Editing Parallel Virtual Machine (section)

== Design ==

PVM is a software system that enables a collection of heterogeneous computers to be used as a coherent and flexible concurrent computational resource, or a "parallel [[virtual machine]]".

The individual computers may be shared-memory or local-memory [[multiprocessor]]s, [[Vector processor|vector]] [[supercomputer]]s, specialized [[CPU|graphics engines]], or [[Scalar processor|scalar]] [[workstation]]s and [[personal computer|PC]]s, that may be interconnected by a variety of [[computer network|network]]s, such as [[Ethernet]] or [[Fiber Distributed Data Interface|FDDI]].

PVM consists of a run-time environment and library for [[message passing]], task and resource management, and fault notification. While PVM will not automatically make a commercial software package run faster, it ''does'' provide a powerful set of functions for manually parallelizing an existing source program, or for writing new parallel/distributed programs.

The PVM software must be specifically installed on every machine that is to be used in a given "virtual machine". There is no "automatic" installation of [[executable]]s onto remote machines in PVM, although simply copying the <code>pvm3/lib</code> and <code>pvm3/bin</code> directories to another ''similar'' machine (and setting <code>$PVM_ROOT</code> and <code>$PVM_ARCH</code>) is sufficient for running PVM programs. [[compiler|Compiling]] or building PVM programs requires the full PVM installation.

User programs written in [[C (programming language)|C]], [[C++]], or [[Fortran]] can access PVM through provided library routines.

PVM also supports [[broadcasting (computing)|broadcasting]] (PVM_bcast) which sends to all processes in a group and multicasting (PVM_mcast) which sends to a specific list of processes.