Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
POWERD(8)               FreeBSD System Manager's Manual              POWERD(8)

     powerd - system power control utility

     powerd [-a mode] [-b mode] [-i percent] [-n mode] [-p ival] [-P pidfile]
            [-r percent] [-v]

     The powerd utility monitors the system state and sets various power
     control options accordingly.  It offers three modes (maximum, minimum,
     and adaptive) that can be individually selected while on AC power or

     Maximum mode chooses the highest performance values.  Minimum mode
     selects the lowest performance values to get the most power savings.
     Adaptive mode attempts to strike a balance by degrading performance when
     the system appears idle and increasing it when the system is busy.  It
     offers a good balance between a small performance loss for greatly
     increased power savings.  The default mode is adaptive.

     The powerd utility recognizes the following runtime options:

     -a mode           Selects the mode to use while on AC power.

     -b mode           Selects the mode to use while on battery power.

     -i percent        Specifies the CPU idle percent level when adaptive mode
                       should begin to degrade performance to save power.  The
                       default is 90% or higher.

     -n mode           Selects the mode to use normally when the AC line state
                       is unknown.

     -p ival           Specifies a different polling interval (in
                       milliseconds) for AC line state and system idle levels.
                       The default is 500 ms.

     -P                Specify an alternative file in which to store the
                       process ID.  The default is /var/run/

     -r percent        Specifies the CPU idle percent level where adaptive
                       mode should consider the CPU running and increase
                       performance.  The default is 65% or lower.

     -v                Verbose mode.  Messages about power changes will be
                       printed to stdout and powerd will operate in the

     acpi(4), apm(4), cpufreq(4)

     The powerd utility first appeared in FreeBSD 6.0.

     Colin Percival first wrote estctrl, the utility that powerd is based on.
     Nate Lawson then updated it for cpufreq(4), added features, and wrote
     this manual page.

     The powerd utility should also power down idle disks and other components
     besides the CPU.

     If powerd is used with power_profile, they may override each other.

     The powerd utility should probably use the devctl(4) interface instead of
     polling for AC line state.

FreeBSD 11.0-PRERELEASE         April 10, 2005         FreeBSD 11.0-PRERELEASE


Want to link to this manual page? Use this URL:

home | help