MPI Run Time System on SGI

• • On SGI, all MPI programs are launched with the mpirun command
    • mpirun -np N executable-name arguments syntax on a single host
    • multi-host execution of different executables is possible
  • The mpirun establishes connection with the Array Daemon with the socket interface.
  • The Array Daemon launches the mpi executable.
  • N+1 threads are started. One additional thread is the “lazy” thread which is blocked in mpi_init() call and terminates when all other threads call mpi_finalize()
  • The mpirun -cpr (or -miser) will work on the single host to avoid the socket interface to the Array Daemon (for Checkpoint/Restart facility)

• Note: start MPI programs with N < #procs

mpirun -np N t.exe

mpirun Host_A -np N a.out : Host_B -np M b.out

Program name, path,

environement variables

HiPPI optimized

communication

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