linux-kernel - Re: [PATCH v10 1/7] mm: support madvise(MADV

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Message-ID: <53BB6B64.1080807@cn.fujitsu.com>
Date:	Tue, 8 Jul 2014 11:54:12 +0800
From:	Zhang Yanfei <zhangyanfei@...fujitsu.com>
To:	Minchan Kim <minchan@...nel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Linux API <linux-api@...r.kernel.org>,
	Hugh Dickins <hughd@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Jason Evans <je@...com>,
	"Kirill A. Shutemov" <kirill@...temov.name>
Subject: Re: [PATCH v10 1/7] mm: support madvise(MADV_FREE)

Hi Minchan,

On 07/07/2014 08:53 AM, Minchan Kim wrote:
> Linux doesn't have an ability to free pages lazy while other OS
> already have been supported that named by madvise(MADV_FREE).
> 
> The gain is clear that kernel can discard freed pages rather than
> swapping out or OOM if memory pressure happens.
> 
> Without memory pressure, freed pages would be reused by userspace
> without another additional overhead(ex, page fault + allocation
> + zeroing).
> 
> How to work is following as.
> 
> When madvise syscall is called, VM clears dirty bit of ptes of
> the range. 

This should be updated because the implementation has been changed.
It also remove the page from the swapcache if it is.

Thank you for your effort!

-- 
Thanks.
Zhang Yanfei
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