Re: [patch] voluntary-preempt-2.6.8-rc2-L2, preemptable hardirqs

Lee Revell
2004-07-28T21:50:41Z

On Wed, 2004-07-28 at 01:05, Ingo Molnar wrote:
> * Lee Revell <rlrevell@joe-job.com> wrote:
> if your soundcard doesnt share the irq line with any other 'heavy'
> interrupt then you can make the irq 'direct' via a simple change to
> arch/i386/kernel/irq.c, change this line from:
>
> #define redirectable_irq(irq) ((irq) != 0)
>
> to:
>
> #define redirectable_irq(irq) (((irq) != 0) && ((irq) != 10))
>
> (if the soundcard is on IRQ 10).
>
> does such a change combined with v=3 fix the latencies you are seeing?

With L2, 1:3, max_sectors_kb=256, and the above change, the performance
is truly amazing. Over 20 million interrupts, on a 600Mhz machine, the
worst latency I was able to trigger was 46 usecs. There does not seem
to be any adverse affect on any aspect of the system.

This looks like the perfect setup for a DAW.

Lee