From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 03 Nov 2005 10:51:14 -0800 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-ID: <314480000.1131043874@[10.10.2.4]> In-Reply-To: References: <4366C559.5090504@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]> <1131040786.2839.18.camel@laptopd505.fenrus.org> <312300000.1131041824@[10.10.2.4]> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Arjan van de Ven , Mel Gorman , 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: --Linus Torvalds wrote (on Thursday, November 03, 2005 10:44:14 -0800): > > > On Thu, 3 Nov 2005, Martin J. Bligh wrote: >> > >> > These days we have things like per-cpu lists in front of the buddy >> > allocator that will make fragmentation somewhat higher, but it's still >> > absolutely true that the page allocation layout is _not_ random. >> >> OK, well I'll quit torturing you with incorrect math if you'll concede >> that the situation gets much much worse as memory sizes get larger ;-) > > I don't remember the specifics (I did the stats several years ago), but if > I recall correctly, the low-order allocations actually got _better_ with > more memory, assuming you kept a fixed percentage of memory free. So you > actually needed _less_ memory free (in percentages) to get low-order > allocations reliably. Possibly, I can redo the calculations easily enough (have to go for now, but I just sent the other ones). But we don't keep a fixed percentage of memory free - we cap it ... perhaps we should though? M. -- 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