User guide

IB0054606-02 A 6-1
6 SHMEM Description and
Configuration
Overview
QLogic SHMEM is a user-level communications library for one-sided operations. It
implements the SHMEM Application Programming Interface (API) and runs on the
QLogic IB stack. The SHMEM API provides global distributed shared memory
across a network of hosts. Details of the API implementation are included in an
appendix.
SHMEM is quite distinct from local shared memory (often abbreviated as "shm" or
even “shmem”). Local shared memory is the sharing of memory by processes on
the same host running the same OS system image. SHMEM provides access to
global shared memory distributed across a cluster. The SHMEM API is completely
different from and unrelated to the standard System V Shared Memory API
provided by UNIX operating systems.
Interoperability
QLogic SHMEM depends on the Performance Scaled Messaging (PSM) protocol
layer, implemented as a user-space library. QLogic SHMEM is only available to
run with QLogic IB HCAs.
Installation
SHMEM is packaged with the QLogic IFS or QLogic OFED+ Host software.Every
node in the cluster must have a QLogic IB adapter card and be running RedHat
Enterprise Linux (RHEL) 6, 6.1 or 6.2 OS. One or more Message Passing
Interface (MPI) implementations are required and Performance Scaled Messaging
(PSM) support must be enabled within the MPI. The following MPI
Implementations are supported:
 Open MPI version 1.4.3 configured to include PSM support. This is provided
by QLogic IFS and can be found in the following directories:
/usr/mpi/gcc/openmpi-1.4.3-qlc
/usr/mpi/intel/openmpi-1.4.3-qlc
/usr/mpi/pgi/openmpi-1.4.3-qlc