On Thu, Aug 06, 2020 at 09:37:17PM -0700, Roman Gushchin <[email protected]> wrote: > In general, yes. But in this case I think it wouldn't be a good idea: > most often cgroups are created by a centralized daemon (systemd), > which is usually located in the root cgroup. Even if it's located not in > the root cgroup, limiting it's memory will likely affect the whole system, > even if only one specific limit was reached. The generic scheme would be (assuming the no internal process constraint, in the root too)
` root or delegated root
` manager-cgroup (systemd, docker, ...)
` [aggregation group(s)]
` job-group-1
` ...
` job-group-n
> If there is a containerized workload, which creates sub-cgroups,
> charging it's parent cgroup is perfectly effective.
No dispute about this in either approaches.
> And the opposite, if we'll charge the cgroup of a process, who created
> a cgroup, we'll not cover the most common case: systemd creating
> cgroups for all services in the system.
What I mean is that systemd should be charged for the cgroup creation.
Or more generally, any container/cgroup manager should be charged.
Consider a leak when it wouldn't remove spent cgroups, IMO the effect
(throttling, reclaim) should be exercised on such a culprit.
I don't think the existing workload (job-group-i above) should
unnecessarily suffer when only manager is acting up. Is that different
from your idea?
> Right, but it's quite unusual for tasks from one cgroup to create sub-cgroups
> in completely different cgroup. In this particular case there are tons of
> other
> ways how a task from C00 can hurt C1.
I agree with that.
If I haven't overlooked anything, this should be first case when
cgroup-related structures are accounted (please correct me).
So this is setting a precendent, if others show useful to be accounted
in the future too. I'm thinking about cpu_cgroup_css_alloc() that can
also allocate a lot (with big CPU count). The current approach would lead
situations where matching cpu and memory csses needn't to exist and that
would need special handling.
> On Thu, Aug 06, 2020 at 09:16:03PM -0700, Andrew Morton wrote:
> > These week-old issues appear to be significant. Roman? Or someone
> > else?
Despite my concerns, I don't think this is fundamental and can't be
changed later so it doesn't prevent the inclusion in 5.9 RC1.
Regards,
Michal
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