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Subject: Re: ponder_on ponder_off comparision

Author: Mogens Larsen

Date: 15:29:34 07/19/00

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On July 19, 2000 at 16:42:13, Robert Hyatt wrote:

>Actually it does.  Because then chessmaster is 100% compute bound and gets
>1/2 of the cpu cycles, where crafty is also 100% cpu bound and gets 1/2 of the
>cycles.  That is about the best way to do this, particularly with so many
>variables among all the different programs...

I believe there was a post concerning Chessmaster problems, where someone
advised against using it in an engine-engine match on a single cpu computer. I
can't remember the exact reason for that warning. It was most likely problems
with ponder=off if what you say is true.

>I haven't seen a recent O/S screw up process scheduling if you have two compute-
>bound processes running concurrently.  In general, each gets 50% which is what
>is supposed to happen.

Yes, that should happen ideally. But since commercial programs, at least Fritz,
use ponder=off on a single cpu machine as "native-mode", I'll stick with that.
I've already stated my other reasons for doing so.

>Some do extrapolate.  IE program X beats program Y 60%-40%.  Someone else
>runs the test and says "I get 50%-50%, why are my results different?"  Then
>you find out that it was a one-cpu match vs a two-machine match.

That kind of examples are very rare. I can't remember anyone doing that, except
for an attempt to check Crafty pondering against Fritz a while back.

>The same problem affects memory.  One machine means you typically "short"
>the programs on hash.  And in the case of Crafty, phash and egtb cache.  Which
>further alters the outcome.

I have 128Mb and use 24+8+3 for Crafty, which is the same values I use for most
programs. The effects are minimal, if they exist at all.

Best wishes...
Mogens



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