linux-kernel - Re: [PATCH] mm/ksm: delete the redundant ksm_merging

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Message-Id: <20230628031233.9734-1-xu.xin16@zte.com.cn>
Date:   Wed, 28 Jun 2023 11:12:33 +0800
From:   xu xin <xu.xin.sc@...il.com>
To:     sunnanyong@...wei.com
Cc:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, wangkefeng.wang@...wei.com,
        yang.yang29@....com.cn, xu.xin16@....com.cn
Subject: Re: [PATCH] mm/ksm: delete the redundant ksm_merging_pages interafce in proc

> Message-ID: <20230627133542.2446285-1-sunnanyong@...wei.com> (raw)
> 
> Since the ksm_merging_pages information already included in
> /proc/<pid>/ksm_stat, we can delete /proc/<pid>/ksm_merging_pages to
> make the directory more clean, and can save a little bit resources.

I think it's ok to remove it because this interface was not proposed for a long time.
I believe its users are not many yet. The earlier we delete it, the better.

The patch is good except some grammar issues.

Reviewed-by: xu xin <xu.xin16@....com.cn>

> /proc/<pid>/ksm_stat, we can delete /proc/<pid>/ksm_merging_pages to
> make the directory more clean, and can save a little bit resources.
> 
> Signed-off-by: Nanyong Sun <sunnanyong@...wei.com>
> ---
>  Documentation/admin-guide/mm/ksm.rst              |  6 +++---
>  .../translations/zh_CN/admin-guide/mm/ksm.rst     |  4 ++--
>  fs/proc/base.c                                    | 15 ---------------
>  3 files changed, 5 insertions(+), 20 deletions(-)
> 
> diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
> index 7626392fe82c..e668d4b5e800 100644
> --- a/Documentation/admin-guide/mm/ksm.rst
> +++ b/Documentation/admin-guide/mm/ksm.rst
> @@ -208,9 +208,9 @@ several times, which are unprofitable memory consumed.
>  	process_profit =~ ksm_merging_pages * sizeof(page) -
>  			  ksm_rmap_items * sizeof(rmap_item).
>  
> -   where ksm_merging_pages is shown under the directory ``/proc/<pid>/``,
> -   and ksm_rmap_items is shown in ``/proc/<pid>/ksm_stat``. The process profit
> -   is also shown in ``/proc/<pid>/ksm_stat`` as ksm_process_profit.
> +   where ksm_merging_pages and ksm_rmap_items is shown in the file

 is -> are

> +   ``/proc/<pid>/ksm_stat``. The process profit is also shown in
> +   ``/proc/<pid>/ksm_stat`` as ksm_process_profit.
>  
>  From the perspective of application, a high ratio of ``ksm_rmap_items`` to
>  ``ksm_merging_pages`` means a bad madvise-applied policy, so developers or
> diff --git a/Documentation/translations/zh_CN/admin-guide/mm/ksm.rst b/Documentation/translations/zh_CN/admin-guide/mm/ksm.rst
> index 0029c4fd2201..1662f271efc8 100644
> --- a/Documentation/translations/zh_CN/admin-guide/mm/ksm.rst
> +++ b/Documentation/translations/zh_CN/admin-guide/mm/ksm.rst
> @@ -167,8 +167,8 @@ KSM可以通过合并相同的页面来节省内存，但也会消耗额外的
>         process_profit =~ ksm_merging_pages * sizeof(page) -
>                           ksm_rmap_items * sizeof(rmap_item).
>  
> -   其中ksm_merging_pages显示在 ``/proc/<pid>/`` 目录下，而ksm_rmap_items
> -   显示在 ``/proc/<pid>/ksm_stat`` 。
> +   其中ksm_merging_pages、ksm_rmap_items显示在 ``/proc/<pid>/ksm_stat`` 文件中，收益
> +   值ksm_process_profit也显示在该文件中。
>  
>  从应用的角度来看， ``ksm_rmap_items`` 和 ``ksm_merging_pages`` 的高比例意
>  味着不好的madvise-applied策略，所以开发者或管理员必须重新考虑如何改变madvis策
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 05452c3b9872..173261dbeaea 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -3186,19 +3186,6 @@ static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns,
>  #endif /* CONFIG_LIVEPATCH */
>  
>  #ifdef CONFIG_KSM
> -static int proc_pid_ksm_merging_pages(struct seq_file *m, struct pid_namespace *ns,
> -				struct pid *pid, struct task_struct *task)
> -{
> -	struct mm_struct *mm;
> -
> -	mm = get_task_mm(task);
> -	if (mm) {
> -		seq_printf(m, "%lu\n", mm->ksm_merging_pages);
> -		mmput(mm);
> -	}
> -
> -	return 0;
> -}
>  static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,
>  				struct pid *pid, struct task_struct *task)
>  {
> @@ -3348,7 +3335,6 @@ static const struct pid_entry tgid_base_stuff[] = {
>  	ONE("seccomp_cache", S_IRUSR, proc_pid_seccomp_cache),
>  #endif
>  #ifdef CONFIG_KSM
> -	ONE("ksm_merging_pages",  S_IRUSR, proc_pid_ksm_merging_pages),
>  	ONE("ksm_stat",  S_IRUSR, proc_pid_ksm_stat),
>  #endif
>  };
> @@ -3686,7 +3672,6 @@ static const struct pid_entry tid_base_stuff[] = {
>  	ONE("seccomp_cache", S_IRUSR, proc_pid_seccomp_cache),
>  #endif
>  #ifdef CONFIG_KSM
> -	ONE("ksm_merging_pages",  S_IRUSR, proc_pid_ksm_merging_pages),
>  	ONE("ksm_stat",  S_IRUSR, proc_pid_ksm_stat),
>  #endif
>  };
> -- 
> 2.25.1