Change the default suspend variant from s2idle to deep where the system supports suspend-to-RAM.
The Problem
Laptop drains a lot of battery when in sleep mode after upgrade to Ubuntu 24.04.
System logs:
systemd-sleep[]: Performing sleep operation 'suspend'... kernel: PM: suspend entry (s2idle)
OS version:
$ lsb_release -a Distributor ID: Ubuntu Description: Ubuntu 24.04.2 LTS Release: 24.04 Codename: noble
Kernel version:
$ uname -r 6.11.0-17-generic
Sleep configuration:
$ cat /sys/power/mem_sleep [s2idle] deep
The Solution
Instead of s2idle suspend-to-idle, use deep which means suspend-to-RAM.
Run the following command to set deep sleep mode:
$ echo deep | sudo tee /sys/power/mem_sleep
Create a cron job to set the parameter automatically:
$ echo '#!/bin/bash' | sudo tee /etc/cron.hourly/mem_sleep $ echo 'echo deep > /sys/power/mem_sleep' | sudo tee -a /etc/cron.hourly/mem_sleep
Verify:
$ cat /sys/power/mem_sleep s2idle [deep]
Attempt to suspend the system and then verify its logs:
systemd-sleep[]: Performing sleep operation 'suspend'... kernel: PM: suspend entry (deep)
References
https://www.kernel.org/doc/html/latest/admin-guide/pm/sleep-states.html