System information

Power Management 147
11.4.1 Tuning Options for P-States
The CPUfreq subsystem offers several tuning options for P-states: You can switch be-
tween the different governors, influence minimum or maximum CPU frequency to be
used or change individual governor parameters.
To switch to another governor at runtime, use cpupowerfrequency-set (or
cpufreq-set) with the -g option. For example, running the following command
(as root) will activate the on-demand governor:
cpupower frequency-set -g ondemand
If you want the change in governor to persist also after a reboot or shutdown, use the
pm-profiler as described in Section11.5, “Creating and Using Power Management
Profiles” (page149).
To set values for the minimum or maximum CPU frequency the governor may select,
use the -d or -u option, respectively.
Apart from the governor settings that can be influenced with cpupower or
cpufreq*, you can also tune further governor parameters manually, for example,
Ignoring Nice Values in Processor Utilization (page147).
Procedure11.1: Ignoring Nice Values in Processor Utilization
One parameter you might want to change for the on-demand or conservative governor
is ignore_nice_load.
Each process has a niceness value associated with it. This value is used by the kernel
to determine which processes require more processor time than others. The higher
the nice value, the lower the priority of the process. Or: the “nicer” a process, the less
CPU it will try to take from other processes.
If the ignore_nice_load parameter for the on-demand or conservative gover-
nor is set to 1, any processes with a nice value will not be counted toward the over-
all processor utilization. When ignore_nice_load is set to 0 (default value), all
processes are counted toward the utilization. Adjusting this parameter can be useful
if you are running something that requires a lot of processor capacity but you do not
care about the runtime.
1 Change to the subdirectory of the governor whose settings you want to modify, for
example: