On Fri, Jun 11, 2010 at 2:52 PM, Mark Boon <[email protected]> wrote:
> On Thu, Jun 10, 2010 at 11:09 PM, Erik van der Werf > <[email protected]> wrote: > > Lukasz Lew's libego used to have the fastest light playouts. IIRC some > > years ago it already got over 100k playouts per second for 9x9 on one > > core. I guess it should now be possible to get over 200k light > > playouts per second. Others on this list may have more accurate > > numbers. > > Cores didn't really get much faster recently, so what makes you think > it could be twice as fast now? > That's not true. Cores are clearly getting faster with each new processor, just not quite as quickly as before. I think now you have to wait about twice as long (or something like that) to get something that is twice as fast at running a single processor program. I think we will get at least a few more years of this (a few more doublings of raw single core speed.) Lukasz code is highly optimized for very fast playouts. But he does take some shortcuts to get this amazing speed - shortcuts that hurt the quality of each playout a bit. I don't think his code is appropriate for adapting to heavy playouts. Don > > A while ago I took a peek at his code, but I found it hard to > understand. In a logical sense I saw some places that seem sub-optimal > from an algorithmic point of view. But I figured the numbers speak for > themselves. At the time it was reported it did something like 40K > playouts per Ghz. But I didn't manage to verify this as I never got > his code to compile. It's probably a bit too Linux specific in its > setup. The main reason I didn't look into it further (apart from lack > of time) is that AFAIK it doesn't keep liberties. But I think it does > keep a few other useful things. > > People refer to 'light' playouts but may mean different things. I like > to at least make the distinction between playouts that keeps correct > liberty counts and playouts with pseudo liberties. In my personal > code, pseudo liberties is only marginally faster than real liberties > so I find it highly preferable to keep real liberties so it can be > used by a tactical module. But I didn't spend nearly as much time as > Lukasz trying to optimize it. > > The other thing that needs care when touting playout speeds is whether > this is purely measuring playouts, or playouts while building a MCTS > tree (or hashtable). > > My Java implementation of light playouts with liberties does something > like 30K-35K per second on one core. I think it's similar on a 2.6Ghz > i5 as on an older 2.8Ghz. The same code directly translated to C is > about twice as fast. > > Mark > _______________________________________________ > Computer-go mailing list > [email protected] > http://dvandva.org/cgi-bin/mailman/listinfo/computer-go >
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