From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mel Gorman Message-Id: <20070618092921.7790.78151.sendpatchset@skynet.skynet.ie> In-Reply-To: <20070618092821.7790.52015.sendpatchset@skynet.skynet.ie> References: <20070618092821.7790.52015.sendpatchset@skynet.skynet.ie> Subject: [PATCH 3/7] Introduce isolate_lru_page_nolock() as a lockless version of isolate_lru_page() Date: Mon, 18 Jun 2007 10:29:21 +0100 (IST) Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Mel Gorman , kamezawa.hiroyu@jp.fujitsu.com, clameter@sgi.com List-ID: Migration uses isolate_lru_page() to isolate an LRU page. This acquires the zone->lru_lock to safely remove the page and place it on a private list. However, this prevents the caller from batching up isolation of multiple pages. This patch introduces a nolock version of isolate_lru_page() for callers that are aware of the locking requirements. Signed-off-by: Mel Gorman Acked-by: Andy Whitcroft --- include/linux/migrate.h | 8 +++++++- mm/migrate.c | 36 +++++++++++++++++++++++++++--------- 2 files changed, 34 insertions(+), 10 deletions(-) diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc4-mm2-015_migration_flatmem/include/linux/migrate.h linux-2.6.22-rc4-mm2-020_isolate_nolock/include/linux/migrate.h --- linux-2.6.22-rc4-mm2-015_migration_flatmem/include/linux/migrate.h 2007-06-15 16:25:37.000000000 +0100 +++ linux-2.6.22-rc4-mm2-020_isolate_nolock/include/linux/migrate.h 2007-06-15 16:25:46.000000000 +0100 @@ -27,6 +27,8 @@ static inline int vma_migratable(struct #endif #ifdef CONFIG_MIGRATION +extern int locked_isolate_lru_page(struct zone *zone, struct page *p, + struct list_head *pagelist); extern int isolate_lru_page(struct page *p, struct list_head *pagelist); extern int putback_lru_pages(struct list_head *l); extern int migrate_page(struct address_space *, @@ -41,7 +43,11 @@ extern int migrate_vmas(struct mm_struct const nodemask_t *from, const nodemask_t *to, unsigned long flags); #else - +static inline int locked_isolate_lru_page(struct zone *zone, struct page *p, + struct list_head *list) +{ + return -ENOSYS; +} static inline int isolate_lru_page(struct page *p, struct list_head *list) { return -ENOSYS; } static inline int putback_lru_pages(struct list_head *l) { return 0; } diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc4-mm2-015_migration_flatmem/mm/migrate.c linux-2.6.22-rc4-mm2-020_isolate_nolock/mm/migrate.c --- linux-2.6.22-rc4-mm2-015_migration_flatmem/mm/migrate.c 2007-06-15 16:25:31.000000000 +0100 +++ linux-2.6.22-rc4-mm2-020_isolate_nolock/mm/migrate.c 2007-06-15 16:25:46.000000000 +0100 @@ -41,6 +41,32 @@ * -EBUSY: page not on LRU list * 0: page removed from LRU list and added to the specified list. */ +int locked_isolate_lru_page(struct zone *zone, struct page *page, + struct list_head *pagelist) +{ + int ret = -EBUSY; + + if (PageLRU(page) && get_page_unless_zero(page)) { + ret = 0; + ClearPageLRU(page); + if (PageActive(page)) + del_page_from_active_list(zone, page); + else + del_page_from_inactive_list(zone, page); + list_add_tail(&page->lru, pagelist); + } + + return ret; +} + +/* + * Acquire the zone->lru_lock and isolate one page from the LRU lists. If + * successful put it onto the indicated list with elevated page count. + * + * Result: + * -EBUSY: page not on LRU list + * 0: page removed from LRU list and added to the specified list. + */ int isolate_lru_page(struct page *page, struct list_head *pagelist) { int ret = -EBUSY; @@ -49,15 +75,7 @@ int isolate_lru_page(struct page *page, struct zone *zone = page_zone(page); spin_lock_irq(&zone->lru_lock); - if (PageLRU(page) && get_page_unless_zero(page)) { - ret = 0; - ClearPageLRU(page); - if (PageActive(page)) - del_page_from_active_list(zone, page); - else - del_page_from_inactive_list(zone, page); - list_add_tail(&page->lru, pagelist); - } + ret = locked_isolate_lru_page(zone, page, pagelist); spin_unlock_irq(&zone->lru_lock); } return ret; -- 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