Earlyoom maintainer here. I think it's too early to switch to
systemd-oomd, because it was just merged to the systemd codebase and is
still an experimental feature.
Hi! I authored the PR for systemd-oomd. It was merged as a feature for "preview"
rather than "release", but that was so the interface could be improved based on
feedback. The feature itself was tested against a subset of Facebook's servers and it
behaves the same as the stand alone oomd that we've been running for years (minus the
knobs that were not implemented in systemd-oomd).
In earlyoom we have a list of processes that cannot be killed (eg.
dnf/packagekit/etc.), so it is absolutely safe to use as a default
userspace OOM solution. We currently don't know anything about the
systemd-oomd safety for regular use on end user desktops. We can't even
test it on the current stable Fedora release.
PSI takes into account cgroup memory protections so you can bias away from cgroups with
critical apps by setting MemoryLow= to the appropriate values to prevent reclaim.
That's why I think this change need to be postponed to Fedora 35
(opt-in
in F34 and default in F35).
I'm actually not opposed to that.