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mm: compaction: introduce sync-light migration for use by compaction

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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>
This commit is contained in:
Mel Gorman
2012-01-12 17:19:43 -08:00
committed by Linus Torvalds
parent 66199712e9
commit a6bc32b899
11 changed files with 76 additions and 52 deletions
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23
include/linux/migrate.h
View File

@@ -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; }