Configuring Parallel Environments With QMON mentions that using sge_execd and sge_shepherd to create parallel tasks offers benefits over parallel environments that create their own parallel tasks. The UNIX operating system allows reliable resource control only for the creator of a process hierarchy. Features such as correct accounting, resource limits, and process control for parallel applications, can be enforced only by the creator of all parallel tasks.
Most parallel environments do not implement these features. Therefore parallel environments do not provide a sufficient interface for the integration with a resource management system like the grid engine system. To overcome this problem, the grid engine system provides an advanced parallel environment interface for tight integration with parallel environments. This parallel environment interface transfers the responsibility for creating tasks from the parallel environment to the grid engine software.
The distribution of the grid engine system contains two examples of such a tight integration, one for the PVM public domain version, and one for the MPICH MPI implementation from Argonne National Laboratories. The examples are contained in the directories sge-root/pvm and sge-root/mpi, respectively. The directories also contain README files that describe the usage and any current restrictions. Refer to those README files for more details.
For the purpose of comparison, the sge-root/mpi/sunhpc/loose-integration directory contains a loose integration sample with Sun HPC ClusterToolsTM software, and the sge-root/mpi directory contain a loosely integrated variant of the interfaces for comparison.
The performance of a tight integration with a parallel environment is an advanced task that can require expert knowledge of the parallel environment and the grid engine system parallel environment interface. You might want to contact your Sun support representative distributor for assistance.