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Subject: Re: Crap statement refuted about parallel speedup

Author: Vincent Diepeveen

Date: 17:34:35 09/21/01

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On September 18, 2001 at 23:30:51, Dave Gomboc wrote:

I already knew there are better move orderings possible because
i only get 0.85-0.90 cutoff rate versus most getting 0.90, however
static move ordering code is hell harder to write than simply
splitting in parallel and hoping it gives a quicker cutoff.

The 0.92 from crafty is not entirely true , because we should not
forget that its fliprate is 0.05 versus mine is under 0.01

So the qsearch can improve bigtime from crafty, because basically
that causes this bad fliprate!

That all our move orderings can be improved was already known
and some years ago i posted bigtime about this subject but the same
Bob wrote here:

  "our move ordering is that optimal that we cannot improve it anymore".

completely contradicting with what is getting said now!

>On September 18, 2001 at 18:27:01, Robert Hyatt wrote:

>>Before you label a statement as ridiculous, find me _one_ person that will
>>side with you and say that "yes, it is possible to get a > 2 speedup using
>>only two cpus on anything but anomaly positions.  Find _one_ person that will
>>agree...
>
>This is (okay, not very!) amusing... the statement is the exact opposite of
>reality, which (as Bob already knows) is that "it is only possible to get a < 2
>speedup using only two cpus on anything but anomaly positions".
>
>If a parallel algorithm consistently outperformed a sequential algorithm, then
>you've just discovered a better sequential algorithm as well (use time-slicing).
> If you then don't use this better sequential algorithm to compare your parallel
>algorithm against, you'd be comparing a good parallel algorithm against a shitty
>sequential algorithm, which would make the speedup result worthless.
>
>It is absolutely key that when people compare their parallel algorithm to their
>sequential algorithm that they compare the best possible sequential algorithm.
>There are more than a few papers that don't do this... thankfully, at least some
>of them have been rejected.
>
>Dave



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