mm: compaction: memory compaction core
This patch is the core of a mechanism which compacts memory in a zone by
relocating movable pages towards the end of the zone.
A single compaction run involves a migration scanner and a free scanner.
Both scanners operate on pageblock-sized areas in the zone. The migration
scanner starts at the bottom of the zone and searches for all movable
pages within each area, isolating them onto a private list called
migratelist. The free scanner starts at the top of the zone and searches
for suitable areas and consumes the free pages within making them
available for the migration scanner. The pages isolated for migration are
then migrated to the newly isolated free pages.
[aarcange@redhat.com: Fix unsafe optimisation]
[mel@csn.ul.ie: do not schedule work on other CPUs for compaction]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
new file mode 100644
index 0000000..465ca88
--- /dev/null
+++ b/include/linux/compaction.h
@@ -0,0 +1,9 @@
+#ifndef _LINUX_COMPACTION_H
+#define _LINUX_COMPACTION_H
+
+/* Return values for compact_zone() */
+#define COMPACT_CONTINUE 0
+#define COMPACT_PARTIAL 1
+#define COMPACT_COMPLETE 2
+
+#endif /* _LINUX_COMPACTION_H */
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 7a07b17..7238231 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -19,6 +19,7 @@
struct page *, struct page *);
extern int migrate_prep(void);
+extern int migrate_prep_local(void);
extern int migrate_vmas(struct mm_struct *mm,
const nodemask_t *from, const nodemask_t *to,
unsigned long flags);
@@ -30,6 +31,7 @@
unsigned long private, int offlining) { return -ENOSYS; }
static inline int migrate_prep(void) { return -ENOSYS; }
+static inline int migrate_prep_local(void) { return -ENOSYS; }
static inline int migrate_vmas(struct mm_struct *mm,
const nodemask_t *from, const nodemask_t *to,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 98ea5ba..963f908a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -337,6 +337,7 @@
void put_pages_list(struct list_head *pages);
void split_page(struct page *page, unsigned int order);
+int split_free_page(struct page *page);
/*
* Compound pages have a destructor function. Provide a
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1e8ce14..b6b6143 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -152,6 +152,7 @@
};
#define SWAP_CLUSTER_MAX 32
+#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 117f0dd..b421d1b 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -43,6 +43,9 @@
KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
KSWAPD_SKIP_CONGESTION_WAIT,
PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+#ifdef CONFIG_COMPACTION
+ COMPACTBLOCKS, COMPACTPAGES, COMPACTPAGEFAILED,
+#endif
#ifdef CONFIG_HUGETLB_PAGE
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
#endif