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From:   "Huang, Ying" <ying.huang@intel.com>
To:     Li Zhijian <lizhijian@fujitsu.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <rafael@kernel.org>, <linux-mm@kvack.org>, <y-goto@fujitsu.com>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 2/4] mm/vmstat: Move pgdemote_* to per-node stats
In-Reply-To: <20231102025648.1285477-3-lizhijian@fujitsu.com> (Li Zhijian's
        message of "Thu, 2 Nov 2023 10:56:46 +0800")
References: <20231102025648.1285477-1-lizhijian@fujitsu.com>
        <20231102025648.1285477-3-lizhijian@fujitsu.com>
Date:   Thu, 02 Nov 2023 12:56:18 +0800
Message-ID: <874ji43g99.fsf@yhuang6-desk2.ccr.corp.intel.com>
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Li Zhijian <lizhijian@fujitsu.com> writes:

> This is a prepare to improve the demotion profiling in the later
> patches.

I think that this patch has its value even without the following
patches.  So, don't need to define it as preparation.

> Per-node demotion stats help users to quickly identify which
> node is in hige stree, and take some special operations if needed.

Better to add more description.  For example, memory pressure on one
node, etc.

> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>

After addressing the comments above, feel free to add

Acked-by: "Huang, Ying" <ying.huang@intel.com>

--
Best Regards,
Huang, Ying

> ---
>  include/linux/mmzone.h        | 4 ++++
>  include/linux/vm_event_item.h | 3 ---
>  mm/vmscan.c                   | 3 ++-
>  mm/vmstat.c                   | 6 +++---
>  4 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 4106fbc5b4b3..ad0309eea850 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -206,6 +206,10 @@ enum node_stat_item {
>  #ifdef CONFIG_NUMA_BALANCING
>  	PGPROMOTE_SUCCESS,	/* promote successfully */
>  	PGPROMOTE_CANDIDATE,	/* candidate pages to promote */
> +	/* PGDEMOTE_*: pages demoted */
> +	PGDEMOTE_KSWAPD,
> +	PGDEMOTE_DIRECT,
> +	PGDEMOTE_KHUGEPAGED,
>  #endif
>  	NR_VM_NODE_STAT_ITEMS
>  };
> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> index 8abfa1240040..d1b847502f09 100644
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -41,9 +41,6 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
>  		PGSTEAL_KSWAPD,
>  		PGSTEAL_DIRECT,
>  		PGSTEAL_KHUGEPAGED,
> -		PGDEMOTE_KSWAPD,
> -		PGDEMOTE_DIRECT,
> -		PGDEMOTE_KHUGEPAGED,
>  		PGSCAN_KSWAPD,
>  		PGSCAN_DIRECT,
>  		PGSCAN_KHUGEPAGED,
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 6f13394b112e..2f1fb4ec3235 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1678,7 +1678,8 @@ static unsigned int demote_folio_list(struct list_head *demote_folios,
>  		      (unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION,
>  		      &nr_succeeded);
>  
> -	__count_vm_events(PGDEMOTE_KSWAPD + reclaimer_offset(), nr_succeeded);
> +	mod_node_page_state(NODE_DATA(target_nid),
> +		    PGDEMOTE_KSWAPD + reclaimer_offset(), nr_succeeded);
>  
>  	return nr_succeeded;
>  }
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 00e81e99c6ee..f141c48c39e4 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1244,6 +1244,9 @@ const char * const vmstat_text[] = {
>  #ifdef CONFIG_NUMA_BALANCING
>  	"pgpromote_success",
>  	"pgpromote_candidate",
> +	"pgdemote_kswapd",
> +	"pgdemote_direct",
> +	"pgdemote_khugepaged",
>  #endif
>  
>  	/* enum writeback_stat_item counters */
> @@ -1275,9 +1278,6 @@ const char * const vmstat_text[] = {
>  	"pgsteal_kswapd",
>  	"pgsteal_direct",
>  	"pgsteal_khugepaged",
> -	"pgdemote_kswapd",
> -	"pgdemote_direct",
> -	"pgdemote_khugepaged",
>  	"pgscan_kswapd",
>  	"pgscan_direct",
>  	"pgscan_khugepaged",