From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 4 Dec 2006 12:17:26 -0800 (PST) From: Christoph Lameter Subject: Re: [PATCH] Add __GFP_MOVABLE for callers to flag allocations that may be migrated In-Reply-To: <20061204120611.4306024e.akpm@osdl.org> Message-ID: References: <20061130170746.GA11363@skynet.ie> <20061130173129.4ebccaa2.akpm@osdl.org> <20061201110103.08d0cf3d.akpm@osdl.org> <20061204140747.GA21662@skynet.ie> <20061204113051.4e90b249.akpm@osdl.org> <20061204120611.4306024e.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Mel Gorman , Linux Memory Management List , Linux Kernel Mailing List List-ID: On Mon, 4 Dec 2006, Andrew Morton wrote: > > The multi zone approach does not work with NUMA. NUMA only supports a > > single zone for memory policy control etc. > > Wot? memory policies are a per-vma thing? They only apply to "policy_zone" of a node. policy_zone can only take a single type of zone (has been like it forever). Multiple zones could become a nightmare with an exploding number of zones on zonelists. I.e. instead of 1k zones on a nodelist we now have 2k for two or even 4k if you want to have support for memory policies for 4 zones per node. We will then increase the search time through zonelists and have to manage all the memory in the different zones. Balancing is going to be difficult. > I suspect you'll have to live with that. I've yet to see a vaguely sane > proposal to otherwise prevent unreclaimable, unmoveable kernel allocations > from landing in a hot-unpluggable physical memory region. Mel's approach already mananges memory in a chunks of MAX_ORDER. It is easy to just restrict the unmovable types of allocation to a section of the zone. Then we should be doing some work to cut down the number of unmovable allocations. -- 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