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Subject: Re: fiddling with the Opteron - Part II

Author: Russell Reagan

Date: 12:25:43 01/30/04

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On January 30, 2004 at 15:14:40, Mark Rawlings wrote:

>I'm problably missing something, but how can using two processors search to a
>given depth _more_ than twice as fast as one processor?  i.e. 4:52 to get
>through 13 ply for one processor vs. only 1:58 for two processors?  (Maybe there
>is an element of luck as to what gets found in the hash?)

I believe this is due to the fact that multi-cpu search is non-deterministic.
For instance, most simple chess programs will give you the same output under the
same conditions. If I run the 'bench' command in TSCP, it always gives me
exactly the same output on my computer. Running Crafty on an SMP/NUMA machine
will not give you that same consistency. I'm not exactly sure why this happens,
but I'm sure Bob can tell you.



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