Re: Avoiding localhost as rank 0 with openmpi-default-hostfile

[Saurabh T]

I asked this before but did not receive a reply. Now with openmpi 5, I tried doing this with prte-default-hostfile and rmaps_default_mapping_policy = node:OVERSUBSCRIBE but I still get the same behavior: openmpi always wants rank 0 to be localhost. Is there a way to override this and set ranks by machine order in hostfile? Thanks.

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From: Saurabh T
Sent: Monday, November 6, 2023 10:44 AM
To: Openmpi <us...@lists.open-mpi.org>
Subject: Avoiding localhost as rank 0 with openmpi-default-hostfile

 

My openmpi-default-hostfile has

host1 slots=4

host2 slots=4

host0 slots=4

and my openmpi-mca-params.conf has

rmaps_base_mapping_policy = node

rmaps_base_oversubscribe = 1

If I invoke orterun -np 3 on host0, it puts rank0 on host0, rank1 on host1, rank2 on host2. I want it to put rank0 on host1, rank1 on host2, rank2 on host0 (as specified in the host file). I cannot use nolocal because I do want it to run on host0.

How can localhost being rank0 be avoided without using -H?

Thanks,

saurabh