AIX 5L Problem Determination - IBM Redbooks

process belongs to (when not shared, or shared by processes in the same
superclass) or to the Shared superclass, when shared by processes in
different superclasses. However, there are a few pages that cannot be
directly tied to any processes (and thus to any class) at the time of this
classification, and this memory is charged to the Unclassified superclass; for
example, pages from a file that has been closed. The file pages will remain in
memory, but no process owns these pages; therefore, they cannot be
charged to a specific class. Most of this memory will end up being correctly
reclassified over time, when it is either accessed by a process, or freed and
reallocated to a process after WLM is started. There are a few kernel
processes, such as wait or Irud, in the Unclassified superclass. Even though
this superclass can have physical memory shares and limits applied to it,
WLM commands do not allow you to set shares and limits or specify
subclasses or assignment rules on this superclass.
► Unmanaged superclass: A special superclass named Unmanaged will always
be defined. No processes will be assigned to this class. This class will be
used to accumulate the memory usage for all pinned pages in the system that
are not managed by WLM. The CPU utilization for the waitprocs is not
accumulated in any class. This is deliberate; otherwise, the system would
always seem to be at 100 percent CPU utilization, which could be misleading
for users when looking at the WLM or system statistics. This superclass
cannot have shares or limits for any other resource types, subclasses, or
assignment rules specified.
Subclasses
A subclass is a class associated with exactly one superclass. Every process in
the subclass is also a member of the superclass. Subclasses only have access
to resources that are available to the superclass. A subclass has a set of class
assignment rules that determine which of the processes assigned to the
superclass will belong to it. A subclass also has a set of resource limitation
values and resource target shares that determine the resources that can be used
by processes in the subclass. These resource limitation values and resource
target shares indicate how much of the superclass’s target (the resources
available to the superclass) can be used by processes in the subclass.
Up to 10 out of a total of 12 subclasses can be defined by the system
administrator or by the superclass administrator for each superclass. In addition,
two special subclasses, Default and Shared, are always defined in each
superclass as follows:
► Default subclass: The default subclass is named Default and is always
defined. All processes that are not automatically assigned to a specific
subclass of the superclass will be assigned to the Default subclass. You can
also assign other processes to the Default subclass by providing specific
assignment rules.
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