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Subject: Re: Crafty MPC ( Is it Hyper Threading?)

Author: Sune Fischer

Date: 03:37:26 09/14/03

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On September 13, 2003 at 20:09:09, Jeremiah Penery wrote:

>If you want to calculate the ratio of effective nodes/time, I'm not really sure
>how you plan to do it.  How do you define an effective node, first of all?  The
>serial search duplicates nodes often enough on its own that I don't see a way to
>calculate a difference between wasted serial nodes and wasted parallel nodes.
>Or am I just completely off-base here?

Wasted parallel nodes is wasted serial nodes *plus* parallel search overhead.

We can't do a lot about the wasted serial nodes, because we'll never have a 100%
perfect move ordering and pruning strategy, so let's not worry about how to
measure that (right now) :)

What's important is that we can look at the nps in a parallel search and
directly compare them to the nps in a serial search.

Take hyperthreading, Crafty apparently gets 30% higher nps so people who doesn't
know about parallel search overhead might think this means it will solve things
30% faster.

I would like this number corrected so that it showed how much faster we should
expect it to solve positions, probably only 10-15 percent faster, so the nps
should be 115% higher, and not 130%.

Afterall it's not about getting high nps, it's about getting maximum efficiency.

I'm not sure how hard it would be to implement though...

-S.



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