linux-kernel - Re: [PATCH v2] mm: memcontrol: protect the memory in cgroup from being oom killed

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Date:   Thu, 8 Dec 2022 07:59:27 +0000
From:   程垲涛 Chengkaitao Cheng 
        <chengkaitao@...iglobal.com>
To:     Michal Hocko <mhocko@...e.com>, chengkaitao <pilgrimtao@...il.com>
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Subject: Re: [PATCH v2] mm: memcontrol: protect the memory in cgroup from
 being oom killed

At 2022-12-08 15:33:07, "Michal Hocko" <mhocko@...e.com> wrote:
>On Thu 08-12-22 11:46:44, chengkaitao wrote:
>> From: chengkaitao <pilgrimtao@...il.com>
>> 
>> We created a new interface <memory.oom.protect> for memory, If there is
>> the OOM killer under parent memory cgroup, and the memory usage of a
>> child cgroup is within its effective oom.protect boundary, the cgroup's
>> tasks won't be OOM killed unless there is no unprotected tasks in other
>> children cgroups. It draws on the logic of <memory.min/low> in the
>> inheritance relationship.
>> 
>> It has the following advantages,
>> 1. We have the ability to protect more important processes, when there
>> is a memcg's OOM killer. The oom.protect only takes effect local memcg,
>> and does not affect the OOM killer of the host.
>> 2. Historically, we can often use oom_score_adj to control a group of
>> processes, It requires that all processes in the cgroup must have a
>> common parent processes, we have to set the common parent process's
>> oom_score_adj, before it forks all children processes. So that it is
>> very difficult to apply it in other situations. Now oom.protect has no
>> such restrictions, we can protect a cgroup of processes more easily. The
>> cgroup can keep some memory, even if the OOM killer has to be called.
>> 
>> Signed-off-by: chengkaitao <pilgrimtao@...il.com>
>> ---
>> v2: Modify the formula of the process request memcg protection quota.
>
>The new formula doesn't really address concerns expressed previously.
>Please read my feedback carefully again and follow up with questions if
>something is not clear.

The previous discussion was quite scattered. Can you help me summarize
your concerns again? Let me think about the optimization plan for these
problems.
-- 
Thanks for your comment!
chengkaitao