If it floating point division or integer?
Si
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I had the same question.
This is an email responce from other questions I had asked John.
This is from the creator of the code:
John Tromp
to me
More options Mar 9
hi Daniel,
> From your site: "By default, it uses a 64Mb transposition table with the
> twobig replacement strategy. Positions are represented as 64-bit
> bitboards, and the hash function is computed using a single 64-bit
> modulo operation, giving 64-bit machines a slight edge. The alpha-beta
> it runs twice as fast on my machine with 64 bit code vs 32 bit code.
The word "slight" above can be a bit of an understatement.
Apparently, trying to do 64 bit operations 32-bit at a time
incurs a lot more overhead than the simple factor of 2 suggests.
This is particularly true for 64 bit division, which requires many
32 bit operations to implement. Another contributing factor is
that activating the 64-bit extensions also gives you access to
a bigger register set.
> The 64 bit version is way faster. I was amazed. Using the same compiler
> options and machines with other benchmarks and applications and such, i
> usually only see a 5-14% increase in speed.
> I would like to understand why your benchmark is so much faster on the
> 64 bit than in 32 bit mode.
maybe Fhourstones is pretty unique in using 64 bit modulo operations...
And i had no idea what a modulo operation was until I decided to look it up:
[a href=\"http://en.wikipedia.org/wiki/Modular_arithmetic]http://en.wikipedia.org/wiki/Modular_arithmetic[/url]
So it is using Floating point.
Its also very interesting as to how slow this app is on my 1.25 GHz Mini Mac.
-Daniel
