From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 2FF196B0099 for ; Fri, 8 May 2009 18:23:08 -0400 (EDT) Date: Fri, 8 May 2009 15:15:32 -0700 From: Andrew Morton Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen Message-Id: <20090508151532.6769e702.akpm@linux-foundation.org> In-Reply-To: <20090508230045.5346bd32@lxorguk.ukuu.org.uk> References: <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> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Alan Cox Cc: fengguang.wu@intel.com, hannes@cmpxchg.org, peterz@infradead.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, kosaki.motohiro@jp.fujitsu.com, minchan.kim@gmail.com List-ID: On Fri, 8 May 2009 23:00:45 +0100 Alan Cox wrote: > > 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. Yep. But prior to 2.6.27(?) the same effect could be had by mmap()ing the file with or without PROT_EXEC. The patch restores a probably-beneficial heuristic which got lost in the LRU rewrite. So we're no worse than pre-2.6.27 kernels here. Plus there are probably more effective ways of getting that sort of boost, such as having a process running which simply touches your favoured pages at a suitable (and fairly low) frequency. -- 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