HP-UX Workload Manager User's Guide

Configuring WLM
Tuning the metrics and the SLOs
Chapter 5222
Placement of processes for inactive FSS groups
With transient_groups=1, if an FSS workload group, say mygrp, has no
active SLOs, but does have processes assigned to it by user records, Unix
group records, application records, or compartment records, WLM moves
its processes to a temporary group named _IDLE_. This group has only
the minimum CPU and memory resources and can greatly restrict the
progress of a process. When mygrp has active SLOs again, the processes
placed in mygrp by records are moved back to mygrp. However, note that
groups associated with process maps always remain active even if the
groups have no active SLOs.
If a process is not assigned to a group by a record, it is moved to OTHERS
or PRM_SYS if its current group is removed. The process remains in
OTHERS or PRM_SYS even when the group has active SLOs again. For this
reason, be cautious when using only prmrun or prmmove to place a
process in an FSS group that may be removed. Using user records, Unix
group records, application records, or compartment records for processes
that go into transient FSS groups ensures those processes return to the
desired groups when the groups return. (For information on how WLM
determines which group assignment takes precedence when the same
process is identified by multiple records, see “How the application
manager affects workload group assignments” on page 459.)
Placement of processes for PSET-based groups
The placement of processes in a PSET-based group depends on whether
the group has CPU resources (cores) assigned to it. With
transient_groups=1, the group can have zero CPU resources if you
request it or if the group has no active SLOs.
Assume a PSET-based workload group, say mygrp2, has no cores. Any
processes in the group when its last core is taken away, as well as
processes you try to place in the group using prmrun or prmmove when
the group has no cores, are placed in the OTHERS group.
NOTE To minimize the number of processes moved to OTHERS, assign at least
one core to PSET-based groups that have running processes.
When mygrp2 has cores again, the processes placed in mygrp2 by
application records, user records, Unix group records, or compartment
records are moved back to mygrp2. Similarly, any processes you