Re: [Computer-go] GTX 1080 benchmark

[Gian-Carlo Pascutto]

On 15/12/2016 12:35, Hiroshi Yamashita wrote:
>   F32F128F256MNIST
> GTX 1080  0.48ms  1.45ms  2.38ms  17sec,  CUDA 8.0, cuDNN v5.0, Core i7
> 980X 3.3GHz 6core
> GTX 1080  0.87ms  1.79ms  2.65ms  19sec,  CUDA 8.0, cuDNN v5.1, Core i7
> 980X 3.3GHz 6core
> GTX 980   0.60ms  1.51ms  2.80ms  24sec,  CUDA 7.5, cuDNN v5.0, Xeon
> W3680   3.3GHz 6core

The speedup from the GTX980 -> GTX1080 is very bad, isn't it? The card
has almost 100% more theoretical FLOPS, and much of the increase is due
to clock-speed and more shaders (and less so due to uarch changes) so
the extra FLOPS should be observable at least for the big networks.

I think you are entirely limited by setup/CPU/driver/API overhead. The
Hirabot network is bigger, the author has a smaller GPU, and his CPU is
faster. This would reduce the relative CPU overhead.

I suspect these overheads are also very large in cuDNN with a mini-batch
size of 1. My OpenCL code does not use the Winograd optimization and is
generic, identical code for AMD and NVIDIA cards, yet the performance is
very similar to cuDNN v5.1. This seems to indicate GPU processing is not
the actual bottleneck.

-- 
GCP
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Re: [Computer-go] Go Tournament with hinteresting rules

[Darren Cook]

> I have been told that bots that are based on MC play better when they only 
> record the result of each roll out (W or L)
> rather than the margin of victory.
> 
> To me this is counter-intuitive.
> 
> Does anyone have an intelligible reason why it should be so?

The search then optimizes for the probability of winning, rather than
optimizing for the largest margin of victory.

Imagine two stock traders. Their goal is to beat the market over the
next 12 months, and they both choose 10 companies from the FTSE100.
Trader A randomly chooses 10 companies with dividends that are paying
over the average for the FTSE100. Trader B chooses the 10 companies with
the highest dividends. Intuitively trader B should have earned more by
the end of the year, but there is a good chance that at least one
company will go bankrupt, and another will cut its dividend. Maybe the
other 8 choices will do well enough to keep him ahead overall, but
chances are that trade A will come out ahead.

Games of go tend to be dominated by life and death battles. There may be
a way for black to kill white's group, and win big, but it is awfully
complicated and we don't have time for exhaustive search. If we can
still win by letting white's group live small, that is a much safer path.

There is also a pragmatic reason: it is just one bit of information to
pass up the tree, so very easy to make a single number for chance of
win. With margin of victory you end up with the problem of how to pass a
probability distribution up the tree, and then what to do with it at the
top.
(The presence of the life/death battles means the distribution tends to
have multiple peaks, not be nice and gaussian.)

Darren



-- 
Darren Cook, Software Researcher/Developer
My New Book: Practical Machine Learning with H2O:
  http://shop.oreilly.com/product/0636920053170.do
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Re: [Computer-go] Go Tournament with hinteresting rules

[Lucas, Simon M]

The intelligible reason is that focussing on the win or loss
means that the bot is focussing on what actually matters: winning
and not losing.  If the bot focuses on the margin of victory
the play can be skewed to aim for big wins that may not
happen while paying insufficient attention to small losses.

Simon Lucas



-Original Message-
From: Computer-go [mailto:computer-go-boun...@computer-go.org] On Behalf Of 
Charles Leedham-green
Sent: 08 December 2016 23:23
To: computer-go@computer-go.org
Subject: Re: [Computer-go] Go Tournament with hinteresting rules

I have been told that bots that are based on MC play better when they only 
record the result of each roll out (W or L) rather than the margin of victory.

To me this is counter-intuitive.

Does anyone have an intelligible reason why it should be so?

Charles

> On 8 Dec 2016, at 22:56, Erik van der Werf  wrote:
> 
> On Thu, Dec 8, 2016 at 10:58 PM, "Ingo Althöfer" <3-hirn-ver...@gmx.de> wrote:
>> Playing under such conditions might be a challenge for the bots
> 
> Why? Do you think the humans will collude?  ;-)
> 
> Erik.
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