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Subject: Re: DB NPS (anyone know the position used)?

Author: Eugene Nalimov

Date: 21:34:01 01/26/00

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On January 26, 2000 at 23:53:49, Robert Hyatt wrote:

>On January 26, 2000 at 20:03:56, Peter W. Gillgasch wrote:
>
>>
>>This is what I think too. Even if they have still significant clock
>>cycle difference between "cheap" and "expensive" nodes they can overlap
>>the first FIND-AGGRESSOR / FIND-VICTIM operation with the slow eval
>>cycle. Anyone cares to post the actual cycle counts given in IEEE micro ?
>>
>>Anyway, I still believe that the argument regarding the fail low q nodes
>>is bogus because it assumes that the rate of fail low q nodes after a 10
>>ply full width search plus extensions and a 4 ply hardware search (is this
>>a q search only?)
>
>No.  This is a full-width search with extensions, + q-search.  It was
>basically the same idea as done in the belle machine, except collapsed to
>one chip.
>
>
>
>> multiplied with the clock cycle difference between the
>>slow and the fast eval can differ so greatly that it is not washed out
>>by the overhead move generation and tree traversal cycles which are
>>probably in the order of 1,1,2,2,2 = 8 cycles for each "cheap" cutoff.
>
>also remember that this is synchronous logic.  The fast eval can give a quick
>exit, but it still takes 10 cycles to exit as I understand it.  As he was very
>specific to say 24mhz processors searched 2.4 M nodes per second exactly.  And
>his 20mhz procssors searched 2M nodes per second exactly.  That tends to say
>that the fast eval/slow eval/other stuff are done in parallel and used as
>needed...  It would be harder to design a piece of hardware that had a variable
>number of cycles per node without microprogramming the thing...

I don't see why have a fast eval if it is evaluated in the same amount of
clocks. Why not use the "standard" one?

Eugene

>>
>>The whole proposition by Ernst implies implicitly that their on chip
>>move ordering is all messed up and their slow eval is painfully slow
>>compared with the move generation and tree traversal clock cycles.
>>
>>I donīt buy that.
>>
>>-- Peter
>>
>>>This would change if some of this stuff backs up into the software part of
>>>the search, of course...  But we seem to be talking only about the q-search
>>>as implemented in hardware, and every node saved is N nanoseconds saved, period.
>>
>>Bob I really hate it when we share the same opinion 8^)
>>
>>>(N is roughly 500, exactly 500 for the 20mhz processors, a little less for the
>>>24mhz processors).



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