HP Process Resource Manager User's Guide

Understanding how PRM manages resources
How resource allocations interact
Chapter 2 59
How resource allocations interact
You can assign different numbers of shares for CPU (for FSS PRM
groups), memory, and disk bandwidth resources to a PRM group
depending on the group’s requirements for each type of resource. To
optimize resource use, it is important to understand the typical demands
for resources within a PRM group.
For example, suppose the DesignTool application is assigned to PRM
group DTgroup, and it is the only application running in that group.
Suppose also that the DesignTool application uses CPU and memory
resources in an approximate ratio of two to three. For optimal results,
you should assign the resource shares for DTgroup in the same ratio. For
example, assign 10 CPU shares and 15 memory shares or 20 CPU shares
and 30 memory shares.
If the percentages assigned do not reflect actual usage, then a PRM
group may not be able to fully utilize a resource to which it is entitled.
For instance, assume you assign 50 CPU shares and 30 memory shares
to DTgroup. At times of peak system load, DTgroup is able to use only
approximately 20 CPU shares (although it is assigned 50 shares)
because it is limited to 30 memory shares. (Recall that DesignTool uses
CPU and memory resources at a ratio of two to three.) Conversely, if
DTgroup is assigned 10 CPU shares and 30 memory shares, then at times
of peak system load, DTgroup is only able to utilize 15 memory shares
(not its 30 shares), because it is restricted to 10 CPU shares.
To use system resources in the most efficient way, monitor typical
resource use in PRM groups and adjust shares accordingly. You can
monitor resource use with the prmanalyze command, the prmmonitor
command, or the optional HP product GlancePlus. For more information
on prmmonitor, see the prmmonitor(1) manpage.
For prmanalyze syntax information, see the section “prmanalyze” on
page 203. For usage examples, see “Using prmanalyze to quickly identify
resource use” on page 81 and “Using prmanalyze to analyze your
configuration” on page 162.