Group short-lived and reclaimable kernel allocations

This patch marks a number of allocations that are either short-lived such as
network buffers or are reclaimable such as inode allocations.  When something
like updatedb is called, long-lived and unmovable kernel allocations tend to
be spread throughout the address space which increases fragmentation.

This patch groups these allocations together as much as possible by adding a
new MIGRATE_TYPE.  The MIGRATE_RECLAIMABLE type is for allocations that can be
reclaimed on demand, but not moved.  i.e.  they can be migrated by deleting
them and re-reading the information from elsewhere.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d575a3ee8dd8..29f4de1423c9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -172,7 +172,10 @@ static void set_pageblock_migratetype(struct page *page, int migratetype)
 
 static inline int gfpflags_to_migratetype(gfp_t gfp_flags)
 {
-        return ((gfp_flags & __GFP_MOVABLE) != 0);
+        WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+
+        return (((gfp_flags & __GFP_MOVABLE) != 0) << 1) |
+                ((gfp_flags & __GFP_RECLAIMABLE) != 0);
 }
 
 #else
@@ -676,8 +679,9 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
  * the free lists for the desirable migrate type are depleted
  */
 static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = {
-        [MIGRATE_UNMOVABLE] = { MIGRATE_MOVABLE   },
-        [MIGRATE_MOVABLE]   = { MIGRATE_UNMOVABLE },
+        [MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE   },
+        [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE   },
+        [MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
 };
 
 /*