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Subject: Re: Is more hash better? My tests say the opposite...

Author: Tony Werten

Date: 05:55:51 09/01/03

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On September 01, 2003 at 04:28:04, Ed Schröder wrote:

>On August 31, 2003 at 19:44:28, William Penn wrote:
>
>>The more hash I allocate, the slower the kN/s speed. Thus 4MB (the minimum) is
>>the fastest in my tests, typically about 450kN/s. If I increase that to say
>>256MB hash, the speed slows down to about 400kN/s. The more I increase hash, the
>>slower the kN/s speed.
>
>Correct observation, reasons:
>
>1) more HT lookup's and updates.

Sorry Ed, I don't see how you get more lookups. ( Updates took me a few minutes
)


>
>2) Spoiling the processor's DATA cache.

This is the biggest loss imo

Tony

>
>Ed
>
>
>>The kN/s speed peaks, then eventually starts to decrease. How long this takes
>>depends on the amount of hash. However in my tests, the long term speed
>>advantage of bigger hash never catches up with the long term speed obtained with
>>smaller hash. Thus I don't see any advantage whatsoever to using a hash table!
>>The opposite seems to be true!?
>>
>>I'm using the Shredder7 GUI, Shredder 7.04 UCI engine, AMD XP Athlon 2400+/640MB
>>RAM (608MB available). The GUI says the maximum I can allocate to hash is about
>>455MB, so I'm not near the limit. Of course I'm using fairly common practical
>>positions for these tests in Infinite Analysis mode, and the above indicated
>>results are typical.
>>
>>I get very similar results running Shreddermarks with different size hash. The
>>more hash, the lower the Shreddermark and corresponding kN/s.
>>
>>Now, will someone please refute this, or explain what I'm missing or
>>overlooking? Thanks!
>>WP



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