How Resource Capping Works
The daemon repeatedly samples the resource utilization of projects that have physical memory
caps. The sampling interval used by the daemon is specified by the administrator.
See Determining Sample Intervals for additional information. When the system's physical memory utilization exceeds the
threshold for cap enforcement, and other conditions are met, the daemon takes action
to reduce the resource consumption of projects with memory caps to levels at
or below the caps.
The virtual memory system divides physical memory into segments known as pages. Pages
are the fundamental unit of physical memory in the Solaris memory management subsystem.
To read data from a file into memory, the virtual memory system reads
in one page at a time, or pages in a file. To reduce resource
consumption, the daemon can page out, or relocate, infrequently used pages to a swap
device, which is an area outside of physical memory.
The daemon manages physical memory by regulating the size of a project workload's
resident set relative to the size of its working set. The resident set
is the set of pages that are resident in physical memory. The
working set is the set of pages that the workload actively uses during
its processing cycle. The working set changes over time, depending on the process's
mode of operation and the type of data being processed. Ideally, every workload has
access to enough physical memory to enable its working set to remain
resident. However, the working set can also include the use of secondary disk
storage to hold the memory that does not fit in physical memory.
Only one instance of rcapd can run at any given time.