System information
142 System Analysis and Tuning Guide
cpupower -c 4 frequency-info (versus cpufreq-info -c 4)
cpupower lets you also specify a list of CPUs with -c. For example, the follow-
ing command would affect the CPUs 1 , 2, 3, and 5:
cpupower -c 1-3,5 frequency-set
• If cpufreq* and cpupower are used without the -c option, the behavior dif-
fers:
cpufreq-set automatically applies the command to CPU 0, whereas cpupow-
erfrequency-set applies the command to all CPUs in this case. Typically,
cpupower *info subcommands access only CPU 0, whereas cpufreq-info
accesses all CPUs, if not specified otherwise.
11.3.2.1 Viewing Current Settings with cpupower
Similar to cpufreq-info, cpupowerfrequency-info also shows the sta-
tistics of the cpufreq driver used in the Kernel. Additionally, it shows if turbo (boost)
states are supported and enabled in the BIOS. Run without any options, it shows an
output similar to the following:
Example11.2: Example Output of cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1 2 3
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 2.00 GHz - 2.83 GHz
available frequency steps: 2.83 GHz, 2.34 GHz, 2.00 GHz
available cpufreq governors: conservative, userspace, powersave, ondemand, performance
current policy: frequency should be within 2.00 GHz and 2.83 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 2.00 GHz (asserted by call to hardware).
boost state support:
Supported: yes
Active: yes
To get the current values for all CPUs, use cpupower-callfrequen-
cy-info.