Instant resume on Linux: suspend to RAM, then to disk
systemd combines fast resume with zero battery drain.
- Answers
- How do you get instant resume on a Linux tablet without draining the battery?
- Topics
- Freedom · SSH · creating · design · experiment · howto · laptop · linux · minimal · tablet
- Full article on willem.com
- https://willem.com/en/2020-09-28_refining-my-tablet-os-experience/
Summary
In 2020 I configured systemd to suspend to RAM first, then after a set period to disk. Resume was near instant within that window, and beyond it the machine used no power instead of roughly 10 percent battery per hour.
Full text
A PC knows four power states: fully on, suspend to RAM, suspend to disk (hibernate) and off. Suspend to RAM resumes almost instantly but keeps consuming power, about 10 percent battery per hour on my Surface Go 2. Suspend to disk uses no power at all, but resuming is slower and full disk encryption asks for its passphrase again. Modern GNU/Linux with systemd lets you combine the two: suspend to RAM first, then automatically suspend to disk after a period you choose. I timed my bike commute and set the window to two hours, so the tablet resumes instantly between home and office and only hibernates when I stay away longer. After months of intense daily use I eventually abandoned the tablet setup as a whole.