[linux-audio-dev] IRQ rotation

[Steve Harris]

On Fri, Mar 05, 2004 at 09:09:31AM -0800, Tim Hockin wrote:
> On Fri, Mar 05, 2004 at 03:06:27PM +0000, Steve Harris wrote:
> > It used to be possible (in the 2.0 kernel series) to the rotate priority of
> > IRQs on the two controllers. This sounds really good as on my laptop the
> > soundcard is welded to IRQ5 (very low priority) and everything else is on
> > IRQ10 (higher, c.f. http://myweb.cableone.net/eviltwin69/Arcana.html sec
> > 2.4), so I can only run the card with big buffers.
> 
> This really mattered?  I'm honestly DEEPLY surprised, and a bit sceptical.
> IRQ priority will only matter AT ALL if you are in a constant state of
> interrupt, or your IRQ handlers are painfully slow, neither of which should
> be true.

Heres /proc/interrupts after ~3 hours of uptime.

           CPU0       
  0:   12578480          XT-PIC  timer
  1:      22347          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  5:          0          XT-PIC  Maestro3
  8:          1          XT-PIC  rtc
 10:      58915          XT-PIC  usb-uhci, ohci1394, eth0, Texas
Instruments PCI4451 PC card Cardbus Controller, Texas Instruments PCI4451
PC card Cardbus Controller (#2)
 11:     774663          XT-PIC  nvidia
 12:      28909          XT-PIC  PS/2 Mouse
 14:      16635          XT-PIC  ide0
NMI:          0 
ERR:          0

Everything beats the soundcard, including the video drivers.

- Steve