[mpich-discuss] determinism in collectives

Nichols A. Romero naromero at alcf.anl.gov
Mon Nov 12 21:00:20 CST 2012


I apologize if this has been asked a trillion times, if its documented somewhere just point it out to me online.

Are collective operations, such as sums, using MPI_Reduce deterministic? In other words, if I run MPI_Reduce N times on P tasks, will the sums always occur in the same order. Thus it would be reproducible to the expected precision.

Nichols A. Romero, Ph.D.
Argonne Leadership Computing Facility
Argonne National Laboratory
Building 240 Room 2-127
9700 South Cass Avenue
Argonne, IL 60490
(630) 252-3441

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