From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 25D186B005C for ; Sun, 10 May 2009 05:07:31 -0400 (EDT) Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen From: Peter Zijlstra In-Reply-To: <2f11576a0905100159m32c36a9ep9fb7cc5604c60b2@mail.gmail.com> References: <20090430181340.6f07421d.akpm@linux-foundation.org> <20090501123541.7983a8ae.akpm@linux-foundation.org> <20090503031539.GC5702@localhost> <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> Content-Type: text/plain Date: Sun, 10 May 2009 11:07:26 +0200 Message-Id: <1241946446.6317.42.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Alan Cox , Andrew Morton , Wu Fengguang , hannes@cmpxchg.org, riel@redhat.com, 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: On Sun, 2009-05-10 at 17:59 +0900, KOSAKI Motohiro wrote: > 2009/5/9 Alan Cox : > >> The patch seems reasonable but the changelog and the (non-existent) > >> design documentation could do with a touch-up. > > > > Is it right that I as a user can do things like mmap my database > > PROT_EXEC to get better database numbers by making other > > stuff swap first ? > > > > You seem to be giving everyone a "nice my process up" hack. > > How about this? > if priority < DEF_PRIORITY-2, aggressive lumpy reclaim in > shrink_inactive_list() already > reclaim the active page forcely. > then, this patch don't change kernel reclaim policy. > > anyway, user process non-changable preventing "nice my process up > hack" seems makes sense to me. > > test result: > > echo 100 > /proc/sys/vm/dirty_ratio > echo 100 > /proc/sys/vm/dirty_background_ratio > run modified qsbench (use mmap(PROT_EXEC) instead malloc) > > active2active vs active2inactive ratio > before 5:5 > after 1:9 > > please don't ask performance number. I haven't reproduce Wu's patch > improvemnt ;) > > Wu, What do you think? I don't think this is desirable, like Andrew already said, there's tons of ways to defeat any of this and we've so far always priorized mappings over !mappings. Limiting this to only PROT_EXEC mappings is already less than it used to be. -- 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