Print out statistics in relation to fragmentation avoidance to /proc/pagetypeinfo

This patch provides fragmentation avoidance statistics via /proc/pagetypeinfo.
 The information is collected only on request so there is no runtime overhead.
 The statistics are in three parts:

The first part prints information on the size of blocks that pages are
being grouped on and looks like

Page block order: 10
Pages per block:  1024

The second part is a more detailed version of /proc/buddyinfo and looks like

Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
Node    0, zone      DMA, type    Unmovable      0      0      0      0      0      0      0      0      0      0      0
Node    0, zone      DMA, type  Reclaimable      1      0      0      0      0      0      0      0      0      0      0
Node    0, zone      DMA, type      Movable      0      0      0      0      0      0      0      0      0      0      0
Node    0, zone      DMA, type      Reserve      0      4      4      0      0      0      0      1      0      1      0
Node    0, zone   Normal, type    Unmovable    111      8      4      4      2      3      1      0      0      0      0
Node    0, zone   Normal, type  Reclaimable    293     89      8      0      0      0      0      0      0      0      0
Node    0, zone   Normal, type      Movable      1      6     13      9      7      6      3      0      0      0      0
Node    0, zone   Normal, type      Reserve      0      0      0      0      0      0      0      0      0      0      4

The third part looks like

Number of blocks type     Unmovable  Reclaimable      Movable      Reserve
Node 0, zone      DMA            0            1            2            1
Node 0, zone   Normal            3           17           94            4

To walk the zones within a node with interrupts disabled, walk_zones_in_node()
is introduced and shared between /proc/buddyinfo, /proc/zoneinfo and
/proc/pagetypeinfo to reduce code duplication.  It seems specific to what
vmstat.c requires but could be broken out as a general utility function in
mmzone.c if there were other other potential users.

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

2 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index f8ffcd401c5f..7e93a9ae7064 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -104,6 +104,18 @@ struct vm_area_struct;
 /* 4GB DMA on some platforms */
 #define GFP_DMA32       __GFP_DMA32
 
+/* Convert GFP flags to their corresponding migrate type */
+static inline int allocflags_to_migratetype(gfp_t gfp_flags)
+{
+        WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+
+        if (unlikely(page_group_by_mobility_disabled))
+                return MIGRATE_UNMOVABLE;
+
+        /* Group based on mobility */
+        return (((gfp_flags & __GFP_MOVABLE) != 0) << 1) |
+                ((gfp_flags & __GFP_RECLAIMABLE) != 0);
+}
 
 static inline enum zone_type gfp_zone(gfp_t flags)
 {
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 87a4045580f2..20ea42c45e4a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -43,6 +43,16 @@
         for (order = 0; order < MAX_ORDER; order++) \
                 for (type = 0; type < MIGRATE_TYPES; type++)
 
+extern int page_group_by_mobility_disabled;
+
+static inline int get_pageblock_migratetype(struct page *page)
+{
+        if (unlikely(page_group_by_mobility_disabled))
+                return MIGRATE_UNMOVABLE;
+
+        return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end);
+}
+
 struct free_area {
         struct list_head        free_list[MIGRATE_TYPES];
         unsigned long           nr_free;