From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx130.postini.com [74.125.245.130]) by kanga.kvack.org (Postfix) with SMTP id C90216B0006 for ; Tue, 9 Apr 2013 23:20:17 -0400 (EDT) Received: by mail-ia0-f182.google.com with SMTP id u20so17280iag.13 for ; Tue, 09 Apr 2013 20:20:17 -0700 (PDT) Message-ID: <5164DA6A.5060607@gmail.com> Date: Wed, 10 Apr 2013 11:20:10 +0800 From: Simon Jeons MIME-Version: 1.0 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> In-Reply-To: <0000013def363b50-9a16dd09-72ad-494f-9c25-17269fc3aab3-000000@email.amazonses.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: 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 Hi Christoph, On 04/09/2013 10:32 PM, Christoph Lameter wrote: > On Tue, 9 Apr 2013, Simon Jeons wrote: > >>> + int pages = 1 << compound_order(page); >> One question irrelevant this patch. Why slab cache can use compound >> page(hugetlbfs pages/thp pages)? They are just used by app to optimize tlb >> miss, is it? > Slab caches can use any order pages because these pages are never on > the LRU and are not part of the page cache. Large continuous physical > memory means that objects can be arranged in a more efficient way in the > page. This is particularly useful for larger objects where we might use a > lot of memory because objects do not fit well into a 4k page. > > It also reduces the slab page management if higher order pages are used. > In the case of slub the page size also determines the number of objects > that can be allocated/freed without the need for some form of > synchronization. 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? > -- 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