
>> 18-ohci_usb. And it is those labels that rtirq uses to set the rtprio
>> for the different softirqs.
>
> The rtirq code does the following (simplified):
>
> - rtirq gets the irq number from /proc/asound/cards

Afaics rtirq only does this if a pattern in RTIRQ_NAME_LIST matches 
'snd'. In all other cases (like you point out later too) everything 
passes through the rtirq_exec_name function first which greps on 
/proc/interrupts.

Best,

Jeremy