[Computer-go] Kas Cup - results and prizes

Hideki Kato hideki_katoh at ybb.ne.jp
Sat Aug 11 20:45:38 PDT 2012


Michael Williams: <CAB0EdYWgs=gJsNT9rmkj8-uTLg72NYXnaFvd-8iQ_PJJF_JySQ at mail.gmail.com>:
>I wonder if spin-lock hurts hyperthreading.

Why do you think so?  If a spin-lock accesses memory and waits, 
simply another thread runs.  That's all.

Hideki

>On Sat, Aug 11, 2012 at 7:22 PM, Hideki Kato <hideki_katoh at ybb.ne.jp> wrote:
>> Petr Baudis: <20120811145900.GV19484 at machine.or.cz>:
>>>On Sat, Aug 11, 2012 at 12:52:12AM -0700, David Fotland wrote:
>>>> Yes, root parallelization with some sharing.
>>>> http://www.personeel.unimaas.nl/G-Chaslot/papers/parallelMCTS.pdf said it
>>>> was good and I tried it and it works well.
>>>
>>>The paper is not so relevant now, since the standard method of most
>>>programs is lockless tree parallelization, which is not covered.
>>>The locking overhead is quite significant, I'd expect, as locking
>>>instructions can AFAIK take hundreds of cycles.
>>
>> With spin-lock or hardware test-and-set instructions, locking overhead
>> is very small.
>>
>>>That said, root parallelization overperforming sequential simulations
>>>is something I never managed to reproduce and that seems rather
>>>surprising to me. It might have something to do with the way priors
>>>are done in the tree or some other engine-specific factors.
>>
>> I believe IBM Power processor's architecture may caused the super-linear
>> acceralaton.
>>
>> Hideki
>> --
>> Hideki Kato <mailto:hideki_katoh at ybb.ne.jp>
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Hideki Kato <mailto:hideki_katoh at ybb.ne.jp>



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