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authorMel Gorman <mgorman@suse.de>2012-01-12 17:19:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 20:13:09 -0800
commita6bc32b899223a877f595ef9ddc1e89ead5072b8 (patch)
treea9529f7af2cf8e77bb6670acea32169c891a2b76 /include/linux/migrate.h
parent66199712e9eef5aede09dbcd9dfff87798a66917 (diff)
downloadop-kernel-dev-a6bc32b899223a877f595ef9ddc1e89ead5072b8.zip
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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 <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/migrate.h')
-rw-r--r--include/linux/migrate.h23
1 files changed, 18 insertions, 5 deletions
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 14e6d2a..eaf8674 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; }
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