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Sender: Minchan Kim <minchan.kim@gmail.com>
Date:   Wed, 9 Nov 2022 13:55:45 -0800
From:   Minchan Kim <minchan@kernel.org>
To:     Nhat Pham <nphamcs@gmail.com>
Cc:     akpm@linux-foundation.org, hannes@cmpxchg.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, ngupta@vflare.org,
        senozhatsky@chromium.org, sjenning@redhat.com, ddstreet@ieee.org,
        vitaly.wool@konsulko.com
Subject: Re: [PATCH v3 3/5] zsmalloc: Add a LRU to zs_pool to keep track of
 zspages in LRU order
Message-ID: <Y2wh4b3oMaknNqGP@google.com>
References: <20221108193207.3297327-1-nphamcs@gmail.com>
 <20221108193207.3297327-4-nphamcs@gmail.com>
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On Tue, Nov 08, 2022 at 11:32:05AM -0800, Nhat Pham wrote:
> This helps determines the coldest zspages as candidates for writeback.
> 
> Signed-off-by: Nhat Pham <nphamcs@gmail.com>
> ---
>  mm/zsmalloc.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 326faa751f0a..600c40121544 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -239,6 +239,9 @@ struct zs_pool {
>  	/* Compact classes */
>  	struct shrinker shrinker;
> 
> +	/* List tracking the zspages in LRU order by most recently added object */
> +	struct list_head lru;
> +
>  #ifdef CONFIG_ZSMALLOC_STAT
>  	struct dentry *stat_dentry;
>  #endif
> @@ -260,6 +263,10 @@ struct zspage {
>  	unsigned int freeobj;
>  	struct page *first_page;
>  	struct list_head list; /* fullness list */
> +
> +	/* links the zspage to the lru list in the pool */
> +	struct list_head lru;

Please put the LRU logic under config ZSMALLOC_LRU since we don't need
the additional logic to others.