On Fri, Jan 30, 2009 at 10:28:29PM +0100, Håkon Bugge wrote: > Greg, we (and your former colleagues at PathScale) have exchanged > opinions on RDMA vs. Message Passing. Based on SPEC MPI2007, you will > find that an RDMA based DDR interconnect using Platform MPI performs > better than a Message Passing stack using DDR.
Well, like any experiment in this space, this isn't quite head-to-head. It could easily be the case that Platform MPI has some better collectives or other implemtation details which provide a performance boost outside of the RDMA vs. message passing issue. I thought you had a PSM implementation of Platform MPI? In which case, perhaps you could compare it against the QLogic MPI on the same hardware, to see what these other effects might be. It would also be interesting to compare Platform MPI against MVAPICH on the same hardware -- do you have those numbers? -- greg _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
