[systemd-devel] Antw: Re: Antw: [EXT] Re: Memory in systemctl status

[Benjamin Berg]

On Wed, 2020-09-30 at 11:04 +0200, Ulrich Windl wrote:
> > > > Reindl Harald <h.reindl at thelounge.net> schrieb am 30.09.2020 um 10:56 in
> Nachricht <a4f1a092-0946-d61e-f486-3fe3e2d34086 at thelounge.net>:
> 
> > Am 30.09.20 um 09:06 schrieb Ulrich Windl:
> > > > my webserver is killed because it served at monday, tuesday, thursday
> > > > and friday 4 different files with 2 GB?
> > > 
> > > cgroups is for limiting resources, not for killing processes AFAIK
> > 
> > [Service]
> > MemoryMax=4G
> > 
> > would call OOM killer
> 
> Are you sure? I thought OOM is called when the _system_ memory is exhausted.
> IMHO any memory allocation request to the process will be denied, but the
> process wouldn't be killed. But agreed, I didn't track the cgroups changes in
> the last few years.

I think you can assume that the OOM killer will kick in rather than the
allocation request being denied.

This option does cap the amount system memory that is used for the
cgroup. So if memory cannot be reclaimed (e.g. swapped out, file
backed) then the OOM killer will run within the cgroup.

As I understand it, what Reindl is looking for is seeing and limiting
the amount of resident anonymous pages that the cgroup has rather than
its real memory use.

Benjamin