[Pachi] Hardware, configuration, and donations

Petr Baudis pasky at ucw.cz
Thu Aug 25 15:14:07 CEST 2011


On Thu, Aug 25, 2011 at 11:43:23AM +0100, Gareth Davies wrote:
> I've been looking through the documentation but am having a hard time figuring out what aspects of hardware are most important to pachi's (I assume uct) playing strength.  For example, suppose pachi is running on a dual core 1.6 GHz 32-bit system and has 1 GB or RAM to play with.  If I could choose to upgrade one of the following four aspects of my hardware which would improve pachi the most?
> quad core
> 3.2 GHz
> 64-bit
> 2 GB RAM

  Adding cores is by far the best. If you double the number of cores,
Pachi (run with threads=4) will either play twice as fast with the same
strength, or perform twice as many simulations (which is, extremely
roughly, equivalent to one stone strength boost).

  Frequency is tricky. It is a processor-specific metric and usually
it makes sense to compare it only between processors within the same
product line.

  64-bit is probably improvement, but I'm not sure we have ever
quantified it and how large improvement it is. You will need more memory
if you switch to 64-bit.

  RAM matters iff you are running out of it - you see "memory limit
hit" messages in Pachi's output, it means the tree will not fit into
available memory anymore and the search terminates sooner than it could.
On 8-threaded i7-920, around 4GiB RAM usually suffices for ~30s/move
time settings.

> I'm considering renting some computing power for pachi (My own server uses a single Intel Atom processor).  Anything you could recommend?  If you have ideal processing power at your disposal then I'd love to rent some of that using the distributed module (my budget is limited as I'm a student but I might be able to go up to 60 GBP per month).

  I think both of us have just computing power we cannot rent further,
but maybe someone else on the list could. If you gain some experience
with running Pachi e.g. on Amazon EC2, we'll be delighted to hear about
it.  But I have no idea if it is the most economic solution.

> My configuration question is simple.  If I pit pachi against itself, on the same hardware, one using the joseki dictionary and the other not, which would be more likely to win?  Would the answer depend on the hardware?

  The influence of the joseki dictionary itself on computer-computer
play is extremely tiny, so you would need many thousands of games to
see anything. We use that one particular feature just to make Pachi play

> Finally donations.  Is it possible to donate Bitcoins?  http://bitcoin.org/.  If you haven't heard of it or have a policy against it then don't worry; it's just my preferred way of sending donations so I thought I'd ask.  I'm usually happy to donate more and more frequently with a Bitcoin option because it's so easy to do but VISA will be fine if preferred.

  It is certainly possible! The address is


				Petr "Pasky" Baudis
UNIX is user friendly, it's just picky about who its friends are.

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