From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932581AbVKCWhw (ORCPT ); Thu, 3 Nov 2005 17:37:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932584AbVKCWhw (ORCPT ); Thu, 3 Nov 2005 17:37:52 -0500 Received: from dvhart.com ([64.146.134.43]:18095 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S932581AbVKCWhv (ORCPT ); Thu, 3 Nov 2005 17:37:51 -0500 Date: Thu, 03 Nov 2005 14:37:46 -0800 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" To: Linus Torvalds Cc: Mel Gorman , Arjan van de Ven , Nick Piggin , Dave Hansen , Ingo Molnar , Andrew Morton , kravetz@us.ibm.com, linux-mm , Linux Kernel Mailing List , lhms , Arjan van de Ven Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-ID: <43370000.1131057466@flay> In-Reply-To: References: <4366C559.5090504@yahoo.com.au><4366D469.2010202@yahoo.com.au><20051101135651.GA8502@elte.hu><1130854224.14475.60.camel@localhost><20051101142959.GA9272@elte.hu><1130856555.14475.77.camel@localhost><20051101150142.GA10636@elte.hu><1130858580.14475.98.camel@localhost><20051102084946.GA3930@elte.hu><436880B8.1050207@yahoo.com.au><1130923969.15627.11.camel@localhost><43688B74.20002@yahoo.com.au><255360000.1130943722@[10.10.2.4]><4369824E.2020407@yahoo.com.au><306020000.1131032193@[10.10.2.4]><1131032422.2839.8.camel@laptopd505.fenrus.org> <309420000.1131036740@[10.10.2.4]> <311050000.1131040276@[10.10.2.4]><314040000.1131043735@[10.10.2.4]> X-Mailer: Mulberry/2.1.2 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> Ha. Just because I don't think I made you puke hard enough already with >> foul approximations ... for order 2, I think it's > > Your basic fault is in believing that the free watermark would stay > constant. > > That's insane. > > Would you keep 8MB free on a 64MB system? > > Would you keep 8MB free on a 8GB system? > > The point being, that if you start with insane assumptions, you'll get > insane answers. Ummm. I was basing it on what we actually do now in the code, unless I misread it, which is perfectly possible. Do you want this patch? diff -purN -X /home/mbligh/.diff.exclude linux-2.6.14/mm/page_alloc.c 2.6.14-no_water_cap/mm/page_alloc.c --- linux-2.6.14/mm/page_alloc.c 2005-10-27 18:52:20.000000000 -0700 +++ 2.6.14-no_water_cap/mm/page_alloc.c 2005-11-03 14:36:06.000000000 -0800 @@ -2387,8 +2387,6 @@ static void setup_per_zone_pages_min(voi min_pages = zone->present_pages / 1024; if (min_pages < SWAP_CLUSTER_MAX) min_pages = SWAP_CLUSTER_MAX; - if (min_pages > 128) - min_pages = 128; zone->pages_min = min_pages; } else { /* if it's a lowmem zone, reserve a number of pages > The _correct_ assumption is that you aim to keep some fixed percentage of > memory free. With that assumption and your math, finding higher-order > pages is equally hard regardless of amount of memory. That would, indeed, make more sense. > Now, your math then doesn't allow for the fact that buddy automatically > coalesces for you, so in fact things get _easier_ with more memory, but > hey, that needs more math than I can come up with (I never did it as math, > only as simulations with allocation patterns - "smart people use math, > plodding people just try to simulate an estimate" ;) Not sure what people who do math, but wrongly, are called, but I'm sure it's not polite, and I'm sure I'm one of those ;-) M.