Linux 4.1 Power Consumption Appears To Improve For Intel Users

A Red Hat developer mentioned to us at Phoronix that they're seeing "drastically improved battery life" in some cases with the Linux 4.1 kernel to the extent that it's up to 2~4 hours of extra battery life with the kernel upgrade to Git. I've since started some fresh Linux laptop battery tests.

The initial belief is that the power-savings for Linux 4.1 are coming courtesy of improvements to the Intel drivers. There are many Linux 4.1 changes, including a variety of refinements to the Intel DRM driver, P-State changes to Intel Bay Trail / Cherry Trail hardware, etc.

Unfortunately I don't have enough extra USB-interfacing AC power meters to be monitoring the power consumption on a daily basis via my daily benchmarks of the Linux kernel but since being tipped off to the Intel Linux power improvements being seen in Linux 4.1, I've started carrying out some tests using the usual Phoronix Test Suite for open-source, automated Linux benchmarking. Being tested are laptops on a battery charge and then desktops using the WattsUp power meter.

I'll have more results to share shortly, but for ending out the weekend, here's some results from an ASUS Zenbook UX301LAA with an Intel Core i7 Haswell CPU and Iris Graphics. Compared were Linux 3.19, 4.0, and 4.1 Git from today using the same Ubuntu installation and all other settings. The results already indicate some interesting changes as shown on the next pages.