Back to this problem. The last suggestion was to upgrade to 1.3.3, which has been done. Still cannot get this code to run in 64 bit mode with torque. What I can do is run the job in l6 bit mode using a hostfile. Specifically, if I use qsub -I -l nodes=2:ppn=1 torque allocates two nodes to the job, and since this is an interactive shell, logs me in to the controlling node. In this example process rank 0 is n72 and process rank 1 is n89: [sims@n72 4000]$ mpirun --display-allocation -pernode --display-map hostname
====================== ALLOCATED NODES ====================== Data for node: Name: n72.clust.nist.gov Num slots: 1 Max slots: 0 Data for node: Name: n89 Num slots: 1 Max slots: 0 ================================================================= ======================== JOB MAP ======================== Data for node: Name: n72.clust.nist.gov Num procs: 1 Process OMPI jobid: [47657,1] Process rank: 0 Data for node: Name: n89 Num procs: 1 Process OMPI jobid: [47657,1] Process rank: 1 ============================================================= n89 n72.clust.nist.gov My hostfile is [sims@n72 4000]$ cat hostfile n72 n89 If, logged in to n72, I use the command mpirun -np 2 ./MPI_li_64 the job fails with a mpirun noticed that process rank 1 with PID 10538 on node n89 exited on signal 11 (Segmentation fault). If I use the command mpirun -np 2 --hostfile hostfile ./MPI_li_64 the same thing happens. However, if I ssh to n73, for example, and use the command mpirun -np 2 --hostfile hostfile ./MPI_li_64 everything works fine. So it appears that the problem is with torque. Any ideas?