Darren Cook: <4b0c6706.7070...@dcook.org>: >> Also, on 19x19 board, current 16-core cluster version performs almost >> the same as 8-core shared memory pc such as Mac Pro, which Yamato used >> for KGS. > >Hi Hideki, >Is that difference due to a scaling limit of Zen, or is this due to the >cluster overhead? Would moving from gigabit to infiniband help, or is >the limit more to do with the lack of shared memory?
I'm right now evaluating the scaling (:-). The performance gap is perhaps due to the algorithms. Almost all cluster versions of current strong programs (MoGo, MFG, Fuego and Zen) use root parallel while shared memory computers allow us to use thread parallelism, which gives better performance. The main reason, I guess, is that the latter increses the depth of the search tree according to the number of processors (cores) while the former does not. One interesting observed thing of root parallel is that the scaling depends on the time for a move; longer time setting shows better scalability, when the time period to exchange root information is fixed. In other words, each time setting has its best number of nodes. This makes things complicated :(. The scaling limit of Zen is still unknown, though I expected that the playouts of Zen was not so random that it did not scale well, before starting this joint project with Yamato. >>T2K HPC cluster > >This seems to be a cluster specification rather than an actual machine. >Can you tell us more about how many cores you are experimenting with, >and how the programs scale? (Are all your experiments with Zen, or are >you trying to run other programs on a cluster too?) I'm running only Zen on the cluster, though I'd like to run my Fudo Go as well if I have (had?) time. Name: T2K Open Supercomputer (Todai) #Todai is an abbreviation of University of Tokyo in Japenese. Hardware: HITACHI HA8000-tc/RS425 Number of nodes: 952 Number of cores of each node: 16 #I can use up to 64 nodes; 1024 cores in total Processor: AMD Opteron 8356 (quad-core) 2.3 GHz Memory of each node: 32 GB Interconnect: Myricom Myri-10G Operating System: RedHat Enterprise Linux 5 #Flops numbers are omitted. :) http://www.cc.u-tokyo.ac.jp/service/ha8000/intro.html (in Japanese) T2K stands for Tokyo, Tsukuba and Kyoto (T, T, K). See http://www.open-supercomputer.org/ (in English) for the idea of T2K Open Supercomputer. Hideki -- g...@nue.ci.i.u-tokyo.ac.jp (Kato) _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
