Package: linux-image-amd64
Version: 6.6.15-2
Debian testing/trixie, kernel 6.6.15-2 (2024-02-04)
xfce
Case 1:
Start a command that runs for a long time, say `ffmpeg`. switch to other programs, i.e. web browser or other terminal windows, and keep using the computer. After a while, ffmpeg cpu usage drops to 0%, switch back to ffmpeg's terminal window, it will go back to running.
Case 2:
start ffmpeg, leave the computer untouched, then screensaver runs, then the display turns off. No suspend, no hibernate, no shutdown. after a while, wake up display, unlock session, ffmpeg is using 0% CPU. switch back to its terminal window, it resumes.
I am not sure which package is causing this. This happened long before 6.6.15 kernels.