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Subject: Re: Single Processor vs Dual Processors

Author: Robert Hyatt

Date: 20:16:13 04/27/98

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On April 27, 1998 at 18:41:55, Amir Ban wrote:

>On April 27, 1998 at 16:30:34, Rajen Gupta wrote:
>
>>Dear Bob
>>
>>Which would be stronger-Crafty playing on a Single Pentium 400 MHZ
>>System vs  Crafty playing on a dual processor system consisting of 2
>>Pentium 200MMX(or Pentium Pro 200 x2)ie does a single processor system
>>running at N megahertz play better chess than a dual processor system
>>running on 2 xN/2 processors?
>>
>>rajen gupta
>
>That is trivially true. To see this, consider that the faster processor
>can divide its time to simulate a two-processor algortihm.
>
>Practically, there is always significant waste of processor time when
>doing parallel processing for alpha-beta. What is the best efficiency
>achieved yet ?
>
>Amir



So far as I know, probably Cray Blitz.  It was almost 12X faster using a
16 processor machine...  and that is hard to do.

But given a choice of two PII/200 processors or 1 PII/400, I would
likely
take the PII/400, assuming memory and everything is not hosed up.  It is
*very* difficult to go 2x faster.  The tests I have done on Crafty seem
to
show an average of 1.5X to 1.75X faster than one processor.  4
processors
is around 3.25 X faster at present...

However, when you think about it, there are some *interesting* boxes
running around... I wouldn't think 10M nodes per second would be
difficult
at all...  running on a big multiprocessor alpha like the Cray T3E...

or even 2-3M nodes per second on a stock alpha multiprocessor...



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