Re: userspace irq balancer

David S. Miller
2003-05-27T01:09:02Z

From: Dave Jones <davej@codemonkey.org.uk>
Date: Tue, 27 May 2003 02:16:20 +0100

On Tue, May 27, 2003 at 03:09:03AM +0200, Andrea Arcangeli wrote:

> rdtsc could do it very well, irqs and softirqs can't be rescheduled so
> you can tick measure how long you take in each cpu

On CPUs that vary frequency, this will break, unless TSC scales
with frequency. You cannot assume that this will be the case.

This is an important issue, for another reason.

The networking packet scheduler layer wants an accurate (but
cheap) high frequency time source too.

I keep forgetting to go back and deal with fixing up all of
those hairy macros in pkt_sched.h, I've added this to my TODO
list.