HP Process Resource Manager User's Guide

Understanding how PRM manages resources
How PRM manages CPU resources
Chapter 246
At Time B:
• Group1’s processes are now using 80% of available CPU time, which
consists of all of Group1’s shares and an unused portion of Group2’s
share.
• Group2 processes continue at a steady 15%.
• PRM scheduling is not in effect.
Between Time B and Time C:
• Group2’s demands start to increase.
• With available CPU resource use approaching 100%, PRM starts to
have an effect on CPU allocation.
• Both groups’ CPU resource use begins moving toward their assigned
number of shares. In this case, the increasing demand of Group2
causes Group1 to be pulled toward the 33% mark despite its desire
for more CPU resources.
At Time C:
• CPU resource use for Group1 and Group2 is limited to the assigned
shares.
After Time C:
PRM holds each group to its assigned available CPU resource percentage
until total available CPU resource demand is less than 100%. This gives
Group2 a priority for CPU resources over Group1. In contrast, in the
standard HP-UX scheduler, CPU time is allocated based upon the
assumption that all processes are of equal importance. Assuming there is
one process associated with each PRM group, the standard HP-UX
scheduler would allocate each process 50% of the available CPU
resources after Time C.