Thanks! I used the second option and it worked just fine. Thanks for the help! Jeff On Tue, Oct 8, 2024 at 11:32 AM Zhou, Hui <[email protected]> wrote:

If you are using hydra – the default launcher installed with MPICH, the “-hosts” option accepts a comma separated list, so something like “-hosts node1:4,node2:4,node3:4”. The “:4” tells the launcher to assign 4 processes per host, so you don’t need another “-map-by” option. Alternatively, you could use “-hosts node1,node2,node3 -ppn 4” for the same effect.

-- Hui Zhou

*From: *Jeffrey Layton via discuss <[email protected]> *Date: *Tuesday, October 8, 2024 at 6:50 AM *To: *[email protected] <[email protected]> *Cc: *Jeffrey Layton <[email protected]> *Subject: *[mpich-discuss] How to use ppr with mpiexec?

Good morning, I'm trying to "port" an Open MPI script with MPICH and I'm having some trouble. I've got a few questions. What is the form of the "-hosts" option? Is it something like '-hosts node1: 4 node2: 4

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Good morning,

I'm trying to "port" an Open MPI script with MPICH and I'm having some trouble. I've got a few questions.

1. What is the form of the "-hosts" option? Is it something like '-hosts node1:4 node2:4 node3:4 ...'?

2. The Open MPI script has an option "-map-by ppr:4:node" that tells it to run 4 processes per node and then it runs as many nodes as needed to meet the number of processes. How can I do this in MPICH?

Thanks for the help!

Jeff