From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e4.ny.us.ibm.com (8.12.10/8.12.9) with ESMTP id iAI2O6Kv455296 for ; Wed, 17 Nov 2004 21:24:06 -0500 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay04.pok.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id iAI2O5b3284260 for ; Wed, 17 Nov 2004 21:24:05 -0500 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11/8.12.11) with ESMTP id iAI2O5Hf024622 for ; Wed, 17 Nov 2004 21:24:05 -0500 Subject: Re: [Lhms-devel] [RFC] fix for hot-add enabled SRAT/BIOS and numa KVA areas From: Dave Hansen In-Reply-To: <1100743722.26335.644.camel@knk> References: <1100659057.26335.125.camel@knk> <1100711519.5838.2.camel@localhost> <1100743722.26335.644.camel@knk> Content-Type: text/plain Message-Id: <1100744644.17510.8.camel@localhost> Mime-Version: 1.0 Date: Wed, 17 Nov 2004 18:24:04 -0800 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: keith Cc: external hotplug mem list , linux-mm , Chris McDermott List-ID: On Wed, 2004-11-17 at 18:08, keith wrote: > I am not anticipating to support hot-add without config_nonlinear or > something similar which should provide more flexibility in allocation of > smaller section mem_maps. This is only a issue when booted as a > discontig system. We don't even consult the SRAT when we boot flat > (contiguous address space) so it is a non-issue. Once a system has been running for any length of time, finding any multi-order pages gets somewhat hard. For a 16M section, you're still talking about ~128k of mem_map, which is still an order 5 allocation. Nick's kswapd higher-order patches should help with this, though. > Wasting 500k of lowmem for memory that "might" be there is no good. I > don't think having to preallocate the mem_map for a hot-add is really > that good. What if the system never adds memory? What if it only adds > 8gig not 49g? The system is crippled because it reserves the lmem_map > it "might" do a hot add with? I have the feeling we'll eventually need a boot-time option for this reservation. Your patch, of course will work for now. Do you want me to pick it up in my tree? > I forgot the mention that without this patch my system does not boot > with the hot-add support enabled in the bios. Why not? I'm just curious what caused the actual failure. -- 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