Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934704Ab3DHBst (ORCPT ); Sun, 7 Apr 2013 21:48:49 -0400 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:57345 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934662Ab3DHBss (ORCPT ); Sun, 7 Apr 2013 21:48:48 -0400 X-AuditID: 9c93016f-b7c18ae000002f5f-70-516221fd7940 Date: Mon, 8 Apr 2013 10:48:45 +0900 From: Minchan Kim To: Simon Jeons Cc: Hugh Dickins , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dan Magenheimer , Seth Jennings , Nitin Gupta , Konrad Rzeszutek Wilk , Shaohua Li , Kamezawa Hiroyuki Subject: Re: [RFC] mm: remove swapcache page early Message-ID: <20130408014845.GB6394@blaptop> References: <1364350932-12853-1-git-send-email-minchan@kernel.org> <515ADFCF.4010209@gmail.com> <51611F94.7060801@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51611F94.7060801@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1834 Lines: 52 Hello Simon, On Sun, Apr 07, 2013 at 03:26:12PM +0800, Simon Jeons wrote: > Ping Minchan. > On 04/02/2013 09:40 PM, Simon Jeons wrote: > >Hi Hugh, > >On 03/28/2013 05:41 AM, Hugh Dickins wrote: > >>On Wed, 27 Mar 2013, Minchan Kim wrote: > >> > >>>Swap subsystem does lazy swap slot free with expecting the page > >>>would be swapped out again so we can't avoid unnecessary write. > >> so we can avoid unnecessary write. > > > >If page can be swap out again, which codes can avoid unnecessary > >write? Could you point out to me? Thanks in advance. ;-) Look at shrink_page_list. 1) PageAnon(page) && !PageSwapCache() 2) add_to_swap's SetPageDirty 3) __remove_mapping P.S) It seems you are misunderstanding. Here isn't proper place to ask a question for your understanding the code. As I know, there are some project(ex, kernelnewbies) and books for study and sharing the knowledge linux kernel. I recommend Mel's "Understand the Linux Virtual Memory Manager". It's rather outdated but will be very helpful to understand VM of linux kernel. You can get it freely but I hope you pay for. So if author become a billionaire by selecting best book in Amazon, he might print out second edition which covers all of new VM features and may solve all of you curiosity. It would be a another method to contribute open source project. :) I believe you talented developers can catch it up with reading the code enoughly and find more bonus knowledge. I think it's why our senior developers yell out RTFM and I follow them. Cheers! -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/