On Tue, 19 Sep 2017 09:27:55 -0600 Faraz Hussain <i...@feacluster.com> wrote:
> I have never understood what these acronyms are. I've been involved > with HPC on the applications side for many years and hear these > terms pop up now and then. I've read through the wikipedia pages but > still do not understand what they mean. Can someone give a very high > level overview of what they are and how they relate to HPC? rdma: remote direct memory access, a way to move data from one node to another. Supported by for example Infiniband. ofed: a software distribution of network drivers, libraries, utilities typically used by users/applications to run on Infiniband (and other networks supported by ofed). In short: infiniband drivers verbs: one of many protocols supported on Infiniband providing "native performance". For example an MPI library can use verbs to efficiently transmit data over infiniband. Other protocols supported by Infiniband these days include UCX, MXM, OFI, DAPL, rsockets, ... psm: low level protocol that runs specifically on Pathscale/Truescale class Infiniband hardware. On this hardware psm is vastly more efficient than for example verbs. On modern Omnipath/OPA psm2 is used in a similar fashion. > Specifically, how does it relate to a simple hello world mpi program > like this: > > http://mpitutorial.com/tutorials/mpi-hello-world/ On an Infiniband cluster, when using multiple nodes, the MPI library can use verbs or psm to send data efficiently over the network. Verbs and psm drivers may come from an installation of ofed on these nodes (or not if using the OS built in Infiniband support). Different MPI implementations (such as OpenMPI, IntelMPI, MVAPICH2 etc.) makes different choices as to which protocols to use depending on many things (including available headers at compile time etc.). Cheers, Peter _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
