Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932658AbXAWCYz (ORCPT ); Mon, 22 Jan 2007 21:24:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932647AbXAWCYz (ORCPT ); Mon, 22 Jan 2007 21:24:55 -0500 Received: from mx1.redhat.com ([66.187.233.31]:35876 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932658AbXAWCYy (ORCPT ); Mon, 22 Jan 2007 21:24:54 -0500 Message-ID: <45B5703E.5010400@redhat.com> Date: Mon, 22 Jan 2007 21:17:34 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: Christoph Lameter CC: Balbir Singh , Andrea Arcangeli , Niki Hammler , linux-kernel@vger.kernel.org, Vaidyanathan Srinivasan Subject: Re: Why active list and inactive list? References: <45B55286.5060909@nobaq.net> <20070123003939.GY13798@opteron.random> <45B56575.10807@in.ibm.com> <45B569A4.3010006@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1631 Lines: 39 Christoph Lameter wrote: > On Mon, 22 Jan 2007, Rik van Riel wrote: > >> It would be really nice if we came up with a page replacement >> algorithm that did not need many extra heuristics to make it >> work... > > I guess the "clock" type algorithms are the most promising in that > area. What happened to all those advanced page replacement endeavors? > What is the most promising of those? You seem to have done a lot of work > on those. CLOCK-Pro seems the most promising algorithm, because it can act well both as a first level cache (operating system running applications) and as a second level cache (operating system running as a file server), because it tracks both recency and frequency well. However, there are a few unanswered questions on clock-pro. The big one is how we are to do some background aging in a clock-pro system, so referenced bits don't just pile up when the VM has enough memory - otherwise we might not know the right pages to evict when a new process starts up and starts allocating lots of memory. At least we've solved the problems of keeping track of the recently evicted pages in a cheap way, and balancing the pressure/hotness of different caches against each other. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. - 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/