How to use the command 'cpupower' (with examples)

The ‘cpupower’ command is a tool that provides options for managing CPU power and tuning. It allows users to control CPU frequency scaling, manage power-saving governors, and retrieve information about CPU cores and their available options.

Use case 1: List CPUs

Code:

sudo cpupower --cpu all info

Motivation: This command is used to retrieve information about all available CPUs in the system. It can be helpful for monitoring and troubleshooting purposes.

Explanation:

• sudo: This command requires administrative privileges to retrieve system-level information.
• cpupower: Invokes the ‘cpupower’ command.
• --cpu all: Specifies that information should be provided for all available CPUs.
• info: Instructs ‘cpupower’ to display the information.

Example output:

CPU 0:
          analyzing CPU 0:
          Intel P-state, schedutil, performance
          available cpufreq governors: performance, powersave
          hardware limits: 1.20 GHz - 3.60 GHz
          available frequency steps: 3.60 GHz, 3.50 GHz, 3.40 GHz, 3.30 GHz, 3.20 GHz, 3.10 GHz, 3.00 GHz, 2.90 GHz ...

Use case 2: Print information about all cores

Code:

sudo cpupower --cpu all info

Motivation: This command is used to retrieve detailed information about all CPU cores in the system. It can be useful for understanding the capabilities and configurations of each core.

Explanation:

• sudo: This command requires administrative privileges to retrieve system-level information.
• cpupower: Invokes the ‘cpupower’ command.
• --cpu all: Specifies that information should be provided for all available CPUs.
• info: Instructs ‘cpupower’ to display the information.

Example output:

analyzing CPU 0:
          Intel P-state, schedutil, performance
          available cpufreq governors: performance, powersave
          hardware limits: 1.20 GHz - 3.60 GHz
          available frequency steps: 3.60 GHz, 3.50 GHz, 3.40 GHz, 3.30 GHz, 3.20 GHz, 3.10 GHz, 3.00 GHz, 2.90 GHz ...

analyzing CPU 1:
          Intel P-state, schedutil, performance
          available cpufreq governors: performance, powersave
          hardware limits: 1.20 GHz - 3.60 GHz
          available frequency steps: 3.60 GHz, 3.50 GHz, 3.40 GHz, 3.30 GHz, 3.20 GHz, 3.10 GHz, 3.00 GHz, 2.90 GHz ...

Use case 3: Set all CPUs to a power-saving frequency governor

Code:

sudo cpupower --cpu all frequency-set --governor powersave

Motivation: This command is useful when you want to conserve power by setting all CPUs to a power-saving frequency governor. This can help reduce energy consumption and prolong battery life on laptops.

Explanation:

• sudo: This command requires administrative privileges to make changes to system settings.
• cpupower: Invokes the ‘cpupower’ command.
• --cpu all: Specifies that the action should be performed on all available CPUs.
• frequency-set: Instructs ‘cpupower’ to change the CPU frequency settings.
• --governor powersave: Sets the governor for all CPUs to ‘powersave’, which prioritizes power saving over performance.

Example output: No output is displayed if the command is executed successfully. The changes take effect immediately.

Use case 4: Print CPU 0’s available frequency governors

Code:

sudo cpupower --cpu 0 frequency-info g | grep "analyzing\|governors"

Motivation: This command is used to retrieve information about the available frequency governors for a specific CPU. It can be helpful for analyzing and selecting the appropriate governor based on specific requirements.

Explanation:

• sudo: This command requires administrative privileges to retrieve system-level information.
• cpupower: Invokes the ‘cpupower’ command.
• --cpu 0: Specifies that the information should be retrieved for CPU 0.
• frequency-info: Instructs ‘cpupower’ to display frequency-related information.
• g: Specifies that only the governor-related information should be displayed.
• grep "analyzing\|governors": Filters the output to include only lines containing the words “analyzing” or “governors”.

Example output:

analyzing CPU 0:
          available cpufreq governors: performance, powersave

Use case 5: Print CPU 4’s frequency from the hardware, in a human-readable format

Code:

sudo cpupower --cpu 4 frequency-info --hwfreq --human

Motivation: This command is used to retrieve the current frequency of a specific CPU (CPU 4 in this case) directly from the hardware. It provides the frequency information in a human-readable format.

Explanation:

• sudo: This command requires administrative privileges to retrieve system-level information.
• cpupower: Invokes the ‘cpupower’ command.
• --cpu 4: Specifies that the information should be retrieved for CPU 4.
• frequency-info: Instructs ‘cpupower’ to display frequency-related information.
• --hwfreq: Specifies that the frequency information should be obtained from the hardware.
• --human: Formats the output in a human-readable format.

Example output:

current CPU frequency: 2.30 GHz (asserted by BIOS)

Conclusion:

The ‘cpupower’ command is a versatile tool for managing CPU power and tuning options. It allows users to retrieve information about CPUs, set power-saving governors, and monitor frequency-related details. By using the various options and arguments provided by ‘cpupower’, users can efficiently manage CPU performance and power consumption according to their specific requirements.