From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 3 Nov 2005 11:08:01 -0800 (PST) From: Linus Torvalds Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 In-Reply-To: <314040000.1131043735@[10.10.2.4]> Message-ID: 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]> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Martin J. Bligh" 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 List-ID: On Thu, 3 Nov 2005, Martin J. Bligh wrote: > > 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. 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. 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" ;) Linus -- 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