Re: [patch] voluntary-preempt-2.6.8-rc2-M5

Ingo Molnar
2004-08-01T11:29:11Z

On Fri, 30 Jul 2004, Lee Revell wrote:

> Results with 2.6.8-rc2-M5:
>
> Configuration max usecs
> -----------------------------------------------------------------
> All IRQs threaded 370
> Soundcard IRQ not threaded 335
> Soundcard IRQ not threaded + max_sectors_kb -> 64 161
>
> So, it looks like the added configurability does add some overhead - 161
> usecs vs. 50. [...]

+110 usecs is too much to be explained by redirection and configurability
overhead. The configurability overhead is near zero.

could you try to repeat the '50 usecs' test with -L2 [that was the one you
used?] to make sure it's repeatable? The latencies of -L2 and -M5 should
be near identical. The configurability should at most cause a 1-2 usecs
overhead - definitely not two orders of magnitude higher. So if there's a
difference then i must have degraded one of the latency reduction changes
between L2 and M5.

Ingo