On Wed, Mar 16, 2022 at 5:53 PM Lennart Poettering <lennart@xxxxxxxxxxxxxx> wrote:
On Mi, 16.03.22 17:30, Felip Moll (felip@xxxxxxxxxxx) wrote:
> AFAIK RemainAfterExit for services actually does cleanup the cgroup tree if
> there are no more processes in it.
It doesn't do that if delegation is on (iirc, if not I'd consider that
a bug). Same logic should apply here.
I will recheck that, but I am quite sure that on some tests I did the cgroup was cleaned up on a delegated service after the main pid terminated.
> If that behavior of keeping the cgroup tree even if there are no pids is
> what you agree with, then I coincide is a good idea to include this option
> to scopes.
Yes, that is what I was suggesting this would do.
Excellent.
> Or are you saying that I can just migrate processes wildly without
> informing systemd and just doing an 'echo > cgroup.procs' from one
> non-delegated tree to my delegated subtree?
yeah, you can do that.
Ok, so I understood that incorrectly from a former paragraph you wrote in our first e-mails. you said:
> Migrating processes wildly between cgroups is messy, because it fucks
> up accounting and is restricted permission-wise. Typically you want to
> create a cgroup and populate it, and then stick to that.
> up accounting and is restricted permission-wise. Typically you want to
> create a cgroup and populate it, and then stick to that.
There, I understood you were referring to "systemd" accounting, not "kernel" accounting.
This has been a big misunderstanding for this issue.
Note that (independently of systemd) you shouldn't migrate stuff to
aggressively, since it fucks up kernel resource accounting. i.e. it is
wise to minimize process migration in cgroups and always migrate plus
shortly after exec()
Yeah, that makes sense and I am aware of it.
I am migrating before any real work is done, exactly as you describe.
I will continue a bit more with this and inform you on what I see, but we seem to be close to a solution.
Thank you!.
