From b969c4ab9f182a6e1b2a0848be349f99714947b0 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 12 Jan 2012 17:19:34 -0800 Subject: mm: compaction: determine if dirty pages can be migrated without blocking within ->migratepage Asynchronous compaction is used when allocating transparent hugepages to avoid blocking for long periods of time. Due to reports of stalling, there was a debate on disabling synchronous compaction but this severely impacted allocation success rates. Part of the reason was that many dirty pages are skipped in asynchronous compaction by the following check; if (PageDirty(page) && !sync && mapping->a_ops->migratepage != migrate_page) rc = -EBUSY; This skips over all mapping aops using buffer_migrate_page() even though it is possible to migrate some of these pages without blocking. This patch updates the ->migratepage callback with a "sync" parameter. It is the responsibility of the callback to fail gracefully if migration would block. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/migrate.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/migrate.h') diff --git a/include/linux/migrate.h b/include/linux/migrate.h index e39aeecfe9a2..14e6d2a88475 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -11,7 +11,7 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **); extern void putback_lru_pages(struct list_head *l); extern int migrate_page(struct address_space *, - struct page *, struct page *); + struct page *, struct page *, bool); extern int migrate_pages(struct list_head *l, new_page_t x, unsigned long private, bool offlining, bool sync); -- cgit v1.2.3 From a6bc32b899223a877f595ef9ddc1e89ead5072b8 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 12 Jan 2012 17:19:43 -0800 Subject: mm: compaction: introduce sync-light migration for use by compaction This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT mode that avoids writing back pages to backing storage. Async compaction maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT. For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is used. This avoids sync compaction stalling for an excessive length of time, particularly when copying files to a USB stick where there might be a large number of dirty pages backed by a filesystem that does not support ->writepages. [aarcange@redhat.com: This patch is heavily based on Andrea's work] [akpm@linux-foundation.org: fix fs/nfs/write.c build] [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build] Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/migrate.h | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'include/linux/migrate.h') diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 14e6d2a88475..eaf867412f7a 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -6,18 +6,31 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **); +/* + * MIGRATE_ASYNC means never block + * MIGRATE_SYNC_LIGHT in the current implementation means to allow blocking + * on most operations but not ->writepage as the potential stall time + * is too significant + * MIGRATE_SYNC will block when migrating pages + */ +enum migrate_mode { + MIGRATE_ASYNC, + MIGRATE_SYNC_LIGHT, + MIGRATE_SYNC, +}; + #ifdef CONFIG_MIGRATION #define PAGE_MIGRATION 1 extern void putback_lru_pages(struct list_head *l); extern int migrate_page(struct address_space *, - struct page *, struct page *, bool); + struct page *, struct page *, enum migrate_mode); extern int migrate_pages(struct list_head *l, new_page_t x, unsigned long private, bool offlining, - bool sync); + enum migrate_mode mode); extern int migrate_huge_pages(struct list_head *l, new_page_t x, unsigned long private, bool offlining, - bool sync); + enum migrate_mode mode); extern int fail_migrate_page(struct address_space *, struct page *, struct page *); @@ -36,10 +49,10 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping, static inline void putback_lru_pages(struct list_head *l) {} static inline int migrate_pages(struct list_head *l, new_page_t x, unsigned long private, bool offlining, - bool sync) { return -ENOSYS; } + enum migrate_mode mode) { return -ENOSYS; } static inline int migrate_huge_pages(struct list_head *l, new_page_t x, unsigned long private, bool offlining, - bool sync) { return -ENOSYS; } + enum migrate_mode mode) { return -ENOSYS; } static inline int migrate_prep(void) { return -ENOSYS; } static inline int migrate_prep_local(void) { return -ENOSYS; } -- cgit v1.2.3 From 6536e3123e5d3371a6f52e32a3d0694bcc987702 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 20 Jan 2012 14:33:53 -0800 Subject: mm: fix warnings regarding enum migrate_mode sparc64 allmodconfig: In file included from include/linux/compat.h:15, from /usr/src/25/arch/sparc/include/asm/siginfo.h:19, from include/linux/signal.h:5, from include/linux/sched.h:73, from arch/sparc/kernel/asm-offsets.c:13: include/linux/fs.h:618: warning: parameter has incomplete type It seems that my sparc64 compiler (gcc-3.4.5) doesn't like the forward declaration of enums. Fix this by moving the "enum migrate_mode" definition into its own header file. Acked-by: Mel Gorman Cc: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/migrate.h | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) (limited to 'include/linux/migrate.h') diff --git a/include/linux/migrate.h b/include/linux/migrate.h index eaf867412f7a..05ed2828a553 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -3,22 +3,10 @@ #include #include +#include typedef struct page *new_page_t(struct page *, unsigned long private, int **); -/* - * MIGRATE_ASYNC means never block - * MIGRATE_SYNC_LIGHT in the current implementation means to allow blocking - * on most operations but not ->writepage as the potential stall time - * is too significant - * MIGRATE_SYNC will block when migrating pages - */ -enum migrate_mode { - MIGRATE_ASYNC, - MIGRATE_SYNC_LIGHT, - MIGRATE_SYNC, -}; - #ifdef CONFIG_MIGRATION #define PAGE_MIGRATION 1 -- cgit v1.2.3