From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 21 Sep 2001 06:21:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 21 Sep 2001 06:21:34 -0400 Received: from ns.ithnet.com ([217.64.64.10]:32270 "HELO heather.ithnet.com") by vger.kernel.org with SMTP id ; Fri, 21 Sep 2001 06:21:26 -0400 Date: Fri, 21 Sep 2001 12:21:15 +0200 From: Stephan von Krawczynski To: Bill Davidsen Cc: linux-kernel@vger.kernel.org Subject: Re: broken VM in 2.4.10-pre9 Message-Id: <20010921122115.271d1a1e.skraw@ithnet.com> In-Reply-To: In-Reply-To: <20010916204528.6fd48f5b.skraw@ithnet.com> Organization: ith Kommunikationstechnik GmbH X-Mailer: Sylpheed version 0.6.2 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 20 Sep 2001 23:16:55 -0400 (EDT) Bill Davidsen wrote: > On Sun, 16 Sep 2001, Stephan von Krawczynski wrote: > > > > Thinking again about it, I guess I would prefer a FIFO-list of allocated pages. > > This would allow to "know" the age simply by its position in the list. You > > wouldn't need a timestamp then, and even better it works equally well for > > systems with high vm load and low, because you do not deal with absolute time > > comparisons, but relative. > > That sounds pretty good for me. > > The problem is that when many things effect the optimal ratio of text, > data, buffer and free space a solution which doesn't measure all the > important factors will produce sub-optimal results. Your proposal is > simple and elegant, but I think it's too simple to produce good results. > See my reply to Linus' comments. Actually I did not really propose a method of valueing the several pros and cons in aging itself, but a very basic idea of how this could be done without fiddling around with page->members (like page->age) which always implies you have to walk down a whole list to get the full picture in case of urgent need for freeable pages. If you age something by re-arranging its position in a list you have the drawback of list-locking, but the gain of fast finding the best freeable pages by simply using the first ones in that list. Even better you can add whatever criteria you like to this aging, e.g. you could rearrange to let consecutive pages be freed together and so on, all would be pretty easy to achieve, and page-struct becomes even smaller. The more I think about it the better it sounds. Your opinion? Regards, Stephan