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From:   Yafang Shao <laoar.shao@gmail.com>
Date:   Thu, 9 Jul 2020 15:41:11 +0800
Message-ID: <CALOAHbAezHHN58cn0unLNbOjHJyYW=zhzQxpQD8_rD4O7qmYRQ@mail.gmail.com>
Subject: Re: [PATCH 2/2] doc, mm: clarify /proc/<pid>/oom_score value range
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Michal Hocko <mhocko@suse.com>
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On Thu, Jul 9, 2020 at 2:26 PM Michal Hocko <mhocko@kernel.org> wrote:
>
> From: Michal Hocko <mhocko@suse.com>
>
> The exported value includes oom_score_adj so the range is no [0, 1000]
> as described in the previous section but rather [0, 2000]. Mention that
> fact explicitly.
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  Documentation/filesystems/proc.rst | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
> index 8e3b5dffcfa8..78a0dec323a3 100644
> --- a/Documentation/filesystems/proc.rst
> +++ b/Documentation/filesystems/proc.rst
> @@ -1673,6 +1673,9 @@ requires CAP_SYS_RESOURCE.
>  3.2 /proc/<pid>/oom_score - Display current oom-killer score
>  -------------------------------------------------------------
>
> +Please note that the exported value includes oom_score_adj so it is effectively
> +in range [0,2000].
> +

[0, 2000] may be not a proper range, see my reply in another thread.[1]
As this value hasn't been documented before and nobody notices that, I
think there might be no user really care about it before.
So we should discuss the proper range if we really think the user will
care about this value.

[1]. https://lore.kernel.org/linux-mm/CALOAHbAvj-gWZMLef=PuKTfDScwfM8gPPX0evzjoref1bG=zwA@mail.gmail.com/T/#m2332c3e6b7f869383cb74ab3a0f7b6c670b3b23b

>  This file can be used to check the current score used by the oom-killer is for
>  any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
>  process should be killed in an out-of-memory situation.
> --
> 2.27.0
>


-- 
Thanks
Yafang