IBM Power Systems 775 Manual page 105

Active Messaging Interface: Beginning with Parallel Environment Runtime Edition
version 1.1 for AIX, the low-level application programming interface (LAPI) was replaced by
a new messaging API called the
supported only point-to-point communications and PAMI supports both point-to-point and
collective communications.
This change means that PE MPI now runs on top of PAMI. Existing calls to LAPI
point-to-point functions are replaced by PAMI point-to-point functions, and some collectives
are replaced by PAMI collectives.
LAPI is still supported by PE. However, because LAPI no longer receives any functional
enhancements, and PE removes support for LAPI, users must migrate from LAPI to PAMI.
For more information about installing LAPI or PAMI, see Parallel Environment Runtime
Edition for AIX V1.1: Installation, SC23-6780. For more information about migrating from
LAPI to PAMI, and about PAMI in general, see the IBM Parallel Environment Runtime
Edition: PAMI Programming Guide, SA23-2273.
MPI and LAPI provide communication between parallel tasks, enabling application programs
parallelized
to be .
MPI provides message passing capabilities that enable parallel tasks to communicate data
and coordinate execution. The message passing routines call communication subsystem
library routines to handle communication among the processor nodes.
LAPI differs from MPI in that LAPI is based on an
provides a one-sided communications model in which one process initiates an operation. The
completion of that operation does not require any other process to take a complementary
action. LAPI also is the common transport layer for MPI and is packaged as part of the AIX
RSCT component.
Parallel Environment debug environment
The parallel debugger (pdb) streamlines debugging of parallel applications, presenting the
user with a single command line interface that supports most dbx/gdb execution control
commands and the ability to examine running tasks. To simplify the management of a large
numbers of tasks, dbx/gdb grpups tasks together so that the user might examine any subset
of the debugged tasks.
PDB allows users to invoke a POE job or attach to a running POE job and place it under
debug control. pdb starts a remote dbx/gdb session for each task of the POE job that is
placed under debugger control.
PDB provides advanced features, including: dynamic tasking support, multiple console
display, and output filtering.
parallel active messaging interface
active message style
Chapter 1. Understanding the IBM Power Systems 775 Cluster
(PAMI). LAPI
mechanism that
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