Re: do_gettimeofday vs. rdtsc in the scheduler

David S. Miller (davem@redhat.com)
Tue, 17 Sep 2002 13:54:51 -0700 (PDT)


From: Andi Kleen <ak@suse.de>
Date: 17 Sep 2002 23:00:38 +0200

Also reading HPET is somewhat more costly than reading TSCs because it
goes to the southbridge, so there are cases where using TSC is
probably better (e.g. I think for networking packet time stamping the
TSC is just fine with all its limitations)

The cpu gets a bus clock input, so the system tick should be processor
local as much as TSC is.

It's boggling that this is being messed up so much. I can't believe
Sun got something incredibly right (Ultra-III has a system tick) :-)
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