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Subject: [OMPI users] bind-to-socket across sockets with different core counts
From: Noah Knowles (nknowles_at_[hidden])
Date: 2013-08-22 17:48:18


Hi, newb here, so sorry if this is a dumb question but I haven't found
an answer. I am running OpenMPI 1.7.2 on a small Rocks 6.1, Bladecenter
H cluster. I am using the bind-to-socket option on nodes with different
numbers of cores per socket. For the sample output below, compute-0-2
has two 6-core sockets and compute-0-3 has two 8-core sockets.

[1,4]<stderr>:[compute-0-2.local:03268] MCW rank 4 bound to socket
0[core 0[hwt 0]], socket 0[core 1[hwt 0]], socket 0[core 2[hwt 0]],
socket 0[core 3[hwt 0]], socket 0[core 4[hwt 0]], socket 0[core 5[hwt
0]]: [B/B/B/B/B/B][./././././.]
[1,5]<stderr>:[compute-0-2.local:03268] MCW rank 5 bound to socket
1[core 6[hwt 0]], socket 1[core 7[hwt 0]], socket 1[core 8[hwt 0]],
socket 1[core 9[hwt 0]], socket 1[core 10[hwt 0]], socket 1[core 11[hwt
0]]: [./././././.][B/B/B/B/B/B]
[1,6]<stderr>:[compute-0-3.local:03816] MCW rank 6 bound to socket
0[core 0[hwt 0]], socket 0[core 1[hwt 0]], socket 0[core 2[hwt 0]],
socket 0[core 3[hwt 0]], socket 0[core 4[hwt 0]], socket 0[core 5[hwt
0]]: [B/B/B/B/B/B/./.][./././././././.]
[1,7]<stderr>:[compute-0-3.local:03816] MCW rank 7 bound to socket
0[core 6[hwt 0]], socket 0[core 7[hwt 0]], socket 1[core 8[hwt 0]],
socket 1[core 9[hwt 0]], socket 1[core 10[hwt 0]], socket 1[core 11[hwt
0]]: [././././././B/B][B/B/B/B/./././.]

Is this behavior intended? Is there any way to cause bind-to-socket to
use all cores on a socket for the 6-core AND the 8-core nodes? Or at
least to have that last binding not spread across cores on two sockets?
I've tried a rankfile too, but had errors-- that should probably be a
separate thread though.

Thanks,
Noah