Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753435Ab0LVNrj (ORCPT ); Wed, 22 Dec 2010 08:47:39 -0500 Received: from ganesha.gnumonks.org ([213.95.27.120]:35147 "EHLO ganesha.gnumonks.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752901Ab0LVNrh (ORCPT ); Wed, 22 Dec 2010 08:47:37 -0500 From: KyongHo Cho To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: kgene.kim@samsung.com, Ilho Lee , KyongHo Cho Subject: [PATCH] mm: simple approach to calculate combined index of adjacent buddy lists Date: Wed, 22 Dec 2010 22:26:52 +0900 Message-Id: <1293024412-15617-1-git-send-email-pullip.cho@samsung.com> X-Mailer: git-send-email 1.6.2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3003 Lines: 90 The previous approach of calucation of combined index was page_idx & ~(1 << order)) but we have same result with page_idx & buddy_idx . I think this reduces instructions slightly as well as enhances readability. Signed-off-by: KyongHo Cho --- mm/page_alloc.c | 25 ++++++++++--------------- 1 files changed, 10 insertions(+), 15 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f12ad18..6033053 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -420,18 +420,10 @@ static inline void rmv_page_order(struct page *page) * * Assumption: *_mem_map is contiguous at least up to MAX_ORDER */ -static inline struct page * -__page_find_buddy(struct page *page, unsigned long page_idx, unsigned int order) -{ - unsigned long buddy_idx = page_idx ^ (1 << order); - - return page + (buddy_idx - page_idx); -} - static inline unsigned long -__find_combined_index(unsigned long page_idx, unsigned int order) +__find_buddy_index(unsigned long page_idx, unsigned int order) { - return (page_idx & ~(1 << order)); + return (page_idx ^ (1 << order)); } /* @@ -493,6 +485,7 @@ static inline void __free_one_page(struct page *page, { unsigned long page_idx; unsigned long combined_idx; + unsigned long buddy_idx; struct page *buddy; if (unlikely(PageCompound(page))) @@ -507,7 +500,8 @@ static inline void __free_one_page(struct page *page, VM_BUG_ON(bad_range(zone, page)); while (order < MAX_ORDER-1) { - buddy = __page_find_buddy(page, page_idx, order); + buddy_idx = __find_buddy_index(page_idx, order); + buddy = page + (buddy_idx - page_idx); if (!page_is_buddy(page, buddy, order)) break; @@ -515,7 +509,7 @@ static inline void __free_one_page(struct page *page, list_del(&buddy->lru); zone->free_area[order].nr_free--; rmv_page_order(buddy); - combined_idx = __find_combined_index(page_idx, order); + combined_idx = buddy_idx & page_idx; page = page + (combined_idx - page_idx); page_idx = combined_idx; order++; @@ -532,9 +526,10 @@ static inline void __free_one_page(struct page *page, */ if ((order < MAX_ORDER-1) && pfn_valid_within(page_to_pfn(buddy))) { struct page *higher_page, *higher_buddy; - combined_idx = __find_combined_index(page_idx, order); - higher_page = page + combined_idx - page_idx; - higher_buddy = __page_find_buddy(higher_page, combined_idx, order + 1); + combined_idx = buddy_idx & page_idx; + higher_page = page + (combined_idx - page_idx); + buddy_idx = __find_buddy_index(combined_idx, order + 1); + higher_buddy = page + (buddy_idx - combined_idx); if (page_is_buddy(higher_page, higher_buddy, order + 1)) { list_add_tail(&page->lru, &zone->free_area[order].free_list[migratetype]); -- 1.6.2.5 -- 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/