HP-UX Workload Manager User's Guide

How WLM manages workloads
How a workload is managed (controllers)
Chapter 3120
How a workload is managed (controllers)
When a configuration is activated, WLM instantiates a controller for
each SLO that has a performance goal or a usage goal. For SLOs with
usage goals, WLM internally tracks the workload’s actual CPU usage
versus its CPU allocation. With performance goals, controllers receive
metric updates in the form of performance data from data collectors. The
controllers then determine the CPU allocations to request to better
achieve the desired usage or performance goals.
For an illustration showing controllers, see Figure 3-1 on page 115.
For information on specifying usage and performance goals, see
“Specifying a goal (optional)” on page 199.
For information on how to tune controllers, see:
• “Tuning a workload’s SLO convergence: cntl_kp (optional)” page 224
• “Tuning a workload’s SLO convergence: cntl_convergence_rate
(optional)” page 229
• “Tuning the goal buffer (optional)” on page 231
SLO violations
• For usage goals:
An SLO violation occurs if the CPU utilization is above the target
utilization range. With usage goals, the goal is to keep CPU
utilization (CPU used / CPU granted) within a certain range, 50%
and 75% by default. When the workload goes above this range, giving
it more CPU resources can bring it back into the range.
Going below this range is not considered an SLO violation because
the situation cannot be improved by providing the workload with
additional CPU resources.
• For performance goals:
An SLO violation occurs when a workload’s performance varies from
the goal in the wrong direction. Which direction is wrong depends on
the goal definition. For example, if the goal is to keep response_time
less than 5 seconds, a response_time value of 4.3 seconds varies from
the goal in the right direction. However, a response_time value of 5.4