HP SVA V2.1 Parallel Compositing Reference Guide

int flag=1;
setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char*)&flag, sizeof(int));
• HP Remote Graphics Software (RGS) Impacts Performance
If you are connected to a node using RGS and that node is using the Library to either render
or display, RGS also needs to read back pixels from the graphics card’s framebuffer. This
competes for resources with rendering and readback.
Similarly, there is a performance loss if you point the X Display of a node using the Library
to another machine over the network.
• Limits in the HP Implementation
— A host may contribute 0..9 framelets. This limit is quite arbitrary; however, if you think
you need more framelets, review the behavior of the multiple-frames sample. You
may decide that adding too many additional framelets comes at the expense of
performance.
— The maximum value for PC_FRAME_WIDTH and PC_FRAME_HEIGHT is 65,536. That is
more than 4.2 billion pixels.
— The maximum size of a framelet is 4096 x 4096. An OpenGL window has a similar limit.
Loading Network Layers
The ParaComp Library works with various network layers. The HP implementation comes with
three network layers:
• TCP sockets.
• A native IB layer based on the Mellanox-VAPI stack.
• A native IB layer based on the Open Fabrics Enterprise Distribution (OFED) stack.
An HP XC-based cluster (including SVA) typically has two networks that connect the nodes in
the cluster:
• A gigabit Ethernet administration network.
• A higher-speed interconnect network that can be gigabit Ethernet, InfiniBand, Quadrics,
and so on.
When your application creates a context, it specifies the network to use. Typically, an application
asks for the default. In this case, the Library checks for the available network layers and chooses
the fastest one. For example, the Library uses an InfiniBand interconnect, if available. For other
interconnects, the Library uses TCP over your interconnect.
HP SVA can be configured with either a VAPI or OFED InfiniBand stack. The Library supports
both and determines at run time the library to load by reading the pclib.conf file. This file is
the directory specified by the PC_LIBRARY_PATH environment variable (default value is
/opt/paracomp/lib64).
24 Main Areas of the Parallel Compositing Library