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Subject: Re: How well do today's "Deep" engines scale?

Author: Andreas Guettinger

Date: 14:05:50 07/19/05

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On July 19, 2005 at 16:34:57, Anson T J wrote:

>As all threads don't calculate the same, the NPS is a fair enough measurement.
>I'm more interested in the NPS than time to depth.

???

Like Joachim already mentioned, this makes absolutely no sense to measure the
speedup of dual vs single processor version in nps.
It's like to measure the ELO in nps. Or measure the weigth of a car in miles per
hour.

The speedup of single vs dual processor version is given by the implementation
of the multithreaded search method. In a worse case a lot of same nodes are
calculated by both threads, which results in a bad speedup. This however has no
effect on the NPS. It can be even the contrary. A "bad" multhithreaded search
implementation can have very little communication between the threads. This may
result in a high NPS rate of the "deep" version, despite of a very bad speedup,
compared to a very good multi processor search routine, which needs more code
for communication between the threads to ensure very little redundancy of the
search tree and therefore gives a good speedup.

So I beg you to reconsider the objection of Joachim.

regards
Andy



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