[Computer-go] Kas Cup - results and prizes

Hideki Kato hideki_katoh at ybb.ne.jp
Sat Aug 11 21:49:08 PDT 2012


Michael Williams: <CAB0EdYXgbi9-+Su8DH1TrFeGR6kW4yku7pLhGbvzyi-yJwwXLA at mail.gmail.com>:
>Because two hyperthreads some of the same hardware.  And some of that
>hardware is required to do the spinning.  Just a thought.
>
>Found this with a quick search:
>http://archives.postgresql.org/pgsql-patches/2003-12/msg00345.php

I believe it's too old and cannot apply modern hyperthreading.

Hideki

>On Sat, Aug 11, 2012 at 8:45 PM, Hideki Kato <hideki_katoh at ybb.ne.jp> wrote:
>> 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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-- 
Hideki Kato <mailto:hideki_katoh at ybb.ne.jp>



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