Author: Dann Corbit
Date: 17:13:07 01/20/06
Go up one level in this thread
On January 20, 2006 at 19:36:00, Uri Blass wrote:
>On January 20, 2006 at 17:58:42, Dann Corbit wrote:
>
>>On January 20, 2006 at 17:27:10, Uri Blass wrote:
>>
>>>On January 20, 2006 at 17:07:09, Dann Corbit wrote:
>>>
>>>>Consider Deep Shredder or Deep Fritz on a 4 way box with dual core CPUs
>>>>8x CPU speed would mean 150 Elo (with some SMP loss).
>>>>
>>>>That is a system runnable today.
>>>>
>>>>Now, imagine an 8 way box with 4 cores each (probably next year)
>>>>That would be another 100 Elo.
>>>>
>>>>If we lost one whole doubling from SMP loss, it would still be +200 Elo.
>>>>
>>>>But I think that on a single CPU, Rybka is probably the strongest.
>>>
>>>I think that there is a diminishing returns so I am not sure if your estimate is
>>>correct.
>>
>>I allowed for a 50% SMP loss for the +200 Elo estimate.
>>I think that even with 32 cores, that should be achievable.
>>{16x speedup for 32 cores}
>>
>>But maybe not.
>>
>>I did see an experiment where linear speedup was achieved for a large number of
>>processors.
>>
>>In order to accomplish it, the tree was simply expanded and processors were
>>given leaf nodes of the expanded tree to work on.
>>
>>And so, with 20 CPUs at the root position, you would give each CPU one of the 20
>>possible first moves to work on. And if you had 400 CPUs, you could expand 2
>>levels.
>>
>>It is also what the chessbrain project does, according to my understanding.
>>Of course, they have a huge network latency to overcome, so it is not like SMP
>>at all. That is why I did not consider network based solutions for the
>>strongest possible chess engine.
>
>Note that I think about diminishing return from being twice faster and not only
>about diminishing returns from more processors.
Good point (I was referring to hardware speedup only). I do not think it has
been proven one way or another that the returns do diminish (though by
gedankenexperiment, they ought to). I have seen conflicting studies that say
they do and that they don't.
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