Re: [BProc] java libraries, LAM executables

[Brian B. <brb...@la...>]

On Thursday, July 24, 2003, at 03:46 PM, Gregory Shakhnarovich wrote:

> 2) When I try to run LAM/mpirun, it only manages to run executables 
> which
> are available on the nodes. So, since in our configuration my home
> directory is not mounted on the nodes (they are of course mounted on 
> the
> head node). , I have to move the executable somewhere to make it
> accessible to mpirun.

<snip>

> Is there a solution to this, without mounting the home directories on 
> the
> nodes?

I can't add much useful about your Java problem, but I can comment on 
your problems with LAM :).

LAM/MPI does automatically grab binaries from the head node to the 
client nodes.  This is one of the current restrictions in the LAM port 
to the BProc environment, and will probably be a restriction for at 
least the life span of the 7.0 release series.  It is possible to have 
LAM push the binaries out to the LAM session directory and have them 
execute there (note that this is very different than the BProc binary 
push).  This can be accomplished using the -s option to mpirun:

   mpirun -s n0 <app>

This functionality uses UDP point-to-point communication and does not 
scale particularly well.  However, it will work and may be the only 
viable option you have to mounting a common filesystem on your cluster.

Last I looked at the BProc interface, it was going to be difficult to 
implement the automatic migration of user binaries out to the compute 
nodes.  For various reasons, the processes started on the nodes must be 
started by the LAM daemon on that node.  Unless the situation has 
improved, this means forking the LAM daemon, migrating to the head 
node, execing, and migrating back to wherever I cam from.  This was a 
bit too much to chew off for the first stable release of LAM's BProc 
support :).  It is possible that there is a better way to do this - I'd 
be happy to hear any advice from the BProc experts out there....

Hope this helps,

Brian

-- 
   Brian Barrett
   LAM/MPI developer and all around nice guy
   Have a LAM/MPI day: http://www.lam-mpi.org/