If you are using MEMORY CHANNEL[TM], ensure that each machine in the cluster that you intend to use has been initialised for user-level access. You can check this by searching for a process called imc_ mapper on each machine. For example,
# ps a | grep imc_mapper | grep -v grep PID TTY S TIME CMD 657 ttyp2 U 0:00.01 /usr/sbin/imc_mapper
If this process does not exist on any host that you intend to use as part of the cluster, you should execute the following command (as root) on each such host:
# /usr/sbin/imc_init
This only needs to be executed once, and has effect until the machine is next shut down.
Compaq MPI uses shared memory for communication within a single host. The default system-wide maximum shared-memory segment a process can allocate is 4MB. For programs with a large number of processes this may need to be increased. This is done by editing the /etc/sysconfigtab file and adding (or modifying) the following entry:
ipc:
shm-max=size in bytes
For this change to take effect, a reboot is necessary.
If you specify a buffer size using the -ump_bufs option in the dmpirun command, then you must specify a buffer that is a multiple of 32.
Note: you are wasting memory resources if the size you specify is not a multiple of 8192.