[LAU] Realtime priority when using several cards as MIDInterface

[Ralf Mardorf]

I'm using a RME card for audio and MIDI and two Envy24 cards for MIDI.

Using rtirq with it's default in /etc/rtirq.conf,
resp. /etc/default/rtirq resp. /etc/sysconfig/rtirq

RTIRQ_NAME_LIST="rtc snd usb i8042"

caused

PID CLS RTPRIO  NI PRI %CPU STAT COMMAND 
 55 FF      90   - 130  0.0 S    irq/8-rtc0      
659 FF      85   - 125  0.0 S    irq/20-ICE1712  
671 FF      85   - 125  0.0 S    irq/21-ICE1712  
652 FF      83   - 123  0.1 S    irq/18-hdspm

switching to

RTIRQ_NAME_LIST="rtc hdspm snd usb i8042"

resulted in

PID CLS RTPRIO  NI PRI %CPU STAT COMMAND      
 55 FF      90   - 130  0.0 S    irq/8-rtc0   
619 FF      85   - 125  0.1 S    irq/18-hdspm 
629 FF      80   - 120  0.0 S    irq/20-ICE1712       
631 FF      80   - 120  0.0 S    irq/21-ICE1712

Dunno, perhaps RTIRQ_NON_THREADED="rtc snd" should also be edited.

Anyway, thanks to coincidence I noticed this issue and thanks to Rui I
was able to correct the priority.

My intend is to inform users of several PCI, PCIe MIDInterfaces to take
care about priorities, when one of the devices additionally is used for
audio too.

I didn't test if there's an audible difference on my machine, I suspect
that there isn't any difference, but IMO even this could be the cause
for an issue.

FWIW, I also own an USB MIDI device, a nice addition for non-rt bulk
dump, for my needs useless to make music.

I guess if I wouldn't use those Envy24 cards as MIDInterfaces, the RME
would have first priority after the clock.

- Ralf