From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46A6D5E1.70407@yahoo.com.au> Date: Wed, 25 Jul 2007 14:47:29 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: NUMA policy issues with ZONE_MOVABLE References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: linux-mm@kvack.org, Lee Schermerhorn , ak@suse.de, KAMEZAWA Hiroyuki , Mel Gorman , akpm@linux-foundation.org List-ID: Christoph Lameter wrote: > The outcome of the 2.6.23 merge was surprising. No antifrag but only > ZONE_MOVABLE. ZONE_MOVABLE is the highest zone. ZONE_MOVABLE is the way to be able to guarantee contiguous memory for hotplug and hugetlb without wasting too much memory, and is very unintrusive for what it does. I think it was a good step forward. There is still disagreement about the antifrag patches, so what is surprising about this outcome? > For the NUMA layer this has some weird consequences if ZONE_MOVABLE is populated > > 1. It is the highest zone. > > 2. Thus policy_zone == ZONE_MOVABLE > > ZONE_MOVABLE contains only movable allocs by default. That is anonymous > pages and page cache pages? > > The NUMA layer only supports NUMA policies for the highest zone. > Thus NUMA policies can control anonymous pages and the page cache pages > allocated from ZONE_MOVABLE. > > However, NUMA policies will no longer affect non pagecache and non > anonymous allocations. So policies can no longer redirect slab allocations > and huge page allocations (unless huge page allocations are moved to > ZONE_MOVABLE). And there are likely other allocations that are not > movable. > > If ZONE_MOVABLE is off then things should be working as normal. > > Doesnt this mean that ZONE_MOVABLE is incompatible with CONFIG_NUMA? I guess it has similar problems as ZONE_HIGHMEM etc. I think the zoned allocator and NUMA was there first, so it might be more correct to say that mempolicies are incompatible with them :) But I thought you had plans to fix mempolicies to do zones better? What happened to that? -- SUSE Labs, Novell Inc. -- 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