man pages section 4: File Formats

power.conf(4)

Name

power.conf– Power Management configuration information file

Synopsis

/etc/power.conf

Description

The power.conf file is used by the Power Management configuration program pmconfig(1M), to initialize the settings for Power Management. If you make changes to this file, you must run pmconfig(1M) manually for the changes to take effect.

The dtpower(1M) GUI allows the configuration of a subset of parameters allowed by this file. For ease-of-use, it is recommended that you use dtpower(1M) to configure the parameters. See the EXAMPLES section for information on disabling Power Management.

Power Management addresses two specific management scenarios: management of individual devices and management of the whole system. An individual device is power managed if the device supports multiple power levels and if the device driver uses Power Management interfaces provided by the kernel to save device power when the device is idle.

All entries in the power.conf file are processed in the order that they occur in the file.

Automatic Device Power Management

Devices with drivers that use the automatic device Power Management interfaces are automatically power managed if the autopm entry is enabled. The autopm entry is described near the end of this section. The pm-components property describes the Power Management model of a device driver to the Power Management framework. See pm-components(9P) for more information.

When a component has been idle at a given power level for its threshold time, the power level of the component will be reduced to the next lower power level of that component, if any. For devices which implement multiple components, each component is power-managed independently.

Default thresholds for components of automatically power managed devices are computed by the Power Management framework based on the system idleness threshold. By default, all components of the device are powered off if they have all been idle for the system's idleness threshold. The default system idleness threshold is determined by the applicable United States Environmental Protection Agency's (EPA) Energy Star Memorandum of Understanding. See the NOTES section of this manual page for more information.

To set the system idleness threshold, use one of the following entries:

system-threshold     threshold

system-threshold    always-on

where threshold is the value of the system idleness threshold in hours, minutes or seconds as indicated by a trailing h, m or s (defaulting to seconds if only a number is given). If always-on is specified, then by default, all devices will be left at full power.

The system-threshold entry is applicable to CPU Power Management only when CPU Power Management has been configured to operate in poll-mode, which is expressed through the cpupm keyword.

If a system has power manageable CPUs, these may be managed independently of the system idleness threshold by using one of the following entries:

cpu-threshold    threshold

cpu-threshold    always-on

where threshold is the value of the CPU idleness threshold in hours, minutes or seconds as indicated by a trailing h, m or s (defaulting to seconds if only a number is given). If always-on is specified, then by default, all CPUs will be left at full power.

The cpu-threshold keyword is used only when CPU Power Management has been configured to operate in poll-mode, which is expressed through the cpupm keyword.

If no cpu-threshold entry is specified, then the system idleness threshold will be used.

To override the default device component thresholds assigned by the Power Management framework, a device-thresholds entry may be used. A device-thresholds entry sets thresholds for a specific automatically power-managed device or disables automatic Power Management for the specific device.

A device-thresholds entry has the form:

device-thresholds     phys_path   (threshold ...) ...

device-thresholds     phys_path   threshold

device-thresholds     phys_path   always-on

where phys_path specifies the physical path (libdevinfo(3LIB)) of a specific device. For example, /pci@8,600000/scsi@4/ssd@w210000203700c3ee,0 specifies the physical path of a disk. A symbolic link into the /devices tree, for example /dev/dsk/c1t1d0s0, is also accepted. The thresholds apply (or keeping the device always on applies) to the specific device only.

In the first form above, each threshold value represents the number of hours, minutes or seconds, depending on a trailing h, m or s with a default to seconds, to spend idle at the corresponding power level before power will be reduced to the next lower level of that component. Parentheses are used to group thresholds per component, with the first (leftmost) group being applied to component 0, the next to component 1, and the like. Within a group, the last (rightmost) number represents the time to be idle in the highest power level of the component before going to the next-to-highest level, while the first (leftmost) number represents the time to be idle in the next-to-lowest power level before going to the lowest power level.

If the number of groups does not match the number of components exported by the device (by means of pm-components(9P) property), or the number of thresholds in a group is not one less than the number of power levels the corresponding component supports, then an error message will be printed and the entry will be ignored.

For example, assume a device called xfb exports the components Frame Buffer and Monitor. Component Frame Buffer has two power levels: Off and On. Component Monitor has four power levels: Off, Suspend, Standby, and On.

The following device-thresholds entry:

device-thresholds  /pci@f0000/xfb@0    (0) (3m 5m 15m)

would set the threshold time for the Monitor component of the specific xfb card to go from On to Standby in 15 minutes, the threshold for Monitor to go from Standby to Suspendin 5 minutes, and the threshold for Monitor to go from Suspend to Off in 3 minutes. The threshold for Frame Buffer to go from On to Off will be 0 seconds.

In the second form above, where a single threshold value is specified without parentheses, the threshold value represents a maximum overall time within which the entire device should be powered down if it is idle. Because the system does not know about any internal dependencies there may be among a device's components, the device may actually be powered down sooner than the specified threshold, but will not take longer than the specified threshold, provided that all device components are idle.

In the third form above, all components of the device are left at full power.

Device Power Management entries are only effective if there is no user process controlling the device directly. For example, X Windows systems directly control frame buffers. The entries in the power.conf file are effective only when X Windows is not running.

Dependencies among devices may also be defined. A device depends upon another if none of its components may have their power levels reduced unless all components of the other device are powered off. A dependency may be indicated by an entry of the form:

device-dependency dependent_phys_path phys_path [ phys_path ... ]

where dependent_phys_path is the path name (as above) of the device that is kept up by the others, and the phys_path entries specify the devices that keep it up. A symbolic link into the /devices tree, such as /dev/fb, is also accepted. This entry is needed only for logical dependents for the device. A logical dependent is a device that is not physically connected to the power managed device (for example, the display and the keyboard). Physical dependents are automatically considered and need not be included.

In addition to listing dependents by physical path, an arbitrary group of devices can be made dependent upon another device by specifying a property dependency using the following syntax:

device-dependency-property property phys_path [phys_path ...]

where each device that exports the property property will be kept up by the devices named by phys_path(s). A symbolic link into the /devices tree (such as /dev/fb) is accepted as well as a pathname for phys_path.

For example, the following entry ensures that every device that exports the boolean property named removable-media is kept up when the console framebuffer is up. See removable-media(9P).

# This entry keeps removable media from being powered down unless the
# console framebuffer and monitor are powered down
# (See removable-media(9P))
#
device-dependency-property removable-media /dev/fb

An autopm entry may be used to enable or disable automatic device Power Management on a system-wide basis. The format of the autopm entry is:

autopm behavior

Acceptable behavior values are described in the following:

default: The behavior of the system will depend upon its model. Desktop models that fall under the United States Environmental Protection Agency's Energy Star Memorandum of Understanding #3 will have automatic device Power Management enabled, and all others will not. See the NOTES section of this manual page for more information.
enable: Automatic device Power Management will be started when this entry is encountered.
disable: Automatic device Power Management will be stopped when this entry is encountered.

A cpupm entry may be used to enable or disable Power Management of CPUs on a system-wide basis, independent of autopm. The format of the cpupm entry is:

cpupm behavior

Acceptable behavior values and their meanings are :

enable

CPU Power Management will be started when this entry is encountered.

Where the behavior is enable, an optional mode argument can be specified:

cpupm enable mode

Acceptable mode values and their meanings are:

event-mode: CPU power state transitions is driven by thread scheduler/dispatcher events. The cpu-threshold, and system-threshold keywords are not used for CPUs in this mode.
poll-mode: The Power Management framework polls the idleness of the system's CPUs, and manages their power once idle for the period of time specified by either the system-threshold or cpu-threshold.

disable

CPU Power Management will be stopped when this entry is encountered.

If supported by the platform, a cpu_deep_idle entry can be used to enable or disable automatic use of power saving cpu idle states. The format of the cpu_deep_idle entry is:

cpu_deep_idle behavior

Acceptable values for behavior are:

default: Advanced cpu idle power saving features are enabled on hardware which supports it. On X86 systems this can translate to the use of ACPI C-States beyond C1.
enable: Enables the system to automatically use idle cpu power saving features.
disable: The system does not automatically use idle cpu power saving features. This option can be used when maximum performance is required at the expense of power.
absent: It the cpu_deep_idle keyword is absent from power.conf the behavior is the same as the default case.

System Power Management

The system Power Management entries control Power Management of the entire system using the suspend-resume feature. When the system is suspended, the complete current state is saved on the disk before power is removed. On reboot, the system automatically starts a resume operation and the system is restored to the state it was in prior to suspend.

The system can be configured to do an automatic shutdown (autoshutdown) using the suspend-resume feature by an entry of the following form:

autoshutdown idle_time start_time finish_time behavior

idle_time specifies the time in minutes that system must have been idle before it will be automatically shutdown. System idleness is determined by the inactivity of the system and can be configured as discussed below.

start_time and finish_time (each in hh:mm) specify the time period during which the system may be automatically shutdown. These times are measured from the start of the day (12:00 a.m.). If the finish_time is less than or equal to the start_time, the period span from midnight to the finish_time and from the start_time to the following midnight. To specify continuous operation, the finish_time may be set equal to the start_time.

Acceptable behavior values are described in the following:

shutdown: The system will be shut down automatically when it has been idle for the number of minutes specified in the idle_time value and the time of day falls between the start_time and finish_time values.
noshutdown: The system is never shut down automatically.
autowakeup: If the hardware has the capability to do autowakeup, the system is shut down as if the value were shutdown and the system will be restarted automatically the next time the time of day equals finish_time.
default: The behavior of the system will depend upon its model. Desktop models that fall under the United States Environmental Protection Agency's Energy Star Memorandum of Understanding #2 will have automatic shutdown enabled, as if behavior field were set to shutdown, and all others will not. See NOTES.
unconfigured: The system will not be shut down automatically. If the system has just been installed or upgraded, the value of this field will be changed upon the next reboot.

You can use the following format to configure the system's notion of idleness:

idleness_parameter value

Where idleness_parameter can be:

ttychars

If the idleness_parameter is ttychars, the value field will be interpreted as the maximum number of tty characters that can pass through the ldterm module while still allowing the system to be considered idle. This value defaults to 0 if no entry is provided.

loadaverage

If the idleness_parameter is loadaverage, the (floating point) value field will be interpreted as the maximum load average that can be seen while still allowing the system to be considered idle. This value defaults to 0.04 if no entry is provided.

diskreads

If the idleness_parameter is diskreads, the value field will be interpreted as the maximum number of disk reads that can be perform by the system while still allowing the system to be considered idle. This value defaults to 0 if no entry is provided.

nfsreqs

If the idleness_parameter is nfsreqs, the value field will be interpreted as the maximum number of NFS requests that can be sent or received by the system while still allowing the system to be considered idle. Null requests, access requests, and getattr requests are excluded from this count. This value defaults to 0 if no entry is provided.

idlecheck

If the idleness_parameter is idlecheck, the value must be pathname of a program to be executed to determine if the system is idle. If autoshutdown is enabled and the console keyboard, mouse, tty, CPU (as indicated by load average), network (as measured by NFS requests) and disk (as measured by read activity) have been idle for the amount of time specified in the autoshutdown entry specified above, and the time of day falls between the start and finish times, then this program will be executed to check for other idleness criteria. The value of the idle time specified in the above autoshutdown entry will be passed to the program in the environment variable PM_IDLETIME. The process must terminate with an exit code that represents the number of minutes that the process considers the system to have been idle.

There is no default idlecheck entry.

When the system is suspended, the current system state is saved on the disk in a statefile. An entry of following form can be used to change the location of statefile:

statefile pathname

where pathname identifies a block special file, for example, /dev/dsk/c1t0d0s2, or is the absolute pathname of a local ufs file. If the pathname specifies a block special file, it can be a symbolic link as long as it does not have a file system mounted on it. If pathname specifies a local ufs file, it cannot be a symbolic link. If the file does not exist, it will be created during the suspend operation. All the directory components of the path must already exist.

The actual size of statefile depends on a variety of factors, including the size of system memory, the number of loadable drivers/modules in use, the number and type of processes running, and the amount of user memory that has been locked down. It is recommended that statefile be placed on a file system with at least 10 Mbytes of free space. In case there is no statefile entry at boot time, an appropriate new entry is automatically created by the system.

Examples

Example 1 Disabling Automatic Device Power Management

To disable automatic device Power Management, change the following line in the /etc/power.conf file

autopm	default

to read:

autopm	disable

Then run pmconfig or reboot. See pmconfig(1M) for more information.

You can also use dtpower to disable automatic device Power Management. See dtpower(1M) for more information.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWpmr
Interface Stability	Committed

Notes

SPARC desktop models first shipped after October 1, 1995 and before July 1, 1999 comply with the United States Environmental Protection Agency's Energy Star Memorandum of Understanding #2 guidelines and have autoshutdown enabled by default after 30 minutes of system idleness. This is achieved by default keyword of autoshutdown entry behave as shutdown for these machines. The user is prompted to confirm this default behavior at system installation reboot, or during the first reboot after the system is unconfigured by sys-unconfig(1M).

SPARC desktop models first shipped after July 1, 1999 comply with the United States Environmental Protection Agency's Energy Star Memorandum of Understanding #3 guidelines and have autoshutdown disabled by default, with autopm enabled after 30 minutes of idleness. This is achieved by interpreting default keyword of autopm entry behavior as enabled for these machines. User is not prompted to confirm this default behavior.

To determine the version of the EPA's Energy Star Memorandum applicable to your machine, use:

prtconf -pv | grep -i energystar

Absence of a property indicates no Energy Star guidelines are applicable to your machine.

System Power Management ( suspend-resume) is currently supported only on a limited set of hardware platforms. See the Solaris Common Desktop Environment: User’s Guide for a complete list of platforms that support system Power Management. See uname(2) to programmatically determine if the machine supports suspend-resume.

SunOS 5.10 Last Revised 10 Jul 2009