From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhang Yanfei Subject: Re: [PATCH v10 1/7] mm: support madvise(MADV_FREE) Date: Tue, 8 Jul 2014 11:54:12 +0800 Message-ID: <53BB6B64.1080807@cn.fujitsu.com> References: <1404694438-10272-1-git-send-email-minchan@kernel.org> <1404694438-10272-2-git-send-email-minchan@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1404694438-10272-2-git-send-email-minchan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Minchan Kim Cc: Andrew Morton , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Michael Kerrisk , Linux API , Hugh Dickins , Johannes Weiner , Rik van Riel , KOSAKI Motohiro , Mel Gorman , Jason Evans , "Kirill A. Shutemov" List-Id: linux-api@vger.kernel.org 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