On Sun, 4 May 2003, Rohan Inamdar wrote:
> I am using MPI_Comm_spawn and i want to spawn a new process on a
> particular node in the cluster.
>
> I read about MPI_Info and it says it is "a set of key-value pairs
> telling the runtime system where and how to start the processes".
>
> Also I found that there is a reserved key 'host' for MPI_Info object.
> (Value is a hostname. The format of the hostname is determined by the
> implementation.)
Note that this key is only suggested by the MPI standard; it is not
mandated. The LAM 6.5 series only supports the "file" key, which can be
used to pass an appschema to MPI_Comm_spawn, which effectively allows you
to pass in any arguments that are valid to mpirun to MPI_Comm_spawn. See
the MPI_Comm_spawn(3), mpirun(1), and appschema(5) man pages.
In LAM 7.0, more keys are supported, but we still do not directly support
"host" (nor the other keys that you asked about in your followup post).
Note, however, that the appschema key is still available, and effectively
supports those keys.
The "file" key name has been deprecated (although it still works) and
renamed to "lam_spawn_file". "lam_spawn_sched_round_robin" allows you to
start scheduling new processes on a given node in a round robin fashion
(as opposed to implicitly starting with c0). See the man page in the
7.0b8 tarball for MPI_Comm_spawn(3) for more details (7.0b8 was just
released yesterday; see http://www.lam-mpi.org/beta/)
> My question is how can i specify hostname (if hostname is
> sparc7.cs.iit.edu)? Is my understanding of these descriptions correct?
In general, LAM avoids using hostnames once a universe has been booted.
Instead, the nX and cX nomenclatures are used to identify nodes instead
(e.g., the output of lamnodes).
--
{+} Jeff Squyres
{+} jsquyres_at_[hidden]
{+} http://www.lam-mpi.org/
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