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Oracle Solaris 11.1 Administration: Oracle Solaris Zones, Oracle Solaris 10 Zones, and Resource Management     Oracle Solaris 11.1 Information Library
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Part I Oracle Solaris Resource Management

1.  Introduction to Resource Management

2.  Projects and Tasks (Overview)

3.  Administering Projects and Tasks

4.  Extended Accounting (Overview)

5.  Administering Extended Accounting (Tasks)

6.  Resource Controls (Overview)

7.  Administering Resource Controls (Tasks)

8.  Fair Share Scheduler (Overview)

9.  Administering the Fair Share Scheduler (Tasks)

10.  Physical Memory Control Using the Resource Capping Daemon (Overview)

Introduction to the Resource Capping Daemon

How Resource Capping Works

Attribute to Limit Physical Memory Usage for Projects

rcapd Configuration

Using the Resource Capping Daemon on a System With Zones Installed

Memory Cap Enforcement Threshold

Determining Cap Values

rcapd Operation Intervals

Determining rcapd Scan Intervals

Determining Sample Intervals

Monitoring Resource Utilization With rcapstat

Commands Used With rcapd

11.  Administering the Resource Capping Daemon (Tasks)

12.  Resource Pools (Overview)

13.  Creating and Administering Resource Pools (Tasks)

14.  Resource Management Configuration Example

Part II Oracle Solaris Zones

15.  Introduction to Oracle Solaris Zones

16.  Non-Global Zone Configuration (Overview)

17.  Planning and Configuring Non-Global Zones (Tasks)

18.  About Installing, Shutting Down, Halting, Uninstalling, and Cloning Non-Global Zones (Overview)

19.  Installing, Booting, Shutting Down, Halting, Uninstalling, and Cloning Non-Global Zones (Tasks)

20.  Non-Global Zone Login (Overview)

21.  Logging In to Non-Global Zones (Tasks)

22.  About Zone Migrations and the zonep2vchk Tool

23.  Migrating Oracle Solaris Systems and Migrating Non-Global Zones (Tasks)

24.  About Automatic Installation and Packages on an Oracle Solaris 11.1 System With Zones Installed

25.  Oracle Solaris Zones Administration (Overview)

26.  Administering Oracle Solaris Zones (Tasks)

27.  Configuring and Administering Immutable Zones

28.  Troubleshooting Miscellaneous Oracle Solaris Zones Problems

Part III Oracle Solaris 10 Zones

29.  Introduction to Oracle Solaris 10 Zones

30.  Assessing an Oracle Solaris 10 System and Creating an Archive

31.  (Optional) Migrating an Oracle Solaris 10 native Non-Global Zone Into an Oracle Solaris 10 Zone

32.  Configuring the solaris10 Branded Zone

33.  Installing the solaris10 Branded Zone

34.  Booting a Zone, Logging in, and Zone Migration



rcapd Configuration

You use the rcapadm command to configure the resource capping daemon. You can perform the following actions:

To configure the daemon, you must be the root user or have the required administrative rights.

Configuration changes can be incorporated into rcapd according to the configuration interval (see rcapd Operation Intervals) or on demand by sending a SIGHUP (see the kill(1) man page).

If used without arguments, rcapadm displays the current status of the resource capping daemon if it has been configured.

The following subsections discuss cap enforcement, cap values, and rcapd operation intervals.

Using the Resource Capping Daemon on a System With Zones Installed

You can control resident set size (RSS) usage of a zone by setting the capped-memory resource when you configure the zone. For more information, see Physical Memory Control and the capped-memory Resource. To use the capped-memory resource, the resource-cap package must be installed in the global zone. You can run rcapd within a zone, including the global zone, to enforce memory caps on projects in that zone.

You can set a temporary cap for the maximum amount of memory that can be consumed by a specified zone, until the next reboot. See How to Specify a Temporary Resource Cap for a Zone.

If you are using rcapd on a zone to regulate physical memory consumption by processes running in projects that have resource caps defined, you must configure the daemon in those zones.

When choosing memory caps for applications in different zones, you generally do not have to consider that the applications reside in different zones. The exception is per-zone services. Per-zone services consume memory. This memory consumption must be considered when determining the amount of physical memory for a system, as well as memory caps.

Memory Cap Enforcement Threshold

The memory cap enforcement threshold is the percentage of physical memory utilization on the system that triggers cap enforcement. When the system exceeds this utilization, caps are enforced. The physical memory used by applications and the kernel is included in this percentage. The percentage of utilization determines the way in which memory caps are enforced.

To enforce caps, memory can be paged out from project workloads.

A workload is permitted to use physical memory up to its cap. A workload can use additional memory as long as the system's memory utilization stays below the memory cap enforcement threshold.

To set the value for cap enforcement, see How to Set the Memory Cap Enforcement Threshold.

Determining Cap Values

If a project cap is set too low, there might not be enough memory for the workload to proceed effectively under normal conditions. The paging that occurs because the workload requires more memory has a negative effect on system performance.

Projects that have caps set too high can consume available physical memory before their caps are exceeded. In this case, physical memory is effectively managed by the kernel and not by rcapd.

In determining caps on projects, consider these factors.

Impact on I/O system

The daemon can attempt to reduce a project workload's physical memory usage whenever the sampled usage exceeds the project's cap. During cap enforcement, the swap devices and other devices that contain files that the workload has mapped are used. The performance of the swap devices is a critical factor in determining the performance of a workload that routinely exceeds its cap. The execution of the workload is similar to running it on a machine with the same amount of physical memory as the workload's cap.

Impact on CPU usage

The daemon's CPU usage varies with the number of processes in the project workloads it is capping and the sizes of the workloads' address spaces.

A small portion of the daemon's CPU time is spent sampling the usage of each workload. Adding processes to workloads increases the time spent sampling usage.

Another portion of the daemon's CPU time is spent enforcing caps when they are exceeded. The time spent is proportional to the amount of virtual memory involved. CPU time spent increases or decreases in response to corresponding changes in the total size of a workload's address space. This information is reported in the vm column of rcapstat output. See Monitoring Resource Utilization With rcapstat and the rcapstat(1) man page for more information.

Reporting on shared memory

The rcapd daemon reports the RSS of pages of memory that are shared with other processes or mapped multiple times within the same process as a reasonably accurate estimate. If processes in different projects share the same memory, then that memory will be counted towards the RSS total for all projects sharing the memory.

The estimate is usable with workloads such as databases, which utilize shared memory extensively. For database workloads, you can also sample a project's regular usage to determine a suitable initial cap value by using output from the -J or -Z options of the prstat command. For more information, see the prstat(1M) man page.

rcapd Operation Intervals

You can tune the intervals for the periodic operations performed by rcapd.

All intervals are specified in seconds. The rcapd operations and their default interval values are described in the following table.

Default Interval Value in Seconds
Number of seconds between scans for processes that have joined or left a project workload. Minimum value is 1 second.
Number of seconds between samplings of resident set size and subsequent cap enforcements. Minimum value is 1 second.
Number of seconds between updates to paging statistics. If set to 0, statistics are not updated, and output from rcapstat is not current.
Number of seconds between reconfigurations. In a reconfiguration event, rcapadm reads the configuration file for updates, and scans the project database for new or revised project caps. Sending a SIGHUP to rcapd causes an immediate reconfiguration.

To tune intervals, see How to Set Operation Intervals.

Determining rcapd Scan Intervals

The scan interval controls how often rcapd looks for new processes. On systems with many processes running, the scan through the list takes more time, so it might be preferable to lengthen the interval in order to reduce the overall CPU time spent. However, the scan interval also represents the minimum amount of time that a process must exist to be attributed to a capped workload. If there are workloads that run many short-lived processes, rcapd might not attribute the processes to a workload if the scan interval is lengthened.

Determining Sample Intervals

The sample interval configured with rcapadm is the shortest amount of time rcapd waits between sampling a workload's usage and enforcing the cap if it is exceeded. If you reduce this interval, rcapd will, under most conditions, enforce caps more frequently, possibly resulting in increased I/O due to paging. However, a shorter sample interval can also lessen the impact that a sudden increase in a particular workload's physical memory usage might have on other workloads. The window between samplings, in which the workload can consume memory unhindered and possibly take memory from other capped workloads, is narrowed.

If the sample interval specified to rcapstat is shorter than the interval specified to rcapd with rcapadm, the output for some intervals can be zero. This situation occurs because rcapd does not update statistics more frequently than the interval specified with rcapadm. The interval specified with rcapadm is independent of the sampling interval used by rcapstat.