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authorDave Hansen <haveblue@us.ibm.com>2005-06-23 00:07:40 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-23 09:45:01 -0700
commit348f8b6c4837a07304d2f72b11ce8d96588065e0 (patch)
treef4c6c332b2c327630b284598325dff2f44e6c9cf
parent6f167ec721108c9282d54424516a12c805e3c306 (diff)
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[PATCH] sparsemem base: reorganize page->flags bit operations
Generify the value fields in the page_flags. The aim is to allow the location and size of these fields to be varied. Additionally we want to move away from fixed allocations per field whilst still enforcing the overall bit utilisation limits. We rely on the compiler to spot and optimise the accessor functions. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/linux/mm.h53
-rw-r--r--include/linux/mmzone.h19
-rw-r--r--mm/page_alloc.c2
3 files changed, 52 insertions, 22 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1813b162b0a..57b2ead51db 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -395,19 +395,41 @@ static inline void put_page(struct page *page)
/*
* The zone field is never updated after free_area_init_core()
* sets it, so none of the operations on it need to be atomic.
- * We'll have up to (MAX_NUMNODES * MAX_NR_ZONES) zones total,
- * so we use (MAX_NODES_SHIFT + MAX_ZONES_SHIFT) here to get enough bits.
*/
-#define NODEZONE_SHIFT (sizeof(page_flags_t)*8 - MAX_NODES_SHIFT - MAX_ZONES_SHIFT)
+
+/* Page flags: | NODE | ZONE | ... | FLAGS | */
+#define NODES_PGOFF ((sizeof(page_flags_t)*8) - NODES_SHIFT)
+#define ZONES_PGOFF (NODES_PGOFF - ZONES_SHIFT)
+
+/*
+ * Define the bit shifts to access each section. For non-existant
+ * sections we define the shift as 0; that plus a 0 mask ensures
+ * the compiler will optimise away reference to them.
+ */
+#define NODES_PGSHIFT (NODES_PGOFF * (NODES_SHIFT != 0))
+#define ZONES_PGSHIFT (ZONES_PGOFF * (ZONES_SHIFT != 0))
+
+/* NODE:ZONE is used to lookup the zone from a page. */
+#define ZONETABLE_SHIFT (NODES_SHIFT + ZONES_SHIFT)
+#define ZONETABLE_PGSHIFT ZONES_PGSHIFT
+
+#if NODES_SHIFT+ZONES_SHIFT > FLAGS_RESERVED
+#error NODES_SHIFT+ZONES_SHIFT > FLAGS_RESERVED
+#endif
+
#define NODEZONE(node, zone) ((node << ZONES_SHIFT) | zone)
+#define ZONES_MASK ((1UL << ZONES_SHIFT) - 1)
+#define NODES_MASK ((1UL << NODES_SHIFT) - 1)
+#define ZONETABLE_MASK ((1UL << ZONETABLE_SHIFT) - 1)
+
static inline unsigned long page_zonenum(struct page *page)
{
- return (page->flags >> NODEZONE_SHIFT) & (~(~0UL << ZONES_SHIFT));
+ return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
}
static inline unsigned long page_to_nid(struct page *page)
{
- return (page->flags >> (NODEZONE_SHIFT + ZONES_SHIFT));
+ return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
}
struct zone;
@@ -415,13 +437,26 @@ extern struct zone *zone_table[];
static inline struct zone *page_zone(struct page *page)
{
- return zone_table[page->flags >> NODEZONE_SHIFT];
+ return zone_table[(page->flags >> ZONETABLE_PGSHIFT) &
+ ZONETABLE_MASK];
+}
+
+static inline void set_page_zone(struct page *page, unsigned long zone)
+{
+ page->flags &= ~(ZONES_MASK << ZONES_PGSHIFT);
+ page->flags |= (zone & ZONES_MASK) << ZONES_PGSHIFT;
+}
+static inline void set_page_node(struct page *page, unsigned long node)
+{
+ page->flags &= ~(NODES_MASK << NODES_PGSHIFT);
+ page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;
}
-static inline void set_page_zone(struct page *page, unsigned long nodezone_num)
+static inline void set_page_links(struct page *page, unsigned long zone,
+ unsigned long node)
{
- page->flags &= ~(~0UL << NODEZONE_SHIFT);
- page->flags |= nodezone_num << NODEZONE_SHIFT;
+ set_page_zone(page, zone);
+ set_page_node(page, node);
}
#ifndef CONFIG_DISCONTIGMEM
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index b79633d3a97..39e912708e2 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -414,30 +414,25 @@ extern struct pglist_data contig_page_data;
#include <asm/mmzone.h>
+#endif /* !CONFIG_DISCONTIGMEM */
+
#if BITS_PER_LONG == 32 || defined(ARCH_HAS_ATOMIC_UNSIGNED)
/*
* with 32 bit page->flags field, we reserve 8 bits for node/zone info.
* there are 3 zones (2 bits) and this leaves 8-2=6 bits for nodes.
*/
-#define MAX_NODES_SHIFT 6
+#define FLAGS_RESERVED 8
+
#elif BITS_PER_LONG == 64
/*
* with 64 bit flags field, there's plenty of room.
*/
-#define MAX_NODES_SHIFT 10
-#endif
+#define FLAGS_RESERVED 32
-#endif /* !CONFIG_DISCONTIGMEM */
-
-#if NODES_SHIFT > MAX_NODES_SHIFT
-#error NODES_SHIFT > MAX_NODES_SHIFT
-#endif
+#else
-/* There are currently 3 zones: DMA, Normal & Highmem, thus we need 2 bits */
-#define MAX_ZONES_SHIFT 2
+#error BITS_PER_LONG not defined
-#if ZONES_SHIFT > MAX_ZONES_SHIFT
-#error ZONES_SHIFT > MAX_ZONES_SHIFT
#endif
#endif /* !__ASSEMBLY__ */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bf1dd881909..1958358e29b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1653,7 +1653,7 @@ void __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
struct page *page;
for (page = start; page < (start + size); page++) {
- set_page_zone(page, NODEZONE(nid, zone));
+ set_page_links(page, zone, nid);
set_page_count(page, 0);
reset_page_mapcount(page);
SetPageReserved(page);