.\"-
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.Dd August 12, 2015
.Dt COREPOWER 4
.Os
.Sh NAME
.Nm corepower
.Nd device driver for Intel Core on-die power usage estimation
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following line in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device corepower"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
corepower_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for Intel's on-die power usage estimation, that is
provided in Sandy Bridge and newer Core and Xeon CPUs, and in Atom CPUs
of the Silvermont and newer architectures.
The values are exposed through the
.Dv HW_SENSORS
.Xr sysctl 3
tree.
For example:
.Bd -literal -offset indent
% sysctl hw.sensors
hw.sensors.cpu_node0.power0: 0.84 W (node0 Package Power)
hw.sensors.cpu_node0.power1: 0.73 W (node0 DRAM Power)
hw.sensors.cpu_node0.power2: 0.02 W (node0 Cores Power)
hw.sensors.cpu_node0.power3: 0.00 W (node0 Graphics Power)
.Ed
.Pp
Both the
.Dq Cores Power
and the
.Dq Graphics Power
values are included in the
.Dq Package Power
value, which estimates the total power usage of the CPU package.
.Sh SEE ALSO
.Xr systat 1 ,
.Xr sysctl 3 ,
.Xr devctl 4 ,
.Xr devd 8 ,
.Xr sensorsd 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Dx 4.3 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Imre Vadasz Aq Mt imre@vdsz.com .
.Sh BUGS
For some Xeon and Core-i CPUs this driver might incorrectly assume that the
MSR_PP1_ENERGY_STATUS MSR for measuring power usage of the integrated GPU is
available.