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, 12 insertions, 3 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index da8aa872eb6e..f8ffcd401c5f 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -48,9 +48,10 @@ struct vm_area_struct;
 #define __GFP_NOMEMALLOC ((__force gfp_t)0x10000u) /* Don't use emergency reserves */
 #define __GFP_HARDWALL   ((__force gfp_t)0x20000u) /* Enforce hardwall cpuset memory allocs */
 #define __GFP_THISNODE  ((__force gfp_t)0x40000u)/* No fallback, no policies */
-#define __GFP_MOVABLE   ((__force gfp_t)0x80000u) /* Page is movable */
+#define __GFP_RECLAIMABLE ((__force gfp_t)0x80000u) /* Page is reclaimable */
+#define __GFP_MOVABLE   ((__force gfp_t)0x100000u)  /* Page is movable */
 
-#define __GFP_BITS_SHIFT 20     /* Room for 20 __GFP_FOO bits */
+#define __GFP_BITS_SHIFT 21     /* Room for 21 __GFP_FOO bits */
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /* This equals 0, but use constants in case they ever change */
@@ -60,6 +61,8 @@ struct vm_area_struct;
 #define GFP_NOIO        (__GFP_WAIT)
 #define GFP_NOFS        (__GFP_WAIT | __GFP_IO)
 #define GFP_KERNEL      (__GFP_WAIT | __GFP_IO | __GFP_FS)
+#define GFP_TEMPORARY   (__GFP_WAIT | __GFP_IO | __GFP_FS | \
+                         __GFP_RECLAIMABLE)
 #define GFP_USER        (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL)
 #define GFP_HIGHUSER    (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL | \
                          __GFP_HIGHMEM)
@@ -80,7 +83,7 @@ struct vm_area_struct;
 #endif
 
 /* This mask makes up all the page movable related flags */
-#define GFP_MOVABLE_MASK (__GFP_MOVABLE)
+#define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
 
 /* Control page allocator reclaim behavior */
 #define GFP_RECLAIM_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS|\
@@ -129,6 +132,12 @@ static inline enum zone_type gfp_zone(gfp_t flags)
         return base + ZONE_NORMAL;
 }
 
+static inline gfp_t set_migrateflags(gfp_t gfp, gfp_t migrate_flags)
+{
+        BUG_ON((gfp & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+        return (gfp & ~(GFP_MOVABLE_MASK)) | migrate_flags;
+}
+
 /*
  * There is only one page-allocator function, and two main namespaces to
  * it. The alloc_page*() variants return 'struct page *' and as such