Author: Robert Hyatt
Date: 12:58:46 06/20/02
Go up one level in this thread
On June 20, 2002 at 13:59:53, Tom Kerrigan wrote: >On June 20, 2002 at 11:46:21, Robert Hyatt wrote: > >>You are saying "64 bits won't help 99% of the applications and so they are >>really no faster." I am saying "64 bits definitely helps Crafty which means >>for chess there _is_ a potential benefit for them." > >I said nothing of the sort and you have yet to indicate that 64 bits helps >Crafty. You named two examples of 64-bit chips that run Crafty fast. I can name >more examples of 64-bit chips that run Crafty slow. So that must mean that >64-bit chips hurt Crafty, except in some corner cases, right? > >Here we have a situation where an indicator (Crafty's performance) changes when >you change two variables (datapath width and THE ENTIRE REST OF THE CHIP). >Anybody who was paying attention during 6th grade science class could tell you >that you can't draw conclusions from this data, but apparently this is not a >prerequisite for computer "science" professors in Alabama. > >-Tom Apparently "logic" isn't a strong point where you live either? Crafty _heavily_ depends on 64 bit operations. In Make/Unmake, in generating moves, in the evaluation, in the attack detection. In way over 80% of the code in fact. Only a few parts don't use bitboards (search to name one). Isn't it pretty intuitive that if 64 bit operations take two operations to complete, things are going to be significantly slower than if they take one? Did you remember the discussion here a few years back when Bruce and I took our NPS on P6/200 machines, and then on equal alphas, that my program scaled much better than his because of the 64 bit operations helping me while he had none in his program. Isn't it pretty obvious that something good happens when a 1ghz 64 bit machine produces performance that is faster than a 2ghz 32 bit machine? It is to me...
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