Parallel Programming Guide for HP-UX Systems

MPI

Running

Chapter 2 45

However, this places processes 0 and 1 on hosta and processes 2 and 3 on hostb, resulting in interhost

communication between the ranks identiﬁed as having slow communication:

A more optimal appﬁle for this example would be

-h hosta -np 1 program1

-h hostb -np 1 program2

-h hosta -np 1 program1

-h hostb -np 1 program2

This places ranks 0 and 2 on hosta and ranks 1 and 3 on hostb. This placement allows intrahost

communication between ranks that are identiﬁed as communication hot spots. Intrahost communication

yields better performance than interhost communication.

Multipurpose daemon process HP MPI incorporates a multipurpose daemon process that

provides start–up, communication, and termination services. The daemon operation is

transparent. HP MPI sets up one daemon per host (or appﬁle entry) for communication. Refer

to “Communicating using daemons” on page 50 for daemon details.

hosta

process 0

process 1

hostb

process 2

process 3