linux-kernel - Re: [PATCH v2 3/7] zsmalloc: support compaction

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Date:	Thu, 05 Mar 2015 14:18:17 +0900
From:	Heesub Shin <heesub.shin@...sung.com>
To:	Minchan Kim <minchan@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Juneho Choi <juno.choi@....com>, Gunho Lee <gunho.lee@....com>,
	Luigi Semenzato <semenzato@...gle.com>,
	Dan Streetman <ddstreet@...e.org>,
	Seth Jennings <sjennings@...iantweb.net>,
	Nitin Gupta <ngupta@...are.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	opensource.ganesh@...il.com
Subject: Re: [PATCH v2 3/7] zsmalloc: support compaction

Hello Minchan,

Nice work!

On 03/04/2015 02:01 PM, Minchan Kim wrote:
> +static void putback_zspage(struct zs_pool *pool, struct size_class *class,
> +				struct page *first_page)
> +{
> +	int class_idx;
> +	enum fullness_group fullness;
> +
> +	BUG_ON(!is_first_page(first_page));
> +
> +	get_zspage_mapping(first_page, &class_idx, &fullness);
> +	insert_zspage(first_page, class, fullness);
> +	fullness = fix_fullness_group(class, first_page);

Removal and re-insertion of zspage above can be eliminated, like this:

	fullness = get_fullness_group(first_page);
	insert_zspage(first_page, class, fullness);
	set_zspage_mapping(first_page, class->index, fullness);

regards,
heesub

>  	if (fullness == ZS_EMPTY) {
> +		zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> +			class->size, class->pages_per_zspage));
>  		atomic_long_sub(class->pages_per_zspage,
>  				&pool->pages_allocated);
> +
>  		free_zspage(first_page);
>  	}
>  }
> -EXPORT_SYMBOL_GPL(zs_free);
> +
--
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