linux-kernel - Re: [PATCH v2] more mapcount page as kpage could reduce total replacement times than fewer mapcount one in probability.

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Message-ID: <2460b794-92f0-d115-c729-bcfe33663e48@huawei.com>
Date:	Tue, 21 Jun 2016 09:57:54 +0800
From:	zhouxianrong <zhouxianrong@...wei.com>
To:	<linux-mm@...ck.org>
CC:	<akpm@...ux-foundation.org>, <hughd@...gle.com>,
	<aarcange@...hat.com>, <kirill.shutemov@...ux.intel.com>,
	<dave.hansen@...ux.intel.com>, <zhouchengming1@...wei.com>,
	<geliangtang@....com>, <linux-kernel@...r.kernel.org>,
	<zhouxiyu@...wei.com>, <wanghaijun5@...wei.com>
Subject: Re: [PATCH v2] more mapcount page as kpage could reduce total
 replacement times than fewer mapcount one in probability.

hey hugh:
     could you please give me some suggestion about this ?

On 2016/6/15 9:56, zhouxianrong@...wei.com wrote:
> From: z00281421 <z00281421@...esmail.huawei.com>
>
> more mapcount page as kpage could reduce total replacement times
> than fewer mapcount one when ksmd scan and replace among
> forked pages later.
>
> Signed-off-by: z00281421 <z00281421@...esmail.huawei.com>
> ---
>  mm/ksm.c |    8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 4786b41..4d530af 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -1094,6 +1094,14 @@ static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item,
>  {
>  	int err;
>
> +	/*
> +	 * select more mapcount page as kpage
> +	 */
> +	if (page_mapcount(page) < page_mapcount(tree_page)) {
> +		swap(page, tree_page);
> +		swap(rmap_item, tree_rmap_item);
> +	}
> +
>  	err = try_to_merge_with_ksm_page(rmap_item, page, NULL);
>  	if (!err) {
>  		err = try_to_merge_with_ksm_page(tree_rmap_item,
>