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Subject: Re: A Strange Result, A P-IV at 1.7 Ghz Outperforms an Athlon at I.4 Ghz!

Author: Tony Werten

Date: 23:49:14 01/20/02

Go up one level in this thread


On January 21, 2002 at 00:04:50, Terry McCracken wrote:

>On January 20, 2002 at 23:43:21, Vincent Diepeveen wrote:
>
>>On January 20, 2002 at 22:02:10, Terry McCracken wrote:
>>
>>>Can anyone explain how and why a P-IV at 1.7 Ghz with 512MB (PC800) RDRAM
>>>outperformed an Athlon running at 1.4 Ghz with 266Mgh DDR Bus and 256MB of SDRAM
>>>on a Fritzmark by a wide margin?
>>
>>fritz might be in p3 assembly and has probably nearly no mispredicted
>>branches somehow. further it is such a small program that it hardly
>>needs data cache.
>>
>I'm not sure what you mean that Fritz is a small programme compared to other
>chess software? If that is so, then why is Fritz at the head of it's class
>compared to other commercial programmes most of the time wich you say need more
>cache and are larger programmes?

On the knowledge vs speed graph, Fritz has always been on the speed side. It
says nothing about the quality of the program, it's a design choice.

And it's a circular reasening:

You want high speed so you make your evaluation a bit smaller, you know you will
know a bit less about every position than other programs and you compensate that
by searcher deeper. To achieve that start at the beginning of this sentence.

OR

You want extensive evaluation so you make your evaluation a bit bigger. You know
you will search a bit less deep than other programs and you compenate that by
knowing more about each position. To achieve that start at the beginning of this
sentence.

Tony

>
>>The 3 major disadvantages from the P4 are
>>  a) HUGE branch misprediction penalty
>>  b) very SMALL datacache
>>  c) no way to do 4 instructions a second according to
>>     experts who read the design, it can to at most 3
>>     instructions a second.
>>
>
>Well this was a P-4 vs Athlon, _not_ a P-3. So optmization for a P-3 would have
>no bearing in this case. I find much of the data about the P-4 at this site very
>suspect.
>There appeared to be no serious branch misprediction, and it flew past the
>Athlon chip.
>>>
>
>The Fritzmark for the Pentium was 749 and the AMD a mere 548! Why? This is
>>>contrary to the findings of this forum. That is a difference of 201, that is
>>>large!
>>>
>>>An explantion would be appreciated, thanks!
>>>
>>>Terry



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