Stockfish with 16 threads --- big news?

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zullil
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Stockfish with 16 threads --- big news?

Post by zullil » Sun Feb 15, 2015 11:46 am

Looks like a patch submitted by Joona has generated a 50 point ELO gain for Stockfish running 16 threads. So perhaps a big step forward in Stockfish's multi-threaded searching. Seems very promising.

http://tests.stockfishchess.org/tests/v ... 3e9fac133b

Lyudmil Tsvetkov
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Re: Stockfish with 16 threads --- big news?

Post by Lyudmil Tsvetkov » Sun Feb 15, 2015 11:53 am

zullil wrote:Looks like a patch submitted by Joona has generated a 50 point ELO gain for Stockfish running 16 threads. So perhaps a big step forward in Stockfish's multi-threaded searching. Seems very promising.

http://tests.stockfishchess.org/tests/v ... 3e9fac133b
Hope it will not pass, as otherwise I will not play your 16-core SF. :shock:

styx
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Re: Stockfish with 16 threads --- big news?

Post by styx » Sun Feb 15, 2015 12:02 pm

sounds very promising :D

Jouni
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Re: Stockfish with 16 threads --- big news?

Post by Jouni » Sun Feb 15, 2015 12:08 pm

Yes Komodo 9 with +20 ELO will be in very bad trouble. And there is already some +10 ELO patch after SF6 - unbelievable :shock: .
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lucasart
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Re: Stockfish with 16 threads --- big news?

Post by lucasart » Sun Feb 15, 2015 12:36 pm

zullil wrote:Looks like a patch submitted by Joona has generated a 50 point ELO gain for Stockfish running 16 threads. So perhaps a big step forward in Stockfish's multi-threaded searching. Seems very promising.

http://tests.stockfishchess.org/tests/v ... 3e9fac133b
Yes, this is huge!

Note that the test was auto-purged (chi-square test failed) twice.

Initially we had:
* bravone: 0 elo
* glinscott: +20 elo
* fastgm, bking: +50 elo

The chi-square test failed, and gave bravone as worst offender:
* glinscott: +20 elo
* fastgm, bking: +50 elo

And the chi-square test failed again, giving glinscott as worst offender. So we're left with:
* fastgm, bking: +50 elo

I don't know what's wrong with these machines. Could be OS or hardware. The only thing we know is the OS:
* bravone: Windows 2008 (old)
* glinscott: Linux 2.6.32 (old)
* fastgm: Linux 3.16 (recent)
* bking: Windows 8 (recent)

In other words the machines with modern OS saw a massive gain, while the others not so much (no gain on Windows 2008, and "only" 20 elo on an old Linux). But maybe the OS is a red herring, and it's about the hardware. I don't know. We can only speculate at this point.
Theory and practice sometimes clash. And when that happens, theory loses. Every single time.

styx
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Re: Stockfish with 16 threads --- big news?

Post by styx » Sun Feb 15, 2015 12:48 pm

is the smp patch a regression for one core? or am I reading the test results wrong

Michel
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Re: Stockfish with 16 threads --- big news?

Post by Michel » Sun Feb 15, 2015 12:54 pm

is the smp patch a regression for one core? or am I reading the test results wrong
That's extremely unlikely given that it is a non-functional change on one core. It's probably just an unlucky run.

EDIT: Actually checking again I see that the test wasn't even finished. Never draw conclusions from an unfinished test (statistics 101).
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Vinvin
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Re: Stockfish with 16 threads --- big news?

Post by Vinvin » Sun Feb 15, 2015 1:22 pm

styx wrote:is the smp patch a regression for one core? or am I reading the test results wrong
Yes, -1.8 after 32K games. That means -2% speed.
May be it's possible to reorganize "IF" conditions to not lose speed with nb threads = 1 :?

Joerg Oster
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Re: Stockfish with 16 threads --- big news?

Post by Joerg Oster » Sun Feb 15, 2015 1:24 pm

Michel wrote:
is the smp patch a regression for one core? or am I reading the test results wrong
That's extremely unlikely given that it is a non-functional change on one core. It's probably just an unlucky run.

EDIT: Actually checking again I see that the test wasn't even finished. Never draw conclusions from an unfinished test (statistics 101).
Though it is a non-functional change on one core, I experience a small slowdown on my box.
But I guess even a small elo-loss on one core of 1 or 2 elo would be acceptable, given the huge gain for 16 cores. 8-)
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Dr.Wael Deeb
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Re: Stockfish with 16 threads --- big news?

Post by Dr.Wael Deeb » Sun Feb 15, 2015 1:46 pm

Lyudmil Tsvetkov wrote:
zullil wrote:Looks like a patch submitted by Joona has generated a 50 point ELO gain for Stockfish running 16 threads. So perhaps a big step forward in Stockfish's multi-threaded searching. Seems very promising.

http://tests.stockfishchess.org/tests/v ... 3e9fac133b
Hope it will not pass, as otherwise I will not play your 16-core SF. :shock:
:shock:


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