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Date: Thu, 04 Oct 2001 14:52:39 -0700 (PDT)
Message-Id: <20011004.145239.62666846.davem@redhat.com>
To: rgooch@ras.ucalgary.ca
Cc: arjan@fenrus.demon.nl, kravetz@us.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: Context switch times
From: "David S. Miller" <davem@redhat.com>
In-Reply-To: <200110042139.f94Ld5r09675@vindaloo.ras.ucalgary.ca>
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	<20011004.142523.54186018.davem@redhat.com>
	<200110042139.f94Ld5r09675@vindaloo.ras.ucalgary.ca>
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   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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