From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: NUMA policy issues with ZONE_MOVABLE From: Lee Schermerhorn In-Reply-To: <20070725111646.GA9098@skynet.ie> References: <20070725111646.GA9098@skynet.ie> Content-Type: text/plain Date: Wed, 25 Jul 2007 10:30:23 -0400 Message-Id: <1185373824.5604.30.camel@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: Christoph Lameter , linux-mm@kvack.org, ak@suse.de, KAMEZAWA Hiroyuki , akpm@linux-foundation.org List-ID: On Wed, 2007-07-25 at 12:16 +0100, Mel Gorman wrote: > On (24/07/07 21:20), Christoph Lameter didst pronounce: > > The outcome of the 2.6.23 merge was surprising. No antifrag but only > > ZONE_MOVABLE. ZONE_MOVABLE is the highest zone. > > > > 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? > > > > No but it has to be dealt with. I would have preferred this was highlighted > earlier but there is a candidate fix below. It appears to be the minimum > solution to allow policies to work as they do today but remaining compatible > with ZONE_MOVABLE. It works by > > o check_highest_zone will be the highest populated zone that is not ZONE_MOVEABLE Ah, sick minds think alike... ;-) Lee -- 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