Using HP-UX Workload Manager: A quick reference

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NOTE
WLM adjusts only a workload group’s CPU allocation in response to SLO
performance. Thus, WLM SLO management is most effective for workloads
that are CPU-bound.
How do I put an application under HP-UX Workload
Manager control?
WLM can treat an nPartition or virtual partition as a workload. The workload consists of all the
processes running in the operating system instance on the partition. WLM also enables you to divide
the resources of a single operating system into pSets or FSS groups. When dividing the resources of a
single operating system, the workloads are known as “workload groups.”
If you will not be using WLM to manage resources within a single HP-UX image, you can omit the rest
of this section and go to the “How do I determine a goal for my workload?” section on page 17.
When a system is divided into workload groups, each application must go into a workload group. By
default, processes run by root users go into the PRM_SYS group, and processes run by non-root users
go into the OTHERS group. However, you can change the workload group in which a particular
user’s processes run by adding user records to the WLM configuration file. You can add Unix group
records to the configuration file so that the processes running in a specified Unix group are placed in
a specific workload group. Furthermore, you can specify the workload groups in which processes run
by adding application records to your WLM configuration, or defining secure compartments that
isolate the processes in specified workload groups. You can even define process maps that include
your own criteria for placing processes in workload groups.
When determining the workload groups where particular processes should be placed, WLM gives
application records precedence over user records, and user records precedence over Unix group
records. For example, if the same process is identified in both application records and user records,
the process is placed in the workload group assigned to it by the application record. If you define
secure compartments, they take precedence over application, user, and Unix grouip records. If you
define process maps, they take precedence over all the WLM records. In addition, you can alter the
workload group of an application using the prmmove and prmrun utilities, which are discussed in
the following sections.
As you can see, WLM provides several methods for placing processes in workload groups. It is
important to understand these methods because they form the basis of the workload separation.
First, define the workload groups for the workloads. The following snippet from a WLM configuration
file creates three workload groups: servers_grp, apache_grp, and OTHERS. (The OTHERS group
is a reserved workload group and must have ID 1. If you do not explicitly create this group, WLM will
create it for you.)
prm {
groups = OTHERS : 1,
servers_grp : 2,
apache_grp : 3;
}
Each workload group is given a name and a number. Later sections of the WLM configuration file
assign resources to the groups. Processes within the groups then share the resources allocated to that
group.