Mpi

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Short message latency and NUMA effects

I’ve previously written a bunch about the effects of location, Location, LOCATION! on MPI applications. Here’s another subtle NUMA effect that a well-tuned MPI implementation can hide from you: intelligently distributing traffic between multiple network interfaces. Yeah, yeah, most MPI implementations have had so-called “multi-rail” support for a long time (i.e., using multiple network interfaces […]

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Open MPI and the MPI-3 MPI_T interface

Open MPI recently revamped its entire run-time parameter system (a.k.a., “MCA parameter system”) as part of its implementation effort for the “MPI_T” interface from MPI-3. The MPI_T interface is a standardized interface designed for MPI tools, but can be used by regular MPI application programs, too. Specifically, MPI_T provides programatic access to two types of […]

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Why MPI is Good for You (part 3)

I’ve previously posted on “Why MPI is Good for You” (blog tag: why-mpi-is-good-for-you).  The short version is that it hides the typical application programmer from lots and lots of underlying network stuff; stuff that they really, really don’t want to be involved in. Here’s another case study… Cisco’s upcoming ultra-low latency MPI transport is implemented […]