On Jun 6, 2011, at 11:22 PM, Hideki Kato wrote: > By my experiments on multithread shared tree parallelism, adding one > thread loses about 10 Elo (compared to single thread with the same > playout for a move). Maybe because, a newly starting thread cannot use > the results of the threads between (ie, the results of already running N > minus 1 threads; where N is the number of threads). So, even on SMP > systems, the performance scales in logarithmic but the loss linearly > scales in Elo. Getting correct number needs more experiments, though.
The math escapes me here. I think doubling the playouts gains in the neighborhood of 70 ELO points. If adding a thread costs 10 ELO, adding more threads would stop being beneficial after about 14 threads. Doubling from 7 to 14 would lose 7*10 ELO, equaling the gain of the extra playouts. After that, adding threads should actually lose ELO. Yet we see people trying to put together systems with 100s of CPUs. What am I missing? Mark _______________________________________________ Computer-go mailing list [email protected] http://dvandva.org/cgi-bin/mailman/listinfo/computer-go
