HP PRM Version C.03.04 Release Notes for HP-UX 11i v1, HP-UX 11i v2, and HP-UX 11i v3

PRM Release Notes
Known problems and workarounds
Chapter 120
High CPU load may reduce CPU entitlements of PRM groups with
few processes
Issue
NOTE With Hyper-Threading disabled, each core is seen as a CPU.
With Hyper-Threading enabled, each core can be seen as
multiple, logical CPUs.
The CPU scheduler that PRM uses schedules processes by:
Distributing all the processes from each PRM group in round-robin
fashion starting from the same CPU every time (with the CPUs being
cores or logical CPUs depending on whether Hyper-Threading is
enabled)
Once all the processes are distributed, CPUs with spare cycles inherit
processes from CPUs that are completely busy
Because the round-robin distribution always starts with the same CPU, that
CPUand other CPUs at the start of the distributioncan quickly become
loaded with processes. For example, assume there are many groups with
just one or two processes. Also assume a single PRM group has enough
processes to distribute at least one process per CPU and that each of those
processes consumes all of its CPUs cycles.
As a result, there are no CPUs with spare cycles to inherit processes. With
all those processes crowded on the first CPUs in the round-robin
distribution, the processes associated PRM groups may not be able to get
their CPU entitlements.
Workaround
On HP-UX 11i v1 (B.11.11), install patches PHKL_30034, PHKL_30035,
PHKL_31993, PHKL_31995, and PHKL_32061. Install all these patches at
the same time. For patch descriptions, see HP-UX 11i v1 (B.11.11) patches
on page 13. These patches address CR# JAGae14311.
On HP-UX 11i v2 (B.11.23), install the BUNDLE11i patch bundle. Any
version of this bundle is acceptable.