Re: Context switch times

From: David S. Miller (davem@redhat.com)
Date: Thu Oct 04 2001 - 16:52:39 EST


   From: Richard Gooch <rgooch@ras.ucalgary.ca>
   Date: Thu, 4 Oct 2001 15:39:05 -0600

   David S. Miller writes:
> lat_ctx doesn't execute any FPU ops. So at worst this happens once
> on GLIBC program startup, but then never again.
   
   Has something changed? Last I looked, the whole lmbench timing harness
   was based on using the FPU.

Oops, that's entirely possible...

But things are usually layed out like this:

        capture_start_time();
        context_switch_N_times();
        capture_end_time();

So the FPU hit is only before/after the runs, not during each and
every iteration.

Franks a lot,
David S. Miller
davem@redhat.com
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