One of the first things I did after installing the OS was to install powertop, since elementary OS itself doesn’t tune anything related to power consumption. (Hint to the elementary developers: add some sensible defaults if it is being installed on a laptop)
After enabling all the tuning options one by one, I discovered that the fan started to run as soon as I enabled the following:
|Autosuspend for USB device Touchscreen [ELAN]||echo ‘auto’ > ‘/sys/bus/usb/devices/1-9/power/control’;|
When checking the list of processes I could see a kworker process running at 100% and one more process at roughly 50%, so I went back to powerTOP and left the “Autosuspend for USB device Touchscreen [ELAN]” option disabled and rebooted into the BIOS to see if there was anything else I could tune to reduce the power consumption. Indeed, there was something to be tuned: the keyboard illumination was by default set to full intensity (which I changed to 50% intensity) and the touchscreen could be completely disabled so I disabled it since I only use the keyboard and trackpad/mouse.
Booting to elementary I again could hear the fan starting so I opened a shell and saw that once again there was a kworker process consuming 100% of one core. Apparently there is an issue related to the touch screen with the 3.19.0-43 kernel that forces you to leave the touch screen enabled in BIOS and keeps you from enabling “Autosuspend” for the device to save power.