Powertop

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Revision as of 22:34, 22 May 2014 by Siosm (Talk | contribs) (Suggest udev rules, module parameters and sysctl as recommended settings versus PowerTOP auto-tune)

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PowerTOP is a tool provided by Intel to enable various powersaving modes in userspace, kernel and hardware. It is possible to monitor processes and show which of them are utilizing the CPU and wake it from its Idle-States.

Installation

Install package powertop, available in official repositories.

PowerTOP features are detailed on the release notes for each version on the PowerTOP blog.

Tips and tricks

PowerTOP suggests a few methods to reduce the power consumption further. However, in the console, PowerTOP does not display the parameters. To find out which ones are suggested, proceed as follows:

  1. If you have changed parameters (e.g. in PowerTOP), reboot so that the system has default state of the parameters.
  2. Use PowerTOP to produce a report on parameters: # powertop --html=powerreport.html
  3. Open this report in your favorite web browser. The "Tuning" tab of the report now shows the actual parameters suggested by the tool to apply to save power.
  4. They are two ways to apply those settings:
    • Recommended: You can apply these settings at boot by using module parameters, udev rules and sysctl. For details, see the power saving page.
    • You can use the --auto-tune feature from PowerTOP which sets all tunable options to their GOOD setting. This can be combined with systemd to have the tunables set on boot.
/etc/systemd/system/powertop.service
[Unit]
Description=Powertop tunings

[Service]
Type=oneshot
RemainAfterExit=no
ExecStart=/usr/bin/powertop --auto-tune
# "powertop --auto-tune" still needs a terminal for some reason. Possibly a bug?
Environment="TERM=xterm"

[Install]
WantedBy=multi-user.target

Troubleshooting

Error: Cannot load from file

If you get an error like the following when starting powertop, you are likely to have powertop not allowed collecting enough measurement data yet. All you need to do is to keep powertop running for a certain time whilst being on battery.

Loaded 39 prior measurements
Cannot load from file /var/cache/powertop/saved_parameters.powertop
Cannot load from file /var/cache/powertop/saved_parameters.powertop

Calibration to prevent inaccurate measurement

If you experience inaccurate measurement, then it is likely that you need to calibrate powertop first. This can be done by running powertop with the --calibrate parameter.

# powertop --calibrate

See also