From: Yafang Shao <laoar.shao@gmail.com>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
john fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
jolsa@kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Shakeel Butt <shakeelb@google.com>,
Muchun Song <songmuchun@bytedance.com>,
Andrew Morton <akpm@linux-foundation.org>,
Zefan Li <lizefan.x@bytedance.com>,
Cgroups <cgroups@vger.kernel.org>,
netdev <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH bpf-next v3 00/13] bpf: Introduce selectable memcg for bpf map
Date: Thu, 8 Sep 2022 10:37:02 +0800 [thread overview]
Message-ID: <CALOAHbAp=g20rL0taUpQmTwymanArhO-u69Xw42s5ap39Esn=A@mail.gmail.com> (raw)
In-Reply-To: <YxkVq4S1Eoa4edjZ@P9FQF9L96D.corp.robot.car>
On Thu, Sep 8, 2022 at 6:29 AM Roman Gushchin <roman.gushchin@linux.dev> wrote:
>
> On Wed, Sep 07, 2022 at 05:43:31AM -1000, Tejun Heo wrote:
> > Hello,
> >
> > On Fri, Sep 02, 2022 at 02:29:50AM +0000, Yafang Shao wrote:
> > ...
> > > This patchset tries to resolve the above two issues by introducing a
> > > selectable memcg to limit the bpf memory. Currently we only allow to
> > > select its ancestor to avoid breaking the memcg hierarchy further.
> > > Possible use cases of the selectable memcg as follows,
> >
> > As discussed in the following thread, there are clear downsides to an
> > interface which requires the users to specify the cgroups directly.
> >
> > https://lkml.kernel.org/r/YwNold0GMOappUxc@slm.duckdns.org
> >
> > So, I don't really think this is an interface we wanna go for. I was hoping
> > to hear more from memcg folks in the above thread. Maybe ping them in that
> > thread and continue there?
>
Hi Roman,
> As I said previously, I don't like it, because it's an attempt to solve a non
> bpf-specific problem in a bpf-specific way.
>
Why do you still insist that bpf_map->memcg is not a bpf-specific
issue after so many discussions?
Do you charge the bpf-map's memory the same way as you charge the page
caches or slabs ?
No, you don't. You charge it in a bpf-specific way.
> Yes, memory cgroups are not great for accounting of shared resources, it's well
> known. This patchset looks like an attempt to "fix" it specifically for bpf maps
> in a particular cgroup setup. Honestly, I don't think it's worth the added
> complexity. Especially because a similar behaviour can be achieved simple
> by placing the task which creates the map into the desired cgroup.
Are you serious ?
Have you ever read the cgroup doc? Which clearly describe the "No
Internal Process Constraint".[1]
Obviously you can't place the task in the desired cgroup, i.e. the parent memcg.
[1] https://www.kernel.org/doc/Documentation/cgroup-v2.txt
> Beatiful? Not. Neither is the proposed solution.
>
Is it really hard to admit a fault?
--
Regards
Yafang
next prev parent reply other threads:[~2022-09-08 2:37 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-02 2:29 [PATCH bpf-next v3 00/13] bpf: Introduce selectable memcg for bpf map Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 01/13] cgroup: Update the comment on cgroup_get_from_fd Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 02/13] bpf: Introduce new helper bpf_map_put_memcg() Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 03/13] bpf: Define bpf_map_{get,put}_memcg for !CONFIG_MEMCG_KMEM Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 04/13] bpf: Call bpf_map_init_from_attr() immediately after map creation Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 05/13] bpf: Save memcg in bpf_map_init_from_attr() Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 06/13] bpf: Use scoped-based charge in bpf_map_area_alloc Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 07/13] bpf: Introduce new helpers bpf_ringbuf_pages_{alloc,free} Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 08/13] bpf: Use bpf_map_kzalloc in arraymap Yafang Shao
2022-09-02 2:29 ` [PATCH bpf-next v3 09/13] bpf: Use bpf_map_kvcalloc in bpf_local_storage Yafang Shao
2022-09-02 2:30 ` [PATCH bpf-next v3 10/13] mm, memcg: Add new helper get_obj_cgroup_from_cgroup Yafang Shao
2022-09-02 2:30 ` [PATCH bpf-next v3 11/13] mm, memcg: Add new helper task_under_memcg_hierarchy Yafang Shao
2022-09-02 2:30 ` [PATCH bpf-next v3 12/13] bpf: Add return value for bpf_map_init_from_attr Yafang Shao
2022-09-02 2:30 ` [PATCH bpf-next v3 13/13] bpf: Introduce selectable memcg for bpf map Yafang Shao
2022-09-07 15:43 ` [PATCH bpf-next v3 00/13] " Tejun Heo
2022-09-07 15:45 ` Tejun Heo
2022-09-07 16:13 ` Alexei Starovoitov
2022-09-07 16:18 ` Tejun Heo
2022-09-07 16:27 ` Alexei Starovoitov
2022-09-07 17:01 ` Tejun Heo
2022-09-08 2:44 ` Yafang Shao
2022-09-07 22:28 ` Roman Gushchin
2022-09-08 2:37 ` Yafang Shao [this message]
2022-09-08 2:43 ` Alexei Starovoitov
2022-09-08 2:48 ` Yafang Shao
2022-09-08 16:13 ` Roman Gushchin
2022-09-13 6:15 ` Yafang Shao
2022-09-16 16:53 ` Roman Gushchin
2022-09-18 3:44 ` Yafang Shao
2022-09-20 2:40 ` Roman Gushchin
2022-09-20 12:42 ` Yafang Shao
2022-09-20 23:15 ` Roman Gushchin
2022-09-21 9:36 ` Yafang Shao
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