I haven't implemented this successfully, so I probably shouldn't be giving advice to anyone, but what I was trying to do when we stopped developing dimwit was the following: * When a thread enters a node of the UCT tree, increment the number of losses (This will discourage other threads from entering the same branch). * When you want find out if the playout was actually a win or a loss, increment the wins counter and decrement the losses counter.
All the manipulations can be done without locks with a tiny little bit of assembly or with intrinsic functions. If you need details, I can try to get you sample code for Mac OS X or Linux (both on x86). Álvaro. On Mon, Apr 13, 2009 at 6:08 PM, Rémi Coulom <remi.cou...@univ-lille3.fr> wrote: > Michael Williams wrote: >> >> What tricks are people doing to minimize the performance degradation due >> to multiple threads contending for access to the tree (in MCTS)? Do you >> only lock a portion of the tree? How would that work? >> >> _______________________________________________ >> computer-go mailing list >> computer-go@computer-go.org >> http://www.computer-go.org/mailman/listinfo/computer-go/ > > If you are motivated, you can try a completely lockless solution: > http://computer-go.org/pipermail/computer-go/2008-March/014537.html > It scales well up to 16 cores: > http://computer-go.org/pipermail/computer-go/2008-March/014547.html > > Using a single global lock is really very inefficient, especially for 9x9 or > if you have many cores. > > Rémi > _______________________________________________ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/ > _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
