From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755329AbZEJOyV (ORCPT ); Sun, 10 May 2009 10:54:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753659AbZEJOyM (ORCPT ); Sun, 10 May 2009 10:54:12 -0400 Received: from mx2.redhat.com ([66.187.237.31]:54312 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753459AbZEJOyM (ORCPT ); Sun, 10 May 2009 10:54:12 -0400 Message-ID: <4A06EA08.1030102@redhat.com> Date: Sun, 10 May 2009 10:51:52 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 2.0.0.17 (X11/20080915) MIME-Version: 1.0 To: Alan Cox CC: KOSAKI Motohiro , Peter Zijlstra , Andrew Morton , Wu Fengguang , hannes@cmpxchg.org, linux-kernel@vger.kernel.org, tytso@mit.edu, linux-mm@kvack.org, elladan@eskimo.com, npiggin@suse.de, cl@linux-foundation.org, minchan.kim@gmail.com Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen References: <20090430181340.6f07421d.akpm@linux-foundation.org> <1241432635.7620.4732.camel@twins> <20090507121101.GB20934@localhost> <20090507151039.GA2413@cmpxchg.org> <20090507134410.0618b308.akpm@linux-foundation.org> <20090508081608.GA25117@localhost> <20090508125859.210a2a25.akpm@linux-foundation.org> <20090508230045.5346bd32@lxorguk.ukuu.org.uk> <2f11576a0905100159m32c36a9ep9fb7cc5604c60b2@mail.gmail.com> <1241946446.6317.42.camel@laptop> <2f11576a0905100236u15d45f7fm32d470776659cfec@mail.gmail.com> <20090510144533.167010a9@lxorguk.ukuu.org.uk> In-Reply-To: <20090510144533.167010a9@lxorguk.ukuu.org.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Alan Cox wrote: > On Sun, 10 May 2009 18:36:19 +0900 > KOSAKI Motohiro wrote: >> I don't oppose this policy. PROT_EXEC seems good viewpoint. > > I don't think it is that simple > > Not only can it be abused but some systems such as java have large > PROT_EXEC mapped environments, as do many other JIT based languages. On the file LRU side, or on the anon LRU side? > Secondly it moves the pressure from the storage volume holding the system > binaries and libraries to the swap device which already has to deal with > a lot of random (and thus expensive) I/O, as well as the users filestore > for mapped objects there - which may even be on a USB thumbdrive. Preserving the PROT_EXEC pages over streaming IO should not move much (if any) pressure from the file LRUs onto the swap-backed (anon) LRUs. > I still think the focus is on the wrong thing. We shouldn't be trying to > micro-optimise page replacement guesswork - we should be macro-optimising > the resulting I/O performance. Any ideas on how to achieve that? :) -- All rights reversed. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id BF8CB6B00B7 for ; Sun, 10 May 2009 10:51:35 -0400 (EDT) Message-ID: <4A06EA08.1030102@redhat.com> Date: Sun, 10 May 2009 10:51:52 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen References: <20090430181340.6f07421d.akpm@linux-foundation.org> <1241432635.7620.4732.camel@twins> <20090507121101.GB20934@localhost> <20090507151039.GA2413@cmpxchg.org> <20090507134410.0618b308.akpm@linux-foundation.org> <20090508081608.GA25117@localhost> <20090508125859.210a2a25.akpm@linux-foundation.org> <20090508230045.5346bd32@lxorguk.ukuu.org.uk> <2f11576a0905100159m32c36a9ep9fb7cc5604c60b2@mail.gmail.com> <1241946446.6317.42.camel@laptop> <2f11576a0905100236u15d45f7fm32d470776659cfec@mail.gmail.com> <20090510144533.167010a9@lxorguk.ukuu.org.uk> In-Reply-To: <20090510144533.167010a9@lxorguk.ukuu.org.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Alan Cox Cc: KOSAKI Motohiro , Peter Zijlstra , Andrew Morton , Wu Fengguang , hannes@cmpxchg.org, linux-kernel@vger.kernel.org, tytso@mit.edu, linux-mm@kvack.org, elladan@eskimo.com, npiggin@suse.de, cl@linux-foundation.org, minchan.kim@gmail.com List-ID: Alan Cox wrote: > On Sun, 10 May 2009 18:36:19 +0900 > KOSAKI Motohiro wrote: >> I don't oppose this policy. PROT_EXEC seems good viewpoint. > > I don't think it is that simple > > Not only can it be abused but some systems such as java have large > PROT_EXEC mapped environments, as do many other JIT based languages. On the file LRU side, or on the anon LRU side? > Secondly it moves the pressure from the storage volume holding the system > binaries and libraries to the swap device which already has to deal with > a lot of random (and thus expensive) I/O, as well as the users filestore > for mapped objects there - which may even be on a USB thumbdrive. Preserving the PROT_EXEC pages over streaming IO should not move much (if any) pressure from the file LRUs onto the swap-backed (anon) LRUs. > I still think the focus is on the wrong thing. We shouldn't be trying to > micro-optimise page replacement guesswork - we should be macro-optimising > the resulting I/O performance. Any ideas on how to achieve that? :) -- 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