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Open MPI: Binding to core by default

After years of discussion, the upcoming release of Open MPI 1.7.4 will change how processes are laid out (“mapped”) and bound by default.  Here’s the specifics:

  • If the number of processes is <= 2, processes will be mapped by core
  • If the number of processes is > 2, processes will be mapped by socket
  • Processes will be bound to core
  • MPI_COMM_WORLD ranks will be assigned by slot

These are all the default values — they, of course, can be changed by the user via mpirun CLI options, environment variables, etc.

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At SC’13 next week? Come say hi!

sc13-logo_0Are you going to be in Denver at SC’13 next week?

Good!

You need to stop by the Cisco booth (#2535) and say hi to your friendly neighborhood Open MPI developers: Dave Goodell, Reese Faucette, and Jeff Squyres.

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Lawrence Berkeley Labs talk: Cisco Userspace NIC (usNIC)

Here’s the slides from my second talk, which is a deep technical dive into both how the usNIC technology works, and how we use that technology in the BTL plugin that we wrote for Open MPI (which is upstream starting with Open MPI v1.7.3).

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Lawrence Berkeley Labs talk: (Open) MPI, Parallel Computing, Life, the Universe, and Everything

Many thanks to the crew at LBL for hosting my talks yesterday.  There were many insightful questions and comments throughout both talks.

Here’s the slides from my first talk, entitled “(Open) MPI, Parallel Computing, Life, the Universe, and Everything.”  This is a general MPI/Open MPI talk, where I discussed the current state of Open MPI, and then talked in detail about two of Open MPI’s newest features: the MPI-3 “MPI_T” tools interface, and Open MPI’s flexible process affinity system.

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My new favorite Open MPI mpirun feature: tab completion

Today’s guest author is Nathan Hjelm, a Scientist 2 at Los Alamos National Laboratory.

We recently added scripts to support tab completion of mpirun flags and run-time MCA configuration variables to the Open MPI trunk development. The scripts support both bash and zsh and have a number of useful features (depending on the shell).

Can’t remember how to spell that MCA parameter name? Just hit <TAB>.
Can’t remember which transports are available? Just hit <TAB>.
Can’t remember the name of that mpirun CLI option? Just hit <TAB>.

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