Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751226AbWCKVI3 (ORCPT ); Sat, 11 Mar 2006 16:08:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751280AbWCKVI3 (ORCPT ); Sat, 11 Mar 2006 16:08:29 -0500 Received: from amsfep17-int.chello.nl ([213.46.243.15]:7327 "EHLO amsfep12-int.chello.nl") by vger.kernel.org with ESMTP id S1751226AbWCKVI3 (ORCPT ); Sat, 11 Mar 2006 16:08:29 -0500 Subject: Re: [PATCH 00/03] Unmapped: Separate unmapped and mapped pages From: Peter Zijlstra To: Magnus Damm Cc: Peter Zijlstra , Magnus Damm , Linux Kernel , linux-mm@kvack.org In-Reply-To: References: <20060310034412.8340.90939.sendpatchset@cherry.local> <1141993351.8165.10.camel@twins> Content-Type: text/plain Date: Sat, 11 Mar 2006 22:08:15 +0100 Message-Id: <1142111295.2928.14.camel@lappy> Mime-Version: 1.0 X-Mailer: Evolution 2.5.92 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1410 Lines: 31 On Fri, 2006-03-10 at 14:38 +0100, Magnus Damm wrote: > On 3/10/06, Peter Zijlstra wrote: > > Breaking the LRU in two like this breaks the page ordering, which makes > > it possible for pages to stay resident even though they have much less > > activity than pages that do get reclaimed. > > Yes, true. But this happens already with a per-zone LRU. LRU pages > that happen to end up in the DMA zone will probably stay there a > longer time than pages in the normal zone. That does not mean it is > right to break the page ordering though, I'm just saying it happens > already and the oldest piece of data in the global system will not be > reclaimed first - instead there are priorities such as unmapped pages > will be reclaimed over mapped and so on. (I strongly feel that there > should be per-node LRU:s, but that's another story) If reclaim works right* there is equal pressure on each zone (proportional to their size) and hence each page will have an equal life time expectancy. (*) this is of course not possible for all workloads, however balance_pgdat and the page allocator take pains to make it as true as possible. Peter - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/