Open MPI logo

Open MPI Development Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Development mailing list

Subject: Re: [OMPI devel] why does --rankfile need hostlist?
From: Eugene Loh (Eugene.Loh_at_[hidden])
Date: 2009-06-19 16:21:43


Ralph Castain wrote:
The two files have a slightly different format
Agreed.
and completely different meaning.
Somewhat agreed.  They're both related to mapping processes onto a cluster.
The hostfile specifies how many slots are on a node. The rankfile specifies a rank and what node/slot it is to be mapped onto.
Agreed.
Rankfiles can use relative node indexing and refer to nodes received from a resource manager - i.e., without any hostfile.
This is the main part I'm concerned about.  E.g.,

% cat rankfile
rank 0=node0 slot=0
rank 1=node1 slot=0
% mpirun -np 2 -rf rankfile ./a.out
--------------------------------------------------------------------------
Rankfile claimed host node1 that was not allocated or oversubscribed it's slots:

--------------------------------------------------------------------------
[node0:14611] [[61560,0],0] ORTE_ERROR_LOG: Bad parameter in file rmaps_rank_file.c at line 107
[node0:14611] [[61560,0],0] ORTE_ERROR_LOG: Bad parameter in file base/rmaps_base_map_job.c at line 86
[node0:14611] [[61560,0],0] ORTE_ERROR_LOG: Bad parameter in file base/plm_base_launch_support.c at line 86
[node0:14611] [[61560,0],0] ORTE_ERROR_LOG: Bad parameter in file plm_rsh_module.c at line 1016
% mpirun -np 2 -host node0,node1 -rf rankfile ./a.out
0 on node0
1 on node1
done

It seems to me that the rankfile has sufficient information to express what I want it to do.  But mpirun won't accept this.  To fix this, I have to, e.g., supply/maintain/specify redundant information in a hostfile or host list.
So the files are intentionally quite different. Trying to combine them would be rather ugly.
Right.  And my issue is that I'm forced to use both when I only want rankfile functionality.
On Thu, Jun 18, 2009 at 1:52 PM, Eugene Loh <Eugene.Loh@sun.com> wrote:
In order to use "mpirun --rankfile", I also need to specify hosts/hostlist.  But that information is redundant with what I provide in the rankfile.  So, from a user's point of view, this strikes me as broken.  Yes?  Should I file a ticket, or am I missing something here about this functionality?