Re: [linux-audio-dev] IRQ rotation

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Subject: Re: [linux-audio-dev] IRQ rotation
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Fri Mar 05 2004 - 20:30:58 EET

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

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