Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936560Ab3DKDqe (ORCPT ); Wed, 10 Apr 2013 23:46:34 -0400 Received: from mail-qa0-f44.google.com ([209.85.216.44]:35652 "EHLO mail-qa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934484Ab3DKDqc (ORCPT ); Wed, 10 Apr 2013 23:46:32 -0400 Message-ID: <51663210.7070502@gmail.com> Date: Thu, 11 Apr 2013 11:46:24 +0800 From: Simon Jeons User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: Christoph Lameter CC: Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mel Gorman , Hugh Dickins , Rik van Riel , Minchan Kim , Pekka Enberg , Matt Mackall Subject: Re: [PATCH 2/3] mm, slub: count freed pages via rcu as this task's reclaimed_slab References: <1365470478-645-1-git-send-email-iamjoonsoo.kim@lge.com> <1365470478-645-2-git-send-email-iamjoonsoo.kim@lge.com> <5163E194.3080600@gmail.com> <0000013def363b50-9a16dd09-72ad-494f-9c25-17269fc3aab3-000000@email.amazonses.com> <5164DA6A.5060607@gmail.com> <0000013df43a48e5-6addd57e-952b-4754-848e-6d454b0a906c-000000@email.amazonses.com> In-Reply-To: <0000013df43a48e5-6addd57e-952b-4754-848e-6d454b0a906c-000000@email.amazonses.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1800 Lines: 43 Hi Christoph, On 04/10/2013 09:54 PM, Christoph Lameter wrote: > On Wed, 10 Apr 2013, Simon Jeons wrote: > >> It seems that you misunderstand my question. I don't doubt slab/slub can use >> high order pages. However, what I focus on is why slab/slub can use compound >> page, PageCompound() just on behalf of hugetlbfs pages or thp pages which >> should used by apps, isn't it? > I am not entirely clear on what you are asking for. The following gives a > couple of answers to what I guess the question was. > > THP pages and user pages are on the lru and are managed differently. > The slab allocators cannot work with those pages. > > Slab allocators *can* allocate higher order pages therefore they could > allocate a page of the same order as huge pages and manage it that way. > > However there is no way that these pages could be handled like THP pages > since they cannot be broken up (unless we add the capability to move slab > objects which I wanted to do for a long time). > > > You can boot a Linux system that uses huge pages for slab allocation > by specifying the following parameter on the kernel command line. > > slub_min_order=9 > > The slub allocator will start using huge pages for all its storage > needs. You need a large number of huge pages to do this. Lots of memory > is going to be lost due to fragmentation but its going to be fast since > the slowpaths are rarely used. OOMs due to reclaim failure become much > more likely ;-). > It seems that I need to simple my question. All pages which order >=1 are compound pages? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/