illumos: manual page: power.conf.5

POWER.CONF(5) Standards, Environments, and Macros POWER.CONF(5)

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(8), to initialize the settings for Power Management. If you make
changes to this file, you must run pmconfig(8) manually for the changes
to take effect.

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 is 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 are 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 can 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 are 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 is used.

To override the default device component thresholds assigned by the Power
Management framework, a device-thresholds entry can 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 ...) ...

or

device-thresholds phys_path threshold

or

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 is 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 is printed and
the entry is 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 Suspend in 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 is 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
can be among a device's components, the device can actually be powered
down sooner than the specified threshold, but does 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 can also be defined. A device depends upon
another if none of its components might have their power levels reduced
unless all components of the other device are powered off. A dependency
can 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 is 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 can 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 as follows:

default
The behavior of the system depends upon its model. Desktop
models that fall under the United States Environmental
Protection Agency's Energy Star Memorandum of Understanding #3
have automatic device Power Management enabled, and all others
do not. See the NOTES section of this manual page for more
information.

enable
Automatic device Power Management is started when this entry
is encountered.

disable
Automatic device Power Management is stopped when this entry
is encountered.

A cpupm entry can 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 is 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 is 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.

Once every device is at its lowest possible power state, additional power
savings can be obtained by putting the system into a sleep state (if the
platform hardware is capable of doing so).

S3 Support
Because of reliability problems encountered in BIOS implementations of
X86 systems not produced by Sun Microsystems, by default, only X86
workstation products produced by Sun are considered to support S3
(suspend to RAM). To override this default, an S3-support entry (of the
format S3-support behavior) can be used to indicate if the system
supports S3.

Acceptable behavior values are:

enable
The system supports entry into S3 state. If the BIOS of a
system enabled using an S3-support enable entry does not
support entry into S3, the attempt fails and the system
returns to normal operation. If support for S3 in the BIOS of
a system enabled via an S3-support entry contains bugs, the
system can be unable to enter S3 or resume successfully, so
use this entry with caution.

disable
The system does not support entry into S3 state.

Automatic Entry Into S3
If supported by your platform, an autoS3 entry can be used to enable or
disable automatic entry into the S3 state. When in the S3 state, the
power button, keyboard and mouse activity or network traffic (depending
upon the capabilities of the platform hardware) can wake the system,
returning it to the state it was in upon entry to the S3 state. If the
platform doesn't support S3, the entry has no effect.

The format of the autoS3 entry is autoS3 behavior.

Acceptable behavior values are:

default
System behavior depends upon model. Sun X86 desktop and
workstation models that fall under the United States
Environmental Protection Agency's Energy Star Memorandum of
Understanding #3 have automatic entry into the S3 state
enabled. Non-Sun systems do not. See NOTES for more
information.

enable
Enables the system to automatically enter the S3 state if
autopm is enabled and every device is at its lowest power
state.

disable
The system does not automatically enter the S3 state.

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 is 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 can 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 can be set equal to the
start_time.

Acceptable behavior values are described as follows:

shutdown
The system is 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 is restarted automatically the next time the time
of day equals finish_time.

default
The behavior of the system depends upon its model.
Desktop models that fall under the United States
Environmental Protection Agency's Energy Star Memorandum
of Understanding #2 have automatic shutdown enabled, as
if behavior field were set to shutdown, and all others do
not. See NOTES.

unconfigured
The system does not be shut down automatically. If the
system has just been installed or upgraded, the value of
this field is 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 is
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 is 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 is
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 is
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 is executed to check for
other idleness criteria. The value of the idle time
specified in the above autoshutdown entry is 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 is 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(8) for more information.

ATTRIBUTES

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.

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.

Sun X86 desktop models first shipped after July 1, 1999 fall within
United States Environmental Protection Agency's Energy Star Memorandum of
Understanding #3 guidelines and have autopm and autoS3 enabled by
default, with entry into S3 after 30 minutes of idleness. This is
achieved by interpreting the default keyword of the autopm and autoS3
behaviors as enabled for these machines. You are not prompted to confirm
the default behavior. On all other X86 systems, the autopm and autoS3
default keywords are interpreted as disable.

June 20, 2021 POWER.CONF(5)