LAM 6.1 Release Notes

The major enhancements in LAM 6.1 are:

client-to-client MPI communication that utilizes shared memory in conjunction with TCP/IP
an implementation of MPI-2 dynamic processes
improved UNIX standard I/O capability from all nodes

Multi-protocol Communication

MPI processes that reside on the same machine communicate via shared memory. MPI processes that reside on different machines communicate via TCP/IP. This is now the factory supplied behaviour of LAM/MPI "client-to-client" communication, enabled by the -c2c option of mpirun(1).

A basic shared memory communication path, based on System V IPC, is available for all supported machines. In addition, some machines offer faster alternatives for either the shared memory or the shared memory locks, or both.

Sun Solaris: Solaris semaphores
SGI IRIX: SGI shared arenas, SGI locks
HP HPUX: HPUX System V shared memory, HPUX user level locks

MPI-2 Dynamic Processes

LAM 6.1 includes an implementation of the dynamic processes chapter of the SC96 draft of the MPI-2 standard. Both parent/child spawning and client/server rendez-vous are supported. The capability is described in the MPI-2 document, the LAM 6.1 document and the LAM 6.1 manual pages.

It is possible to start singleton MPI applications from the shell (without mpirun(1)) and then start other processes via MPI_Spawn(2). PVM programs with a similar design should port easily to MPI.

LAM's dynamic node and fault tolerant features in conjunction with MPI dynamic processes make a good environment for developing load balancing and scheduling systems.

UNIX Standard I/O

LAM 6.1 enables all processes, local and remote, to write to standard output and error, with the data appearing on the terminal and node where mpirun(1) was invoked. This is accomplished via the scalable LAM daemon. Standard input is possible for local processes, who also have their current working directory set to match the mpirun(1) invocation. It is possible to redirect an application's standard I/O by using the shell redirects with mpirun(1).

LAM / MPI Parallel Computing / Ohio Supercomputer Center / lam@tbag.osc.edu