{"id":175,"date":"2017-01-09T12:24:23","date_gmt":"2017-01-09T12:24:23","guid":{"rendered":"http:\/\/info.ffteixeira.net\/2017\/01\/09\/linux-laptop-power-tuning-with-powertop\/"},"modified":"2017-01-09T12:24:23","modified_gmt":"2017-01-09T12:24:23","slug":"linux-laptop-power-tuning-with-powertop","status":"publish","type":"post","link":"https:\/\/blog.ffteixeira.net\/?p=175","title":{"rendered":"Linux Laptop Power Tuning with Powertop"},"content":{"rendered":"

There’s an easy way to reduce power usage on Linux laptops using Intel’s Powertop<\/a> utility.<\/p>\n

Powertop polls your existing power usage and recommends tunings for your hardware. I’ll show you how to quickly make the most of your battery life using this tool as well as tuned and cpufreq.<\/p>\n

 <\/p>\n

Install Powertop<\/strong><\/span>
I’m using Fedora for these examples, but most distributions will have this available – adjust as needed.<\/p>\n

\ndnf install powertop -y<\/pre>\n
Note Normal Pre-tune Power Usage<\/strong><\/span>
Run powertop to see normal power usage, make sure you are not connected<\/strong> to a power source.<\/p>\n
\npowertop<\/pre>\n
\"powertop-manual\"<\/a><\/p>\n
Poll Usage and Record<\/strong><\/span>
Next you’ll want to run powertop with the –calibrate and –html flag while not connected<\/strong> to a power source. Note that –calibrate will disconnect you<\/strong> from wifi temporarily and you might see some screen flickering.<\/p>\n
\npowertop --calibrate<\/pre>\n
\npowertop --html<\/pre>\n
You’ll see some output like below, when it’s completed you’ll have a powertop.html<\/em> file wherever you ran the program.<\/p>\n
\nLoaded 750 prior measurements\n RAPL device for cpu 0\n RAPL Using PowerCap Sysfs : Domain Mask f\n RAPL device for cpu 0\n RAPL Using PowerCap Sysfs : Domain Mask f\n RAPL device for cpu 0\n RAPL Using PowerCap Sysfs : Domain Mask f\n Devfreq not enabled\n Preparing to take measurements\n unknown op '{'\n Taking 1 measurement(s) for a duration of 20 second(s) each.\n PowerTOP outputing using base filename powertop.html<\/pre>\n
Output and Recommendations<\/strong><\/span>
Point a browser to the powertop.html file and you’ll see things like status, power usage, processes using the most power and lastly tuning. The tuning tab is what we’ll focus on.<\/p>\n
\"powertop\"<\/a><\/p>\n
\"powertop-untuned\"<\/a><\/p>\n
Apply Tuning Recommendations<\/strong><\/span>
There’s several options you can pursue here. You can either manually copy\/paste the tuning recommendations from the generated HTML tunings above or you can use lynx and a bit of sed to spit them out and apply them all. Lastly, you can just set powertop to use the –auto-tune feature (though you’ll need to run it at boot everytime). It’s best to review them all prior.<\/p>\n
Note:<\/strong> you might want to forgo any USB suspend options if you use an external keyboard or mouse as USB is always slow to resume and this causes issues for some people.<\/em><\/p>\n
Option #1 – Apply Tuning Recommendations Permanently<\/strong><\/p>\n
In this example I’ll show all tunings in an easy, copy\/paste fashion to make the most of your time.<\/p>\n
Convert HTML to TXT<\/span><\/p>\n
\nlynx -dump -width 200 powertop.html > powertop.txt<\/pre>\n
Strip out Recommended Power Tunings<\/span><\/p>\n
\ncat powertop.txt | sed 's\/^.*echo\/echo\/' | \\\nsed 's\/^.*ethtool\/ethtool\/' | egrep -B3 "echo|ethtool|hdparm" \\\n| egrep -v "Software|Description|Script" > \/tmp\/tuning.txt<\/pre>\n
Now review what’s been captured, you can paste these them all to apply them or choose individually as you prefer.<\/p>\n
\ncat \/tmp\/tuning.txt | less<\/pre>\n
Note the tuning recommendations..<\/p>\n
\necho '1500' > '\/proc\/sys\/vm\/dirty_writeback_centisecs';\necho '1' > '\/sys\/module\/snd_hda_intel\/parameters\/power_save';\necho '0' > '\/proc\/sys\/kernel\/nmi_watchdog';\necho 'auto' > '\/sys\/bus\/i2c\/devices\/i2c-3\/device\/power\/control';\necho 'auto' > '\/sys\/bus\/i2c\/devices\/i2c-4\/device\/power\/control';\necho 'auto' > '\/sys\/bus\/i2c\/devices\/i2c-1\/device\/power\/control';\necho 'auto' > '\/sys\/bus\/i2c\/devices\/i2c-2\/device\/power\/control';\necho 'auto' > '\/sys\/bus\/i2c\/devices\/i2c-0\/device\/power\/control';\necho 'auto' > '\/sys\/bus\/usb\/devices\/8-1\/power\/control';\necho 'auto' > '\/sys\/bus\/usb\/devices\/3-2\/power\/control';\n-- snip --<\/pre>\n
Review<\/strong> the tunings.
If you like how this looks, you can also make a script to apply it all instead of pasting it.<\/p>\n
\necho '#!\/bin\/bash' > \/tmp\/tuning.sh\ncat powertop.txt | sed 's\/^.*echo\/echo\/' | sed \\\n's\/^.*ethtool\/ethtool\/' | egrep -B3 "echo|ethtool|hdparm" \\\n| egrep -v "Software|Description|Script" >> \/tmp\/tuning.sh<\/pre>\n
Run the Script<\/span><\/p>\n
\nchmod +x \/tmp\/tuning.sh\nsh \/tmp\/tuning.sh<\/pre>\n
Option #2 – Auto Tune<\/strong>
Powertop provides the option to simply apply all the recommended settings for you, but they will be lost on boot.<\/p>\n
\npowertop --auto-tune<\/pre>\n
Persist after boot<\/strong>
You can use the following systemd unit file to simply make powertop a systemd-controlled service<\/p>\n
\ncat > \/etc\/systemd\/system\/powertop.service << EOF\n[Unit]\nDescription=Powertop tunings\n\n[Service]\nType=idle\nExecStart=\/usr\/bin\/powertop --auto-tune\n\n[Install]\nWantedBy=multi-user.target\nEOF<\/pre>\n
\nsystemctl enable powertop<\/pre>\n
Running Powertop<\/strong><\/span>
You can run powertop manually at any time to get a feeling for your battery usage. It might be a good idea to see before\/after improvement. For comparison I get an average of 6 to 8W of power usage under a normal workload on my Lenovo x240 running Fedora 22 on Kernel 4.2.7. I believe I average around 6-9W, down from 10-12W with no tuning – quite an improvement!<\/p>\n
\"battery-best-10hr\"<\/a><\/p>\n
Tuned: Further Savings<\/strong><\/span>
You can also use a tuned profile to provide additional power management savings.<\/p>\n
Install tuned and Profiles<\/span><\/p>\n
\ndnf install tuned-profiles-compat tuned -y<\/pre>\n
Enable Tuned and Set Profile<\/span><\/p>\n
\nsystemctl enable tuned.service\nsystemctl start tuned.service\ntuned-adm profile laptop-battery-powersave<\/pre>\n
You can list other profiles available and see what works best, just “powersave” is good too.<\/p>\n
\ntuned-adm list<\/pre>\n
Alternative to tuned profiles<\/span> – there is also a command called powertop2tuned<\/em> that will generate a tuned profile based directly on your powertop –html output, you can specify an existing html file or run it without options and it will create one. I just use the laptop-battery-powersave<\/em> tuned profile instead. Below is an example where powertop-settings is the new tuned profile you’d want to use.<\/p>\n
\npowertop2tuned powertop-settings<\/pre>\n
\nRunning PowerTOP, please wait...\nGenerating shell script \/etc\/tuned\/powertop-settings\/script.sh\nGenerating Tuned config file \/etc\/tuned\/powertop-settings\/tuned.conf<\/pre>\n
Now apply the tuned profile based on powertop settings, you’d use what you named it above.
More info can be found here.<\/a><\/p>\n
\ntuned-adm profile powertop-settings<\/pre>\n
Cpufreq – Further Tuning<\/strong><\/span>
Lastly, you will want to enable cpufreq so you can have CPU frequency scale up and down based on demand – this will save a noticable amount of power basd on the powersave<\/em> profile.<\/p>\n
Install cpufreq-utils<\/span><\/p>\n
\ndnf install cpufreq-utils -y<\/pre>\n
Use Powersave Options<\/span><\/p>\n
\ncpupower frequency-set -g powersave<\/pre>\n
Check your settings<\/span><\/p>\n
\ncpupower frequency-info<\/pre>\n
\nanalyzing CPU 0:\n  driver: intel_pstate\n  CPUs which run at the same hardware frequency: 0\n  CPUs which need to have their frequency set by software: 0\n  maximum transition latency: 0.97 ms.\n  hardware limits: 800 MHz - 3.30 GHz\n  available cpufreq governors: performance, powersave\n  current policy: frequency should be within 800 MHz and 3.30 GHz.\n                  The governor "powersave" may decide speed to use\n                  within this range.\n  current CPU frequency is 800 MHz (asserted by call to hardware).\n  boost state support:\n    Supported: yes\n    Active: yes<\/pre>\n
Kernel GPU Savings Options (NOTE<\/span> i915 chipset only<\/em>)<\/strong><\/span>
I also use the following kernel options for my laptop, a Lenovo x240 using the Intel i915<\/strong> chipset. These settings won’t work for everyone so research them before applying. If you’re not sure skip over this part.<\/p>\n