HP Scalable Visualization Array Software - Manual (Page 54)

Reference Guide describe how to use launch templates to run applications, including the underlying
functions and commands contained in the script.
6.3 Running a Workstation Application Using a Multi-Tile Display
This section describes how to run a serial workstation application on the SVA using Chromium
and DMX.
6.3.1 Assumptions and Goal
This example assumes you have a visualization application that currently runs on a single
workstation. It also assumes that you have not specifically modified it to take advantage of the
parallel features of a cluster.
This example also assumes that your goal is to run the application on the SVA and to take
advantage of the multi-tile capabilities of the cluster.
6.3.2 Chromium Overview and Usage Notes
Chromium creates a way for many programs using the OpenGL standard to take advantage of
cluster technology by automatically distributing OpenGL. Chromium provides a common parallel
graphics programming interface to support clusters such as the SVA. In addition, it enables many
existing applications to display on multiple tiles without modification.
Chromium provides the following features:
• A method for synchronizing parallel graphics commands.
• Streaming graphics pipeline based on the industry standard OpenGL API.
• Support for multiple physical display devices clustered together, such as powerwall displays.
• Support for aggregation of the output of multiple graphics cards to drive a single display
at higher levels of performance and capability.
Chromium is automatically installed and configured on the SVA in several ways of interest to
application developers:
• Autostart is not used.
• CR-Servers and CR Mothership are launched by the SVA launch script. See Section 6.3.7 .
• Tile information is taken from the SVA Configuration Data Files, which eliminates the need
to hard code this information in the Chromium configuration files.
• Chromium uses tilesort and TCP/IP over the SI for DMX and Chromium connections.
• There is a ten second delay between the time that the Mothership and Clients launch. This
adds a brief delay to the startup time.
Although Chromium has several configuration files that you typically need to edit, the SVA
launch script eliminates this need by using configuration data from the SVA Configuration Data
Files.
A link to the Chromium documentation is available from the SVA Documentation Library.
6.3.3 Distributed Multi-Head X (DMX)
Xdmx is a proxy X Server that provides multi-head support for multiple displays attached to
different machines (each of which is running a typical X Server). A simple application of Xdmx
provides multi-head support using two desktop machines, each of which has a single display
device attached to it. A complex application of Xdmx unifies a four by four grid of 1280x1024
displays, each attached to one of 16 computers, into a unified 5120x4096 display.
The front end proxy X Server removes the limit on the number of physical devices that can coexist
in a single machine (for example, due to the number of PCI-Express slots available for graphics
cards). Thus, large tiled displays are possible.
A link to the DMX documentation is available from the SVA Documentation Library.
54 Application Examples