NAME

cpuspeed - Plugin to monitor CPU speed

APPLICABLE SYSTEMS

Linux systems with a working CPU speed governor/stats kernel module that can be accessed through the /sys filesystem.

CONFIGURATION

None needed by default.

You can set one environment variable to modify the plugins behaviour:

  [cpuspeed]
     env.scaleto100 yes

Show the frequency as a percentage instead of absolute frequency. If set the "yes" the plugin sets up a CDEF to change the speed in Hz to percent.

If you set or unset this the whole time series will be shown in the same way, either as Hz or percent (as the graphs are updated).

INTERPRETATION

The plugin supports two sources of information.

The optimal source of information is the "acpi-cpufreq" kernel module. It provides access to the accumulated time a CPU spent in a specific speed state (see /sys/devices/system/cpu/*/cpufreq/stats/time_in_state). This value is fine-grained and represents the *average* CPU speed for every data collection period. This data is available only for non-Intel CPUs.

An alternative (sub-optimal) source of information is provided by the "intel_pstate" driver (typically built into a kernel). This driver delivers only *instant* information about the CPU speed (at the time of the munin data collection). This is not necessarily representative for the real CPU speed history. The "pstate" driver conflicts with "acpi-cpufreq". Thus hosts with an Intel CPU are usually stuck with "intel_pstate" as a less optimal source of frequency information.

BUGS

Nah.

AUTHOR

Nicolai Langfeldt

LICENSE

GPLv2

MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf