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32 .Nd "system power control utility"
50 utility monitors the system state and sets various power control options
52 It offers power-saving modes that can be
53 individually selected for operation on AC power or batteries.
54 .Bl -tag -width "hiadaptive"
56 Choose the highest performance values.
60 Choose the lowest performance values to get the most power savings.
64 Attempt to strike a balance by degrading performance when the system
65 appears idle and increasing it when the system is busy.
66 It offers a good balance between a small performance loss for greatly
67 increased power savings.
73 mode, but tuned for systems where performance and interactivity are
74 more important than power consumption.
75 It increases frequency faster, reduces frequency less aggressively, and
76 will maintain full frequency for longer.
88 recognizes these runtime options:
89 .Bl -tag -width "-r percent"
93 to use while on AC power.
97 to use while on battery power.
99 Specifies the CPU load percent level when adaptive
100 mode should begin to degrade performance to save power.
101 The default is 50% or lower.
103 Specifies the maximum frequency to throttle up to.
105 Specifies the minimum frequency to throttle down to.
107 Treat "nice" time as idle for the purpose of load calculation;
108 i.e., do not increase the CPU frequency if the CPU is only busy
109 with "nice" processes.
113 to use normally when the AC line state is unknown.
115 Specifies an alternative file in which the process ID should be stored.
117 Specifies a different polling interval (in milliseconds) for AC line state
118 and system idle levels.
119 The default is 250 ms.
121 Specifies the CPU load percent level where adaptive
122 mode should consider the CPU running and increase performance.
123 The default is 75% or higher.
125 Enforces method for AC line state refresh; by default, it is chosen
127 The set of valid methods is
134 Messages about power changes will be printed to stdout and
136 will operate in the foreground.
139 .Bl -tag -width "/var/run/powerd.pid"
140 .It Pa /var/run/powerd.pid
141 The default PID file.
150 utility first appeared in
163 added features, and wrote this manual page.
167 utility should also power down idle disks and other components besides the CPU.
173 they may override each other.
178 should probably use the
180 interface instead of polling for AC line state.