[mpich-devel] Suboptimal MPI_Allreduce() for intercommunicators

Lisandro Dalcin dalcinl at gmail.com
Thu May 1 03:54:38 CDT 2014

On 30 April 2014 18:56, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
> It was probably done that way to avoid the need for memory allocation, but can you add a ticket in Trac and we will look at it.


> (For example, on one side of the intercommunicator sendbuf=1 byte, recvbuf=1 gigabyte; on the other side, sendbuf=1 gigabyte, recvbuf=1 byte)

For Allreduce, you cannot have 1 byte/  1gigabyte at each side.

Lisandro Dalcin
Predio CONICET-Santa Fe
Colectora RN 168 Km 472, Paraje El Pozo
3000 Santa Fe, Argentina
Tel: +54-342-4511594 (ext 1016)
Tel/Fax: +54-342-4511169

More information about the devel mailing list