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Subject: Re: [hwloc-users] Understanding hwloc-ps output
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2012-05-30 09:54:24

Hello Youri,
When using openmpi 1.4.4 with --np 2 --bind-to-core --bycore" it reports
the following:
> [hostname:03339] [[17125,0],0] odls:default:fork binding child
> [[17125,1],0] to cpus 0001
> [hostname:03339] [[17125,0],0] odls:default:fork binding child
> [[17125,1],1] to cpus 0002

Bitmask 0001 and 0002 mean CPUs with physical indexes 0 and 1 in OMPI
1.4. So that corresponds to the first core of each socket, and that
matches what hwloc-ps says. Try "hwloc-ps -c" should show the same bitmask.

However, I agree that these are not adjacent cores, but I don't know
enough of OMPI binding options to understand what it was supposed to do
in your case.