Okay, George - this is fixed in r21690.
Thanks again
Ralph
On Jul 15, 2009, at 2:40 PM, Ralph Castain wrote:
Ah - interesting scenario!
Definitely a "bug" in the code, then. What it looks like, though, is
that the jdata->num_procs is wrong. There shouldn't be any way that
the num_procs in the node array is different than jdata->num_procs.
My guess is that the rank_file mapper isn't correctly maintaining
the bookkeeping when we map the procs beyond those in the rankfile.
I'll dig into it - have to fix something for Lenny anyway.
Meantime, this change looks fine regardless as it (a) is better code
and (b) protects us against such errors.
Thanks for catching it!
Ralph
On Wed, Jul 15, 2009 at 2:30 PM, George Bosilca
<bosi...@eecs.utk.edu> wrote:
I think I found a better solution (in r21688). Here is what I was
trying to do.
I have a more or less homogeneous cluster. In fact all processors
are identical, except that some are quad core and some dual core. Of
course I care how my processes are mapped on the quad cores, but not
really on the dual cores.
My approach was to use the following configuration files.
In /home/bosilca/.openmpi/mca-params.conf I have:
orte_default_hostfile=/home/bosilca/.openmpi/machinefile
rmaps_rank_file_path = /home/bosilca/.openmpi/rankfile
rmaps_rank_file_priority = 100
In /home/bosilca/.openmpi/machinefile I have the full description of
the cluster. As an example:
node01 slots=4
node02 slots=4
node03 slots=2
node04 slots=2
And in the /home/bosilca/.openmpi/rankfile file I have:
rank 0=+n0 slot=0
rank 1=+n0 slot=1
rank 2=+n1 slot=0
rank 3=+n1 slot=1
As long as I spawn jobs with less than 4 processes everything worked
fine. But when I used more than 4 processes, orterun segfaulted.
After debugging I found that the nodes, lrank and nrank arrays were
allocated based on the jdata->num_procs, but then filled based on
the total number of processes in the jdata->nodes array. As it
appears that the jdata->num_procs is somehow modified based on the
number of entries in the rankfile, we end-up writing outside the
allocation and then segfault. Now with the latest patch, we can cope
with such a scenario by only packing the known information (and thus
not writing outside the allocated arrays).
This might not be the best approach, but it is doing what I'm
looking for ...
george.
On Jul 15, 2009, at 15:50 , Ralph Castain wrote:
The routed comm system relies on each daemon having complete
information as to where every process is located, so the expectation
was that only full maps would ever be sent. Thus, the nidmap code is
setup to always send a full map.
I don't know how to even generate a "partial" map. I assume you are
doing something offline? Is this to update changed info? If so,
you'll also have to do something to update the daemon's maps or the
comm system will break down.
Ralph
On Wed, Jul 15, 2009 at 1:40 PM, George Bosilca
<bosi...@eecs.utk.edu> wrote:
I have a question regarding the mapping. How can I declare a partial
mapping ? In fact I only care about how some of the processes are
mapped on some specific nodes. Right now if the rmaps doesn't
contain information about all nodes, we give up (before this patch
we segfaulted).
Does it means we always have to declare the whole mapping or it's
just that we overlooked this strange case?
george.
Begin forwarded message:
Author: bosilca
Date: 2009-07-15 15:36:53 EDT (Wed, 15 Jul 2009)
New Revision: 21686
URL: https://svn.open-mpi.org/trac/ompi/changeset/21686
Log:
Reorder the nidmap encoding function. Add a check to make sure we
don't write
outside the boundaries of the allocated array.
However, the problem is still there. If we have rmaps file
containing only
partial information the num_procs get set to the wrong value (the
number of
hosts in the rmaps file instead of the number of processes requested
on the
command line).
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