From: Andrew Morton <akpm@linux-foundation.org>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Roman Gushchin <guro@fb.com>, Dennis Zhou <dennis@kernel.org>,
Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Shakeel Butt <shakeelb@google.com>,
linux-mm@kvack.org, kernel-team@fb.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 4/5] mm: memcg: charge memcg percpu memory to the parent cgroup
Date: Thu, 6 Aug 2020 21:16:03 -0700 [thread overview]
Message-ID: <20200806211603.195727c03995c3a25ffc6d76@linux-foundation.org> (raw)
In-Reply-To: <20200729171039.GA22229@blackbody.suse.cz>
On Wed, 29 Jul 2020 19:10:39 +0200 Michal Koutný <mkoutny@suse.com> wrote:
> Hello.
>
> On Tue, Jun 23, 2020 at 11:45:14AM -0700, Roman Gushchin <guro@fb.com> wrote:
> > Because the size of memory cgroup internal structures can dramatically
> > exceed the size of object or page which is pinning it in the memory, it's
> > not a good idea to simple ignore it. It actually breaks the isolation
> > between cgroups.
> No doubt about accounting the memory if it's significant amount.
>
> > Let's account the consumed percpu memory to the parent cgroup.
> Why did you choose charging to the parent of the created cgroup?
>
> Should the charge go the cgroup _that is creating_ the new memcg?
>
> One reason is that there are the throttling mechanisms for memory limits
> and those are better exercised when the actor and its memory artefact
> are the same cgroup, aren't they?
>
> The second reason is based on the example Dlegation Containment
> (Documentation/admin-guide/cgroup-v2.rst)
>
> > For an example, let's assume cgroups C0 and C1 have been delegated to
> > user U0 who created C00, C01 under C0 and C10 under C1 as follows and
> > all processes under C0 and C1 belong to U0::
> >
> > ~~~~~~~~~~~~~ - C0 - C00
> > ~ cgroup ~ \ C01
> > ~ hierarchy ~
> > ~~~~~~~~~~~~~ - C1 - C10
>
> Thanks to permissions a task running in C0 creating a cgroup in C1 would
> deplete C1's supply victimizing tasks inside C1.
These week-old issues appear to be significant. Roman? Or someone
else?
next prev parent reply other threads:[~2020-08-07 4:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 18:45 [PATCH v3 0/5] mm: memcg accounting of percpu memory Roman Gushchin
2020-06-23 18:45 ` [PATCH v3 1/5] percpu: return number of released bytes from pcpu_free_area() Roman Gushchin
2020-06-24 0:58 ` Shakeel Butt
2020-06-23 18:45 ` [PATCH v3 2/5] mm: memcg/percpu: account percpu memory to memory cgroups Roman Gushchin
2020-06-24 1:25 ` Shakeel Butt
2020-06-23 18:45 ` [PATCH v3 3/5] mm: memcg/percpu: per-memcg percpu memory statistics Roman Gushchin
2020-06-24 1:35 ` Shakeel Butt
2020-08-11 15:05 ` Johannes Weiner
2020-06-23 18:45 ` [PATCH v3 4/5] mm: memcg: charge memcg percpu memory to the parent cgroup Roman Gushchin
2020-06-24 1:40 ` Shakeel Butt
2020-06-24 1:49 ` Roman Gushchin
2020-07-29 17:10 ` Michal Koutný
2020-08-07 4:16 ` Andrew Morton [this message]
2020-08-07 4:37 ` Roman Gushchin
2020-08-10 19:33 ` Roman Gushchin
2020-08-11 14:47 ` Michal Koutný
2020-08-11 16:55 ` Roman Gushchin
2020-08-11 18:32 ` Michal Koutný
2020-08-11 19:32 ` Roman Gushchin
2020-08-12 16:28 ` Michal Koutný
2020-08-11 15:27 ` Johannes Weiner
2020-08-11 17:06 ` Roman Gushchin
2020-08-13 9:16 ` Naresh Kamboju
2020-08-13 23:27 ` Stephen Rothwell
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