From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id DAA146B0087 for ; Wed, 17 Nov 2010 22:25:14 -0500 (EST) Message-ID: <4CE49C8B.2050005@redhat.com> Date: Wed, 17 Nov 2010 22:24:59 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: fadvise DONTNEED implementation (or lack thereof) References: <20101109162525.BC87.A69D9226@jp.fujitsu.com> <877hgmr72o.fsf@gmail.com> <20101114140920.E013.A69D9226@jp.fujitsu.com> <1289810825.2109.469.camel@laptop> <4CE14848.2060805@redhat.com> <4CE40129.9060103@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Peter Zijlstra , KOSAKI Motohiro , Ben Gamari , linux-kernel@vger.kernel.org, rsync@lists.samba.org, linux-mm@kvack.org, Wu Fengguang List-ID: On 11/17/2010 09:47 PM, Minchan Kim wrote: > On Thu, Nov 18, 2010 at 1:22 AM, Rik van Riel wrote: >> On 11/17/2010 05:16 AM, Minchan Kim wrote: >> >>> Absolutely. But how about rsync's two touch? >>> It can evict working set. >>> >>> I need the time for investigation. >>> Thanks for the comment. >> >> Maybe we could exempt MADV_SEQUENTIAL and FADV_SEQUENTIAL >> touches from promoting the page to the active list? >> > > The problem is non-mapped file page. > non-mapped file page promotion happens by only mark_page_accessed. > But it doesn't enough information to prevent promotion(ex, vma or file) I believe we have enough information in filemap.c and can just pass that as a parameter to mark_page_accessed. > Here is another idea. > Current problem is following as. > User can use fadivse with FADV_DONTNEED. > But problem is that it can't affect when it meet dirty pages. > So user have to sync dirty page before calling fadvise with FADV_DONTNEED. > It would lose performance. > > Let's add some semantic of FADV_DONTNEED. > It invalidates only pages which are not dirty. > If it meets dirty page, let's move the page into inactive's tail or head. > If we move the page into tail, shrinker can move it into head again > for deferred write if it isn't written the backed device. That sounds like a good idea. -- All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org