The GNOME Mutter compositor has switched its KMS thread priority from a real-time value over to high priority to workaround a situation where the GNOME Shell / Mutter could crash or see its process killed.

This switch from real-time to high priority scheduling for the kernel mode-setting (KMS) thread should close a variety of bugs that have been reported over the past year. Bugs such as [1]OpenGL context loss , [2]crashes / freezes , [3]GNOME Shell killed during random actions in QEMU VMs , and a variety of other GNOME crash reports are now closed thanks to the code committed today.

[4]

Jonas Ådahl of Red Hat explains in the change-over to using a high priority KMS thread:

"In contrast to realtime scheduling, this doesn't risk us getting SIGKILL:ed when the kernel is doing busy looping in drmModeAtomicCommit() for some reason, but will according to testing, right now, give us more or less the same benefit when it comes to dispatch lateness and commit lateness."

More details on this change to fix the variety of GNOME crashes / process killed via [5]this merge request that landed in Mutter a few minutes ago.



[1] https://gitlab.gnome.org/GNOME/mutter/-/issues/3065

[2] https://gitlab.gnome.org/GNOME/mutter/-/issues/3151

[3] https://gitlab.gnome.org/GNOME/mutter/-/issues/3225

[4] https://www.phoronix.com/image-viewer.php?id=2024&image=gnome_crash_lrg

[5] https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4124