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 810096B003D for ; Fri, 1 May 2009 16:06:22 -0400 (EDT) Message-ID: <49FB5623.3030403@redhat.com> Date: Fri, 01 May 2009 16:05:55 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] vmscan: evict use-once pages first (v2) References: <20090428044426.GA5035@eskimo.com> <20090428192907.556f3a34@bree.surriel.com> <1240987349.4512.18.camel@laptop> <20090429114708.66114c03@cuia.bos.redhat.com> <20090430072057.GA4663@eskimo.com> <20090430174536.d0f438dd.akpm@linux-foundation.org> <20090430205936.0f8b29fc@riellaptop.surriel.com> <20090430181340.6f07421d.akpm@linux-foundation.org> <20090430215034.4748e615@riellaptop.surriel.com> <20090430195439.e02edc26.akpm@linux-foundation.org> <49FB01C1.6050204@redhat.com> <20090501123541.7983a8ae.akpm@linux-foundation.org> In-Reply-To: <20090501123541.7983a8ae.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: elladan@eskimo.com, peterz@infradead.org, linux-kernel@vger.kernel.org, tytso@mit.edu, kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org List-ID: Andrew Morton wrote: > On Fri, 01 May 2009 10:05:53 -0400 > Rik van Riel wrote: >> This means we need to provide our working set protection >> on a per-list basis, by tweaking the scan rate or avoiding >> scanning of the active file list alltogether under certain >> conditions. >> >> As a side effect, this will help protect frequently accessed >> file pages (good for ftp and nfs servers), indirect blocks, >> inode buffers and other frequently used metadata. > > Yeah, but that's all internal-implementation-of-the-day details. It > just doesn't matter how the sausages are made. What we have learned is > that the policy of retaining mapped pages over unmapped pages, *all > other things being equal* leads to a more pleasing system. Well, retaining mapped pages is one of the implementations that lead to a more pleasing system. I suspect that a fully scan resistant active file list will show the same behaviour, as well as a few other desired behaviours that come in very handy in various server loads. Are you open to evaluating other methods that could lead, on desktop systems, to a behaviour similar to the one achieved by the preserve-mapped-pages mechanism? -- 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/ . Don't email: email@kvack.org