[systemd-devel] Is it meant to be possible to set IO[Read|Write]BandwidthMax on a slice ?

[Lennart Poettering]

On Do, 08.04.21 17:19, Hadrien Grasland (hadrien.grasland at ijclab.in2p3.fr) wrote:

> Le 08/04/2021 à 16:11, Lennart Poettering a écrit :
> > On Do, 08.04.21 12:24, Hadrien Grasland (hadrien.grasland at ijclab.in2p3.fr) wrote:
> >
> > > Hi everyone,
> > >
> > > In a scenario where running benchmarks on dedicated hardware is not
> > > possible, I'm trying to momentarily cap the I/O bandwidth used by
> > > interactive user sessions while benchmarks are running, in order to improve
> > > the stability of said benchmark's I/O performance.
> > Is this on cgroupsv1 or cgroupsv2?
> >
> > IIRC there was some issue that the block io controller wasn't fully
> > recursive on cgroupsv1. It should work on cgroupsv2.
>
> This is on a hybrid cgroup configuration. I (perhaps mistakenly) assumed
> that modern systemd (v246) will use the cgroups v2 hierarchy in that case,
> even though cgroups v1 is still exposed for compatibility with older apps.

No, hybrid mode means all controllers operate in cgroupsv1 mode. It's
just that the controller-less cgroupsv2 hierarchy is also mounted.

hybrid mode was a mistake, we should never have added that, it's just
a massive maintainance burden for little gain.

Lennart

--
Lennart Poettering, Berlin