From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id AD1168D0030 for ; Fri, 29 Oct 2010 08:41:31 -0400 (EDT) Received: from eu_spt1 (mailout2.w1.samsung.com [210.118.77.12]) by mailout2.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTP id <0LB100AK2XX2QB@mailout2.w1.samsung.com> for linux-mm@kvack.org; Fri, 29 Oct 2010 13:41:26 +0100 (BST) Received: from linux.samsung.com ([106.116.38.10]) by spt1.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0LB1009GVXX2EB@spt1.w1.samsung.com> for linux-mm@kvack.org; Fri, 29 Oct 2010 13:41:26 +0100 (BST) Date: Fri, 29 Oct 2010 14:43:51 +0200 From: =?utf-8?B?TWljaGHFgiBOYXphcmV3aWN6?= Subject: Re: [RFC][PATCH 0/3] big chunk memory allocator v2 In-reply-to: <20101029122928.GA17792@gargoyle.fritz.box> Message-id: MIME-version: 1.0 Content-type: text/plain; charset=utf-8; format=flowed; delsp=yes Content-transfer-encoding: Quoted-Printable References: <20101026190042.57f30338.kamezawa.hiroyu@jp.fujitsu.com> <20101029103154.GA10823@gargoyle.fritz.box> <20101029195900.88559162.kamezawa.hiroyu@jp.fujitsu.com> <20101029122928.GA17792@gargoyle.fritz.box> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki , Andi Kleen Cc: Minchan Kim , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , KOSAKI Motohiro , "fujita.tomonori@lab.ntt.co.jp" , "felipe.contreras@gmail.com" , linux-arm-kernel , Jonathan Corbet , Russell King , Pawel Osciak , Peter Zijlstra List-ID: >>>> When I was posting CMA, it had been suggested to create a new migra= tion type >>>> dedicated to contiguous allocations. I think I already did that an= d thanks to >>>> this new migration type we have (i) an area of memory that only acc= epts movable >>>> and reclaimable pages and >> Andi Kleen wrote: >>> Aka highmem next generation :-( > On Fri, Oct 29, 2010 at 11:59:00AM +0100, KAMEZAWA Hiroyuki wrote: >> yes. But Nick's new shrink_slab() may be a new help even without >> new zone. On Fri, 29 Oct 2010 14:29:28 +0200, Andi Kleen wr= ote: > You would really need callbacks into lots of code. Christoph > used to have some patches for directed shrink of dcache/icache, > but they are currently not on the table. > > I don't think Nick's patch does that, he simply optimizes the existing= > shrinker (which in practice tends to not shrink a lot) to be a bit > less wasteful. > > The coverage will never be 100% in any case. So you always have to > make a choice between movable or fully usable. That's essentially > highmem with most of its problems. Yep. >>>> (ii) is used only if all other (non-reserved) pages have >>>> been allocated. >>> That will be near always the case after some uptime, as memory fills= up >>> with caches. Unless you do early reclaim? Hmm... true. Still the point remains that only movable and reclaimable = pages are allowed in the marked regions. This in effect means that from unmovable= pages point of view, the area is unusable but I havn't thought of any other wa= y to guarantee that because of fragmentation, long sequence of free/movable/r= eclaimable pages is available. >> memory migration always do work with alloc_page() for getting migrati= on target >> pages. So, memory will be reclaimed if filled by cache. > > Was talking about that paragraph CMA, not your patch. > > If I understand it correctly CMA wants to define > a new zone which is somehow similar to movable, but only sometimes use= d > when another zone is full (which is the usual state in normal > operation actually) > > It was unclear to me how this was all supposed to work. At least > as described in the paragraph it cannot I think. It's not a new zone, just a new migrate type. I haven't tested it yet, but the idea is that once pageblock's migrate type is set to this new MIGRATE_CMA type, buddy allocator never changes it and in fallback list it's put on the end of entries for MIGRATE_RECLAIMABLE and MIGRATE_MOVABLE. If I got everything right, this means that pages from MIGRATE_CMA pagebl= ocks are available for movable and reclaimable allocations but not for unmova= ble. -- = Best regards, _ _ | Humble Liege of Serenely Enlightened Majesty of o' \,=3D./ `o | Computer Science, Micha=C5=82 "mina86" Nazarewicz (o o) +----[mina86*mina86.com]---[mina86*jabber.org]----ooO--(_)--Ooo-- -- 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