[LAD] MidiSport vs. UA25

Arnout Engelen lad at bzzt.net
Sat Sep 26 12:07:57 UTC 2009

On Sat, Sep 26, 2009 at 01:29:53PM +0200, Ralf Mardorf wrote:
> Arnout Engelen wrote:
>> - increased the rtprio for the USB IRQ handler
> How can I do this? I only know how to make my Siwssonic USB MIDI device  
> head of the USB devices by Rui's rtirq.
> Is there something I could change for rtirq, to get less jitter for the  
> USB MIDI device?

I haven't looked into rtirq yet (I really should), but if I understand 
correctly rtirq does automatically what I did manually: find out which IRQ 
the device you're interested in is connected to, and give that IRQ a 
higher rtprio.

To see the current rtprio's of your IRQ's, do:

  ps axHo user,lwp,pid,rtprio,ni,command | grep irq

To increase the rtprio of some irq manually:

  chrt -f -p <prio> <pid>

>> - decreased the 'latency_timer' value for my wireless network card and cardbus
>>   slot
>> - tried to increase 'latency_timer' for the USB controller, but it 
>> remained at 0 - i guess it doesn't support this option
> *?*



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