Author: Vincent Diepeveen
Date: 07:20:53 09/05/02
Go up one level in this thread
On September 04, 2002 at 18:38:17, Dann Corbit wrote:
My posting was with regard to the DTS article.
The crafty matter is something different. I say crafty
is not prepared for the future there, because it relies too
much upon 4 things for its speedup SMP
- memory/communication speed
- random splitting instead of chosen like in DTS
- asymmetric king safety (hard penalties for the own king side
are very good for the speedup), which is good for speedup and
bad for play, not used by majority of programs in program-program.
The existance of this feature is the ultimate proof on how bad
Crafty's king safety is.
- that crafty would for having n processors a speedup of
1 + 0.7(n-1)
Bob doesn't show a 1.7 speedup at all. He shows 1 position where
every algorithm as historic has been proven (bk22) gets a good speedup.
The last point is very serious.
GCP ran 30 positions at bob's quad xeon and had an average speedup of 2.8
at it with crafty.
That is not near 3.1 which is claimed according to the formula,
and it is measured very accurately over many positions.
Bob also received the outputs of it. and still has them.
>My take on the matter (in one paragraph):
>Robert wrote a paper on parallel speedup, showing a 1.7 increase for 2 CPU's (as
>derived from his more general formula). Vincent was unable to reproduce this
>sort of speedup, and thought the research was faulty. Robert agreed that the
>test set was limited and you won't always get that sort of speedup, but as an
>average (over a broad set of positions) that's about what he got. There has
>been some acrimony over whether superlinear speedups are possible. I think that
>the jury is still out on that one.
>
>At any rate, that's my take on the whole thing.
>
>Vincent always sees things in pure, jet black or gleaming, powder white. If
>something isn't terrific, then it is pure junk. While I think his mode of
>interesting is a bit odd, it's one of the things that make Vincent interesting.
>
>Robert has always been a man of strong convictions, and if you call him a
>'noo-noo head' he'll call you one back. He isn't one to back down when he
>thinks he is right. That's one of the things I like about Dr. Hyatt.
>
>When these two styles happen to ram into one another, the sparks are sure. A
>philosophical question is often asked:
>"What happens when an immovable object meets an irresistable force?"
>
>The 'debate' is an answer to that question.
>;-)
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