12 Nov
2012
12 Nov
'12
9:35 p.m.
The MPI standard does not guarantee this. For example, an implementation could use topology-aware reductions or an MPI_ANY_SOURCE while waiting for messages from peers making the order in which the reduction operations are applied different for each run. -- Pavan On 11/12/2012 09:00 PM US Central Time, Nichols A. Romero wrote:
Hi,
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.
-- Pavan Balaji http://www.mcs.anl.gov/~balaji