linux-kernel - Re: [PATCH v4 2/4] zram: implement deduplication in zram

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Message-ID: <20170426021452.GA673@jagdpanzerIV.localdomain>
Date:   Wed, 26 Apr 2017 11:14:52 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     js1304@...il.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-kernel@...r.kernel.org, kernel-team@....com,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v4 2/4] zram: implement deduplication in zram

Hello,

On (04/26/17 09:52), js1304@...il.com wrote:
[..]
>  	ret = scnprintf(buf, PAGE_SIZE,
> -			"%8llu %8llu %8llu %8lu %8ld %8llu %8lu\n",
> +			"%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu %8llu\n",
>  			orig_size << PAGE_SHIFT,
>  			(u64)atomic64_read(&zram->stats.compr_data_size),
>  			mem_used << PAGE_SHIFT,
>  			zram->limit_pages << PAGE_SHIFT,
>  			max_used << PAGE_SHIFT,
>  			(u64)atomic64_read(&zram->stats.same_pages),
> -			pool_stats.pages_compacted);
> +			pool_stats.pages_compacted,
> +			zram_dedup_dup_size(zram),
> +			zram_dedup_meta_size(zram));

hm... should't we subtract zram_dedup_dup_size(zram) from
->stats.compr_data_size? we don't use extra memory for dedupped
pages. or don't inc ->stats.compr_data_size for dedupped pages?

for instance, same_page_write() does not inc ->stats.compr_data_size,
while successful zram_dedup_find() does (in __zram_bvec_write()).

	-ss