From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 0C4EF8D0017 for ; Mon, 15 Nov 2010 09:48:56 -0500 (EST) Message-ID: <4CE14848.2060805@redhat.com> Date: Mon, 15 Nov 2010 09:48:40 -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> 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 11/15/2010 04:05 AM, Minchan Kim wrote: > On Mon, Nov 15, 2010 at 5:47 PM, Peter Zijlstra wrote: >> On Mon, 2010-11-15 at 15:07 +0900, Minchan Kim wrote: >>> I wonder what's the problem in Peter's patch 'drop behind'. >>> http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg179576.html >>> >>> Could anyone tell me why it can't accept upstream? >> >> Read the thread, its quite clear nobody got convinced it was a good idea >> and wanted to fix the use-once policy, then Rik rewrote all of >> page-reclaim. >> > > Thanks for the information. > I hope this is a chance to rethink about it. > Rik, Could you give us to any comment about this idea? At the time, there were all kinds of general problems in page reclaim that all needed to be fixed. Peter's patch was mostly a band-aid for streaming IO. However, now that most of the other page reclaim problems seem to have been resolved, it would be worthwhile to test whether Peter's drop-behind approach gives an additional improvement. I could see it help by getting rid of already-read pages earlier, leaving more space for read-ahead data. I suspect it would do fairly little to protect the working set, because we do not scan the active file list at all unless it grows to be larger than the inactive file list. -- 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