[PATCH] linearly index zone->node_zonelists[]
I wonder why we need this bitmask indexing into zone->node_zonelists[]?
We always start with the highest zone and then include all lower zones
if we build zonelists.
Are there really cases where we need allocation from ZONE_DMA or
ZONE_HIGHMEM but not ZONE_NORMAL? It seems that the current implementation
of highest_zone() makes that already impossible.
If we go linear on the index then gfp_zone() == highest_zone() and a lot
of definitions fall by the wayside.
We can now revert back to the use of gfp_zone() in mempolicy.c ;-)
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 76d33e6..7fe3171 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -137,60 +137,18 @@
MAX_NR_ZONES
};
-
/*
* When a memory allocation must conform to specific limitations (such
* as being suitable for DMA) the caller will pass in hints to the
* allocator in the gfp_mask, in the zone modifier bits. These bits
* are used to select a priority ordered list of memory zones which
- * match the requested limits. GFP_ZONEMASK defines which bits within
- * the gfp_mask should be considered as zone modifiers. Each valid
- * combination of the zone modifier bits has a corresponding list
- * of zones (in node_zonelists). Thus for two zone modifiers there
- * will be a maximum of 4 (2 ** 2) zonelists, for 3 modifiers there will
- * be 8 (2 ** 3) zonelists. GFP_ZONETYPES defines the number of possible
- * combinations of zone modifiers in "zone modifier space".
- *
- * As an optimisation any zone modifier bits which are only valid when
- * no other zone modifier bits are set (loners) should be placed in
- * the highest order bits of this field. This allows us to reduce the
- * extent of the zonelists thus saving space. For example in the case
- * of three zone modifier bits, we could require up to eight zonelists.
- * If the left most zone modifier is a "loner" then the highest valid
- * zonelist would be four allowing us to allocate only five zonelists.
- * Use the first form for GFP_ZONETYPES when the left most bit is not
- * a "loner", otherwise use the second.
- *
- * NOTE! Make sure this matches the zones in <linux/gfp.h>
+ * match the requested limits. See gfp_zone() in include/linux/gfp.h
*/
-#ifdef CONFIG_ZONE_DMA32
-
-#ifdef CONFIG_HIGHMEM
-#define GFP_ZONETYPES ((GFP_ZONEMASK + 1) / 2 + 1) /* Loner */
-#define GFP_ZONEMASK 0x07
-#define ZONES_SHIFT 2 /* ceil(log2(MAX_NR_ZONES)) */
+#if !defined(CONFIG_ZONE_DMA32) && !defined(CONFIG_HIGHMEM)
+#define ZONES_SHIFT 1
#else
-#define GFP_ZONETYPES ((0x07 + 1) / 2 + 1) /* Loner */
-/* Mask __GFP_HIGHMEM */
-#define GFP_ZONEMASK 0x05
-#define ZONES_SHIFT 2
-#endif
-
-#else
-#ifdef CONFIG_HIGHMEM
-
-#define GFP_ZONEMASK 0x03
-#define ZONES_SHIFT 2
-#define GFP_ZONETYPES 3
-
-#else
-
-#define GFP_ZONEMASK 0x01
-#define ZONES_SHIFT 1
-#define GFP_ZONETYPES 2
-
-#endif
+#define ZONES_SHIFT 2
#endif
struct zone {
@@ -360,7 +318,7 @@
struct bootmem_data;
typedef struct pglist_data {
struct zone node_zones[MAX_NR_ZONES];
- struct zonelist node_zonelists[GFP_ZONETYPES];
+ struct zonelist node_zonelists[MAX_NR_ZONES];
int nr_zones;
#ifdef CONFIG_FLAT_NODE_MEM_MAP
struct page *node_mem_map;
