From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754078AbZELEfy (ORCPT ); Tue, 12 May 2009 00:35:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751064AbZELEfo (ORCPT ); Tue, 12 May 2009 00:35:44 -0400 Received: from mga03.intel.com ([143.182.124.21]:37678 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751052AbZELEfo (ORCPT ); Tue, 12 May 2009 00:35:44 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.41,179,1241420400"; d="scan'208";a="141735651" Date: Tue, 12 May 2009 12:35:22 +0800 From: Wu Fengguang To: Andrew Morton Cc: "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" Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen Message-ID: <20090512043522.GA17079@localhost> References: <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> <20090512025058.GA7518@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090512025058.GA7518@localhost> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 12, 2009 at 10:50:58AM +0800, Wu Fengguang wrote: > > Now. How do we know that this patch improves Linux? > > Hmm, it seems hard to get measurable performance numbers. > > But we know that the running executable code is precious and shall be > protected, and the patch protects them in this way: > > before patch: will be reclaimed if not referenced in I > after patch: will be reclaimed if not referenced in I+A s/will/may/, to be more exact. > where > A = time to fully scan the active file LRU > I = time to fully scan the inactive file LRU > > Note that normally A >> I. > > Therefore this patch greatly prolongs the in-cache time of executable code, > when there are moderate memory pressures. Thanks, Fengguang