Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753165Ab2KFTyi (ORCPT ); Tue, 6 Nov 2012 14:54:38 -0500 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:40947 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752637Ab2KFTyf (ORCPT ); Tue, 6 Nov 2012 14:54:35 -0500 From: "Srivatsa S. Bhat" Subject: [RFC PATCH 4/8] mm: Add helpers to retrieve node region and zone region for a given page To: akpm@linux-foundation.org, mgorman@suse.de, mjg59@srcf.ucam.org, paulmck@linux.vnet.ibm.com, dave@linux.vnet.ibm.com, maxime.coquelin@stericsson.com, loic.pallardy@stericsson.com, arjan@linux.intel.com, kmpark@infradead.org, kamezawa.hiroyu@jp.fujitsu.com, lenb@kernel.org, rjw@sisk.pl Cc: gargankita@gmail.com, amit.kachhap@linaro.org, svaidy@linux.vnet.ibm.com, thomas.abraham@linaro.org, santosh.shilimkar@ti.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Wed, 07 Nov 2012 01:23:19 +0530 Message-ID: <20121106195310.6941.91123.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20121106195026.6941.24662.stgit@srivatsabhat.in.ibm.com> References: <20121106195026.6941.24662.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit x-cbid: 12110619-5564-0000-0000-000005365356 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4171 Lines: 124 Given a page, we would like to have an efficient mechanism to find out the node memory region and the zone memory region to which it belongs. Since the node is assumed to be divided into equal-sized node memory regions, the node memory region index can be obtained by simply right-shifting the page's pfn by 'mem_region_shift'. But finding the corresponding zone memory region's index in the zone is not that straight-forward. To have a O(1) algorithm to find it out, define a zone_region_idx[] array to store the zone memory region indices for every node memory region. To illustrate, consider the following example: |<---------------------Node---------------------->| _________________________________________________ | Node mem reg 0 | Node mem reg 1 | |_______________________|_________________________| _________________________________________________ | ZONE_DMA | ZONE_NORMAL | |_______________|_________________________________| In the above figure, Node mem region 0: ------------------ This region corresponds to the first zone mem region in ZONE_DMA and also the first zone mem region in ZONE_NORMAL. Hence its index array would look like this: node_regions[0].zone_region_idx[ZONE_DMA] == 0 node_regions[0].zone_region_idx[ZONE_NORMAL] == 0 Node mem region 1: ------------------ This region corresponds to the second zone mem region in ZONE_NORMAL. Hence its index array would look like this: node_regions[1].zone_region_idx[ZONE_NORMAL] == 1 Using this index array, we can quickly obtain the zone memory region to which a given page belongs. Signed-off-by: Srivatsa S. Bhat --- include/linux/mm.h | 23 +++++++++++++++++++++++ include/linux/mmzone.h | 7 +++++++ mm/page_alloc.c | 2 ++ 3 files changed, 32 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 19c4fb0..a817b16 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -702,6 +702,29 @@ static inline struct zone *page_zone(const struct page *page) return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]; } +static inline int page_node_region_id(const struct page *page) +{ + return page_to_pfn(page) >> MEM_REGION_SHIFT; +} + +/** + * Return the index of the region to which the page belongs, within its zone. + * + * Given a page, find the absolute (node) region as well as the zone to which + * it belongs. Then find the region within the zone that corresponds to that + * absolute (node) region, and return its index. + */ +static inline int page_zone_region_id(const struct page *page) +{ + pg_data_t *pgdat = NODE_DATA(page_to_nid(page)); + enum zone_type z_num = page_zonenum(page); + unsigned long node_region_idx; + + node_region_idx = page_node_region_id(page); + + return pgdat->node_regions[node_region_idx].zone_region_idx[z_num]; +} + #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) static inline void set_page_section(struct page *page, unsigned long section) { diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 9f923aa..3982354 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -336,6 +336,13 @@ struct node_mem_region { unsigned long spanned_pages; int idx; int node; + + /* + * A physical (node) region could be split across multiple zones. + * Store the indices of the corresponding regions of each such + * zone for this physical (node) region. + */ + int zone_region_idx[MAX_NR_ZONES]; struct pglist_data *pgdat; }; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c00f72d..7fd89cd 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4621,6 +4621,8 @@ void init_zone_memory_regions(struct pglist_data *pgdat) end_pfn); z->zone_mem_region[idx].present_pages = end_pfn - start_pfn - absent; + + region->zone_region_idx[zone_idx(z)] = idx; idx++; } -- 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/