From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757291Ab2GCVHI (ORCPT ); Tue, 3 Jul 2012 17:07:08 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36514 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756194Ab2GCVHG (ORCPT ); Tue, 3 Jul 2012 17:07:06 -0400 Date: Tue, 3 Jul 2012 14:07:05 -0700 From: Andrew Morton To: Jiang Liu Cc: Mel Gorman , Tony Luck , Yinghai Lu , Xishi Qiu , KAMEZAWA Hiroyuki , KOSAKI Motohiro , David Rientjes , Minchan Kim , Keping Chen , , , , Jiang Liu Subject: Re: [PATCH] mm: setup pageblock_order before it's used by sparse Message-Id: <20120703140705.af23d4d3.akpm@linux-foundation.org> In-Reply-To: <1341047274-5616-1-git-send-email-jiang.liu@huawei.com> References: <1341047274-5616-1-git-send-email-jiang.liu@huawei.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 30 Jun 2012 17:07:54 +0800 Jiang Liu wrote: > From: Xishi Qiu > > On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium, > pageblock_order is a variable with default value of 0. It's set to the right > value by set_pageblock_order() in function free_area_init_core(). > > But pageblock_order may be used by sparse_init() before free_area_init_core() > is called along path: > sparse_init() > ->sparse_early_usemaps_alloc_node() > ->usemap_size() > ->SECTION_BLOCKFLAGS_BITS > ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * > NR_PAGEBLOCK_BITS) > > The uninitialized pageblock_size will cause memory wasting because usemap_size() > returns a much bigger value then it's really needed. > > For example, on an Itanium platform, > sparse_init() pageblock_order=0 usemap_size=24576 > free_area_init_core() before pageblock_order=0, usemap_size=24576 > free_area_init_core() after pageblock_order=12, usemap_size=8 > > That means 24K memory has been wasted for each section, so fix it by calling > set_pageblock_order() from sparse_init(). > > ... > > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -485,6 +485,9 @@ void __init sparse_init(void) > struct page **map_map; > #endif > > + /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */ > + set_pageblock_order(); > + > /* > * map is using big page (aka 2M in x86 64 bit) > * usemap is less one page (aka 24 bytes) It's a bit ugly calling set_pageblock_order() from both sparse_init() and from free_area_init_core(). Can we find a single place from which to call it? It looks like here: --- a/init/main.c~a +++ a/init/main.c @@ -514,6 +514,7 @@ asmlinkage void __init start_kernel(void __stop___param - __start___param, -1, -1, &unknown_bootoption); + set_pageblock_order(); jump_label_init(); /* would do the trick? (free_area_init_core is __paging_init and set_pageblock_order() is __init. I'm too lazy to work out if that's wrong) From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx128.postini.com [74.125.245.128]) by kanga.kvack.org (Postfix) with SMTP id 43FFB6B009D for ; Tue, 3 Jul 2012 17:07:07 -0400 (EDT) Date: Tue, 3 Jul 2012 14:07:05 -0700 From: Andrew Morton Subject: Re: [PATCH] mm: setup pageblock_order before it's used by sparse Message-Id: <20120703140705.af23d4d3.akpm@linux-foundation.org> In-Reply-To: <1341047274-5616-1-git-send-email-jiang.liu@huawei.com> References: <1341047274-5616-1-git-send-email-jiang.liu@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Jiang Liu Cc: Mel Gorman , Tony Luck , Yinghai Lu , Xishi Qiu , KAMEZAWA Hiroyuki , KOSAKI Motohiro , David Rientjes , Minchan Kim , Keping Chen , linux-mm@kvack.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, Jiang Liu On Sat, 30 Jun 2012 17:07:54 +0800 Jiang Liu wrote: > From: Xishi Qiu > > On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium, > pageblock_order is a variable with default value of 0. It's set to the right > value by set_pageblock_order() in function free_area_init_core(). > > But pageblock_order may be used by sparse_init() before free_area_init_core() > is called along path: > sparse_init() > ->sparse_early_usemaps_alloc_node() > ->usemap_size() > ->SECTION_BLOCKFLAGS_BITS > ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * > NR_PAGEBLOCK_BITS) > > The uninitialized pageblock_size will cause memory wasting because usemap_size() > returns a much bigger value then it's really needed. > > For example, on an Itanium platform, > sparse_init() pageblock_order=0 usemap_size=24576 > free_area_init_core() before pageblock_order=0, usemap_size=24576 > free_area_init_core() after pageblock_order=12, usemap_size=8 > > That means 24K memory has been wasted for each section, so fix it by calling > set_pageblock_order() from sparse_init(). > > ... > > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -485,6 +485,9 @@ void __init sparse_init(void) > struct page **map_map; > #endif > > + /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */ > + set_pageblock_order(); > + > /* > * map is using big page (aka 2M in x86 64 bit) > * usemap is less one page (aka 24 bytes) It's a bit ugly calling set_pageblock_order() from both sparse_init() and from free_area_init_core(). Can we find a single place from which to call it? It looks like here: --- a/init/main.c~a +++ a/init/main.c @@ -514,6 +514,7 @@ asmlinkage void __init start_kernel(void __stop___param - __start___param, -1, -1, &unknown_bootoption); + set_pageblock_order(); jump_label_init(); /* would do the trick? (free_area_init_core is __paging_init and set_pageblock_order() is __init. I'm too lazy to work out if that's wrong) -- 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