rtirq, limits.conf and hardware/software priorities

  • ethanay
Posted: Thu, 06/12/2008 - 10:40
according to http://freebob.sourceforge.net/index.php/IRQ_Threading_and_Priorities hardware priorities should be higher than software priorities. I am assuming that /etc/default/rtirq deals with hardware, while /etc/security/limits.conf deals with software. Is this correct? If so, wouldn't it make sense to set the max priority in the limits.conf lower than the max priority of rtirq? If not, how do you go about a) viewing and b) setting software priorities to ensure that jackd has a lower priority than the hardware priorities set by rtirq, and that other audio software priorities are lower than jackd (but still higher than everything else)? And now, for the golden question: is this taken care of "out of the box" in 64studio? :) (even if it is, I still want to understand!) Looking forward to a good discussion :)

"the top" of top

  • ethanay
  • 05/20/08
  • Thu, 06/12/2008 - 19:57
yes, jackd seems to be running at the top of top all the time, with other audio apps (good). But that indicates resource usage, right? While the columns PR (+value = high priority) and NI (-value = high priority) are more the actual priority level? My understanding is PR is the normal priority level -- the default. While NI is the value which sets how easily the process can interrupt other processes to complete work it needs to do, even if it normally has a lower priority... So it is possible that a high priority process wouldn't show up in top or at least near the top because it is not an intensive user of system resources...? This confused me at first -- I thought the hardware should be listed at the top if I had set things up properly, but I don't think this is the case!

You can check priorities

  • Quentin Harley
  • 05/24/07
  • Thu, 06/12/2008 - 10:48
... of running tasks by running "top" in a terminal. on my system the irqs have negative values, making the priority very high.