From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e32.co.us.ibm.com (8.12.10/8.12.9) with ESMTP id i9QLR5Ex540922 for ; Tue, 26 Oct 2004 17:27:05 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id i9QLR5Jm418502 for ; Tue, 26 Oct 2004 15:27:05 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11/8.12.11) with ESMTP id i9QLR5Pw004545 for ; Tue, 26 Oct 2004 15:27:05 -0600 Subject: Re: [Lhms-devel] Re: 150 nonlinear From: Dave Hansen In-Reply-To: <417EBFB3.5000803@kolumbus.fi> References: <1098815779.4861.26.camel@localhost> <417EA06B.5040609@kolumbus.fi> <1098819748.5633.0.camel@localhost> <417EB684.1060100@kolumbus.fi> <1098824141.6188.1.camel@localhost> <417EBFB3.5000803@kolumbus.fi> Content-Type: text/plain; charset=ISO-8859-1 Message-Id: <1098826023.7172.4.camel@localhost> Mime-Version: 1.0 Date: Tue, 26 Oct 2004 14:27:03 -0700 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mika =?ISO-8859-1?Q?Penttil=E4?= Cc: Andy Whitcroft , lhms , linux-mm List-ID: On Tue, 2004-10-26 at 14:20, Mika Penttila wrote: > "There are two problems that are being solved: having a sparse layout > requiring splitting up mem_map (solved by discontigmem and your > nonlinear), and supporting non-linear phys to virt relationships (Dave > M's implentation which does the mem_map split as well)." > > > so what's the split? So, mem_map is normally laid out so that, if you have 1GB of memory, the memory for 0x00000000 is at mem_map[0], and the memory for the last page (at 1GB - 1 page) is at mem_map[1<<30 / PAGE_SIZE - 1]. That's fine and dandy for most systems. But, imagine that you have some memory on a funky machine where you have 2GB of memory, but it is laid out like this: 0-1 GB - first 1 GB 1-100 GB - empty 100-101 GB - second 1 GB Then, you'd need to have mem_map sized the same as a 101GB system on your dinky 2GB system (disregard the ia64 implementation). The split I'm referring to is cutting mem_map[] up into pieces for each contiguous section of memory. Make sense? -- Dave -- 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: aart@kvack.org