Re: [PATCH v6 4/6] zsmalloc: Add a LRU to zs_pool to keep track of zspages in LRU order

From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Nhat Pham <nphamcs@gmail.com>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	minchan@kernel.org, ngupta@vflare.org, senozhatsky@chromium.org,
	sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com
Subject: Re: [PATCH v6 4/6] zsmalloc: Add a LRU to zs_pool to keep track of zspages in LRU order
Date: Tue, 22 Nov 2022 10:52:58 +0900	[thread overview]
Message-ID: <Y3wreqR1IRWFtSUz@google.com> (raw)
In-Reply-To: <20221119001536.2086599-5-nphamcs@gmail.com>

On (22/11/18 16:15), Nhat Pham wrote:
[..]
> @@ -1249,6 +1267,15 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
>  	obj_to_location(obj, &page, &obj_idx);
>  	zspage = get_zspage(page);
> 
> +#ifdef CONFIG_ZPOOL
> +	/* Move the zspage to front of pool's LRU */
> +	if (mm == ZS_MM_WO) {
> +		if (!list_empty(&zspage->lru))
> +			list_del(&zspage->lru);
> +		list_add(&zspage->lru, &pool->lru);
> +	}
> +#endif

Do we consider pages that were mapped for MM_RO/MM_RW as cold?
I wonder why, we use them, so technically they are not exactly
"least recently used".