System operation

Batch (Serial) Operation

• prepare compiled executable; insert name and path into batch-run script as value of variable "myjob"
• submit batch-run script via "qsub"; each CPU does its own part of the work ONE AT A TIME
• monitor process via "qstat" until complete
• output and error sent to separate files in working directory

Parallel Operation

• prepare compiled executable; insert name and path into parallel-run script as value of variable "myjob"
• submit parallel-run script via "qsub"; all CPUs do their work SIMULTANEOUSLY
• monitor process via "qstat" until complete
• output and error sent to separate files in working directory

Example in Parallel Operation

We wish to calculate the numerical constant pi using the C code file cpi2.c...

• compile cpi2.c with "mpicc" ==> creates executable a.out
• create data file input.dat with number representing desired accuracy (rectangle rule)
• find "myjob=" in parallel-run script mpi_run.sh; append "a.out" to end of line
• remove prior output and error files
• submit mpi_run.sh via "qsub"
• monitor process via "qstat" until complete
• output and error sent to MPI-stdo.output and MPI-stderr.output respectively
• contents of MPI-stdo.output: "pi is approximately 3.1416009869231249, Error is 0.0000083333333318"