HP-UX Workload Manager User's Guide

Configuring WLM
Tuning the metrics and the SLOs
Chapter 5 227
Use the optional cntl_kp tunable to tune convergence. It can be used in
global, metric-specific, and metric/SLO-specific tune structures. Its
syntax is:
cntl_kp = proportional_term;
where
proportional_term
Is a floating-point value between 0 and 1,000,000
(inclusive) used on the proportional term in the
controller’s expression. The default value is 1.
Change this value according to how sensitive the SLO’s
associated workload is to changes in CPU allocation
and based on the magnitude of the goal being
measured.
Recall the formula for determining new allocation
requests:
New CPU allocation =
(Allocation last interval) + cntl_kp * P
If P is typically large, say 10 or 100 or higher, use a
smaller cntl_kp to scale down the cntl_kp * P result
so it does not overcorrect. Similarly, for very small
values of P (less than 1), use cntl_kp to scale up the
cntl_kp * P result.
If WLM changes allocations too rapidly, resulting in
instability, decrease proportional_term. If WLM
changes allocations too slowly, increase
proportional_term.
With absolute CPU units enabled
(absolute_cpu_units = 1), your
proportional_term maintains more predictable
behavior from your workload regardless of the number
of available cores. Without absolute CPU units, the
effect of a given proportional_term depends on the
number of available cores, which could produce
undesirable effects. HP recommends enabling absolute
CPU units.