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From: Bill Davidsen <davidsen@tmr.com>
To: Larry McVoy <lm@bitmover.com>
Cc: "David S. Miller" <davem@redhat.com>,
	mau@oscar.prima.de, linux-kernel@vger.kernel.org
Subject: Re: LMbench results for 2.5.40
Date: Tue, 8 Oct 2002 14:55:01 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.3.96.1021008144209.5056D-100000@gatekeeper.tmr.com> (raw)
In-Reply-To: <20021001163757.J13270@work.bitmover.com>

On Tue, 1 Oct 2002, Larry McVoy wrote:

> By the way, the place you will probably see variance in LMbench is in the
> context switch benchmarks, it's almost certainly due to randomness in 
> cache layout and there isn't a thing we can do about it.  You can run a
> zillion runs to get an average but please realize that is an *average*.
> The context switch number are accurate, the low ones represent no cache
> collisions and the high ones represent lots of cache collisions.
> 
> FYI.  I don't like it either.

Thank you, that explains some things I've seen in my context switching
benchmark as well, which uses a bunch of different services to transfer
tiny data from on process to another.

Time for some statistical jiggery-pokery, dust off deviant mean or some
such.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.


  reply	other threads:[~2002-10-08 18:58 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-10-01 22:08 LMbench results for 2.5.40 Patrick Mau
2002-10-01 22:16 ` Jeff Garzik
2002-10-02 17:33   ` Patrick Mau
2002-10-08 19:04     ` Bill Davidsen
2002-10-02 17:38   ` Patrick Mau
2002-10-01 23:15 ` David S. Miller
2002-10-01 23:37   ` Larry McVoy
2002-10-08 18:55     ` Bill Davidsen [this message]
2002-10-08 19:07       ` Larry McVoy
2002-10-10 13:21         ` Bill Davidsen

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