[Computer-go] Kas Cup - results and prizes

Michael Williams michaelwilliams75 at gmail.com
Sat Aug 11 20:34:17 PDT 2012

I wonder if spin-lock hurts hyperthreading.

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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