WLM provides a passive mode that allows you to see how WLM
will approximately respond to a given configuration—without
putting WLM in charge of your system’s resources. Using
this mode, enabled with the -p option to wlmd, you can gain a better understanding of how various WLM
features work. In addition, you can check that your configuration behaves
as expected—with minimal effect on the system.
For example, with passive mode, you can determine:
How does a cpushares statement work?
How do goals work? Is my goal set up correctly?
How might a particular cntl_convergence_rate value or the values of other tunables affect allocation
change?
How does a usage goal work?
Is my global configuration file set up as I wanted?
If I used global arbitration on my production system, what might
happen to the CPU layouts?
Is a user’s default workload group set
up as I expected?
Can a user access a particular workload group?
When an application is run, which workload group
does it run in?
Can I run an application in a particular workload
group?
Are the alternate names for an application set up
correctly?
For more information on how to use the WLM passive mode, as
well as explanations of how passive mode does not always represent
actual WLM operations, see “Trying
a configuration without affecting the system”.
Activate a configuration in passive mode by logging in as
root and running the following command, substituting your configuration
file’s name for config.wlm:
# /opt/wlm/bin/wlmd -p -a config.wlm
The WLM global arbiter, wlmpard, also provides a passive mode. The WLM global
arbiter is used for managing SLOs across virtual partitions and
nPartitions as well as for optimizing Temporary Instant Capacity
(v6 or later) and Pay per use (v4, v7, or later). For more information
on the WLM global arbiter, see Chapter 7 “Managing
SLOs across partitions”.
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