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30 .Nd "system power control utility"
48 utility monitors the system state and sets various power control options
50 It offers power-saving modes that can be
51 individually selected for operation on AC power or batteries.
52 .Bl -tag -width "hiadaptive"
54 Choose the highest performance values.
58 Choose the lowest performance values to get the most power savings.
62 Attempt to strike a balance by degrading performance when the system
63 appears idle and increasing it when the system is busy.
64 It offers a good balance between a small performance loss for greatly
65 increased power savings.
71 mode, but tuned for systems where performance and interactivity are
72 more important than power consumption.
73 It increases frequency faster, reduces frequency less aggressively, and
74 will maintain full frequency for longer.
86 recognizes these runtime options:
87 .Bl -tag -width "-r percent"
91 to use while on AC power.
95 to use while on battery power.
97 Specifies the CPU load percent level when adaptive
98 mode should begin to degrade performance to save power.
99 The default is 50% or lower.
101 Specifies the maximum frequency to throttle up to.
103 Specifies the minimum frequency to throttle down to.
105 Treat "nice" time as idle for the purpose of load calculation;
106 i.e., do not increase the CPU frequency if the CPU is only busy
107 with "nice" processes.
111 to use normally when the AC line state is unknown.
113 Specifies an alternative file in which the process ID should be stored.
115 Specifies a different polling interval (in milliseconds) for AC line state
116 and system idle levels.
117 The default is 250 ms.
119 Specifies the CPU load percent level where adaptive
120 mode should consider the CPU running and increase performance.
121 The default is 75% or higher.
123 Enforces method for AC line state refresh; by default, it is chosen
125 The set of valid methods is
132 Messages about power changes will be printed to stdout and
134 will operate in the foreground.
137 .Bl -tag -width "/var/run/powerd.pid"
138 .It Pa /var/run/powerd.pid
139 The default PID file.
149 utility first appeared in
162 added features, and wrote this manual page.
166 utility should also power down idle disks and other components besides the CPU.
171 .Pa /etc/rc.d/power_profile ,
172 they may override each other.
177 should probably use the
179 interface instead of polling for AC line state.