Author: Robert Hyatt
Date: 20:53:49 01/26/00
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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... > >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 don´t 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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