From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 789C16B005C for ; Tue, 12 May 2009 00:35:13 -0400 (EDT) Date: Tue, 12 May 2009 12:35:22 +0800 From: Wu Fengguang 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> Sender: owner-linux-mm@kvack.org 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" List-ID: 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 -- 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