HP PRM Version C.03.05 Release Notes for HP-UX 11i v1, HP-UX 11i v2, and HP-UX 11i v3

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
CPU—and other CPUs at the start of the distribution—can 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 CPU’s 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”
(page 14). 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.
Unable to achieve CPU entitlement due to number of processes
Issue PRM provides a PRM group its entitlement on an SMP system with
Hyper-Threading disabled by granting the group its entitlement on each core.
If the group does not have at least one process for each core, PRM compensates
by proportionally increasing the PRM group’s entitlements on cores where it
does have processes. For example, for a PRM group with a single-threaded
process, a 10% entitlement of four cores results in a 40% entitlement on one
core.
Assume this same PRM group were allocated 50% of the four cores. PRM would
give the group an entitlement of 100% on two cores. However, because the
group has only the one thread, it can use only one core, resulting in a 25%
entitlement.
Workaround There is no workaround. However, be aware of how your applications run so
that you do not give them resource entitlements they cannot use.
Secure Resource Partitions: Blocked port on a virtual network interface
Issue Using the optional HP-UX feature Security Containment, you can set up a virtual
network interface for each secure compartment. A process in one secure
compartment can bind to a socket on a virtual network interface associated with
a different secure compartment. Although this process will not be able to accept
High CPU load may reduce CPU entitlements of PRM groups with few processes 19