Dear all, to explain the behavior of MPI_Reduce on our cluster i ran through the source of Open MPI 1.2.6. On line 357 i found a mistake (maybe ;-)). It should be:
return ompi_coll_tuned_reduce_intra_binary(sendbuf, recvbuf, count, datatype, op, root, comm, segsize); instead of return ompi_coll_tuned_reduce_intra_pipeline (sendbuf, recvbuf, count, datatype, op, root, comm, segsize); There are 2 indications: - the next branch is doing the same (32K pipelining) - the comment /* Binary_32K */ sounds not like "pipeline" ;-) Maybe someone is interested in. Regards, Andy -- Dresden University of Technology Center for Information Services and High Performance Computing (ZIH) D-01062 Dresden Germany Phone: (+49) 351/463-38783 Fax: (+49) 351/463-38245 e-mail: andy.geo...@zih.tu-dresden.de WWW: http://www.tu-dresden.de/zih
