[PATCH] optional ZONE_DMA: optional ZONE_DMA in the VM
Make ZONE_DMA optional in core code.
- ifdef all code for ZONE_DMA and related definitions following the example
for ZONE_DMA32 and ZONE_HIGHMEM.
- Without ZONE_DMA, ZONE_HIGHMEM and ZONE_DMA32 we get to a ZONES_SHIFT of
0.
- Modify the VM statistics to work correctly without a DMA zone.
- Modify slab to not create DMA slabs if there is no ZONE_DMA.
[akpm@osdl.org: cleanup]
[jdike@addtoit.com: build fix]
[apw@shadowen.org: Simplify calculation of the number of bits we need for ZONES_SHIFT]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 398f2ec..ee9e314 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -96,6 +96,7 @@
#endif
enum zone_type {
+#ifdef CONFIG_ZONE_DMA
/*
* ZONE_DMA is used when there are devices that are not able
* to do DMA to all of addressable memory (ZONE_NORMAL). Then we
@@ -116,6 +117,7 @@
* <16M.
*/
ZONE_DMA,
+#endif
#ifdef CONFIG_ZONE_DMA32
/*
* x86_64 needs two ZONE_DMAs because it supports devices that are
@@ -152,11 +154,27 @@
* match the requested limits. See gfp_zone() in include/linux/gfp.h
*/
-#if !defined(CONFIG_ZONE_DMA32) && !defined(CONFIG_HIGHMEM)
+/*
+ * Count the active zones. Note that the use of defined(X) outside
+ * #if and family is not necessarily defined so ensure we cannot use
+ * it later. Use __ZONE_COUNT to work out how many shift bits we need.
+ */
+#define __ZONE_COUNT ( \
+ defined(CONFIG_ZONE_DMA) \
+ + defined(CONFIG_ZONE_DMA32) \
+ + 1 \
+ + defined(CONFIG_HIGHMEM) \
+)
+#if __ZONE_COUNT < 2
+#define ZONES_SHIFT 0
+#elif __ZONE_COUNT <= 2
#define ZONES_SHIFT 1
-#else
+#elif __ZONE_COUNT <= 4
#define ZONES_SHIFT 2
+#else
+#error ZONES_SHIFT -- too many zones configured adjust calculation
#endif
+#undef __ZONE_COUNT
struct zone {
/* Fields commonly accessed by the page allocator */
@@ -523,7 +541,11 @@
static inline int is_dma(struct zone *zone)
{
+#ifdef CONFIG_ZONE_DMA
return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
+#else
+ return 0;
+#endif
}
/* These two functions are used to setup the per zone pages min values */
