[PATCH 07/11] Use enum to define zones, reformat and comment
From: Christoph Lameter
Date: Fri Jul 07 2006 - 19:21:53 EST
Use enum for zones and reformat zones dependent information
Add comments explaning the use of zones and add a zones_t type for
zone numbers.
Line up information that will be #ifdefd by the following patches.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Index: linux-2.6.17-mm6/include/linux/mmzone.h
===================================================================
--- linux-2.6.17-mm6.orig/include/linux/mmzone.h 2006-07-03 13:47:21.738209377 -0700
+++ linux-2.6.17-mm6/include/linux/mmzone.h 2006-07-07 15:07:44.652861225 -0700
@@ -87,14 +87,53 @@ struct per_cpu_pageset {
#define zone_pcp(__z, __cpu) (&(__z)->pageset[(__cpu)])
#endif
-#define ZONE_DMA 0
-#define ZONE_DMA32 1
-#define ZONE_NORMAL 2
-#define ZONE_HIGHMEM 3
+typedef enum {
+ /*
+ * ZONE_DMA is used when there are devices that are not able
+ * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
+ * carve out the portion of memory that is needed for these devices.
+ * The range is arch specific.
+ *
+ * Some examples
+ *
+ * Architecture Limit
+ * ---------------------------
+ * parisc, ia64, sparc <4G
+ * s390 <2G
+ * arm26 <48M
+ * arm Various
+ * alpha Unlimited or 0-16MB.
+ *
+ * i386, x86_64 and multiple other arches
+ * <16M.
+ */
+ ZONE_DMA,
+ /*
+ * x86_64 needs two ZONE_DMAs because it supports devices that are
+ * only able to do DMA to the lower 16M but also 32 bit devices that
+ * can only do DMA areas below 4G.
+ */
+ ZONE_DMA32,
+ /*
+ * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
+ * performed on pages in ZONE_NORMAL if the DMA devices support
+ * transfers to all addressable memory.
+ */
+ ZONE_NORMAL,
+ /*
+ * A memory area that is only addressable by the kernel through
+ * mapping portions into its own address space. This is for example
+ * used by i386 to allow the kernel to address the memory beyond
+ * 900MB. The kernel will set up special mappings (page
+ * table entries on i386) for each page that the kernel needs to
+ * access.
+ */
+ ZONE_HIGHMEM,
-#define MAX_NR_ZONES 4 /* Sync this with ZONES_SHIFT */
-#define ZONES_SHIFT 2 /* ceil(log2(MAX_NR_ZONES)) */
+ MAX_NR_ZONES
+} zones_t;
+#define ZONES_SHIFT 2 /* ceil(log2(MAX_NR_ZONES)) */
/*
* When a memory allocation must conform to specific limitations (such
@@ -125,16 +164,6 @@ struct per_cpu_pageset {
/* #define GFP_ZONETYPES (GFP_ZONEMASK + 1) */ /* Non-loner */
#define GFP_ZONETYPES ((GFP_ZONEMASK + 1) / 2 + 1) /* Loner */
-/*
- * On machines where it is needed (eg PCs) we divide physical memory
- * into multiple physical zones. On a 32bit PC we have 4 zones:
- *
- * ZONE_DMA < 16 MB ISA DMA capable memory
- * ZONE_DMA32 0 MB Empty
- * ZONE_NORMAL 16-896 MB direct mapped by the kernel
- * ZONE_HIGHMEM > 896 MB only page cache and user processes
- */
-
struct zone {
/* Fields commonly accessed by the page allocator */
unsigned long free_pages;
@@ -270,7 +299,6 @@ struct zone {
char *name;
} ____cacheline_internodealigned_in_smp;
-
/*
* The "priority" of VM scanning is how much of the queues we will scan in one
* go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
@@ -378,12 +406,12 @@ static inline int populated_zone(struct
return (!!zone->present_pages);
}
-static inline int is_highmem_idx(int idx)
+static inline int is_highmem_idx(zones_t idx)
{
return (idx == ZONE_HIGHMEM);
}
-static inline int is_normal_idx(int idx)
+static inline int is_normal_idx(zones_t idx)
{
return (idx == ZONE_NORMAL);
}
Index: linux-2.6.17-mm6/mm/page_alloc.c
===================================================================
--- linux-2.6.17-mm6.orig/mm/page_alloc.c 2006-07-07 15:07:41.676482357 -0700
+++ linux-2.6.17-mm6/mm/page_alloc.c 2006-07-07 15:07:44.654814230 -0700
@@ -68,7 +68,11 @@ static void __free_pages_ok(struct page
* TBD: should special case ZONE_DMA32 machines here - in those we normally
* don't need any ZONE_NORMAL reservation
*/
-int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = { 256, 256, 32 };
+int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
+ 256,
+ 256,
+ 32
+};
EXPORT_SYMBOL(totalram_pages);
@@ -79,7 +83,13 @@ EXPORT_SYMBOL(totalram_pages);
struct zone *zone_table[1 << ZONETABLE_SHIFT] __read_mostly;
EXPORT_SYMBOL(zone_table);
-static char *zone_names[MAX_NR_ZONES] = { "DMA", "DMA32", "Normal", "HighMem" };
+static char *zone_names[MAX_NR_ZONES] = {
+ "DMA",
+ "DMA32",
+ "Normal",
+ "HighMem"
+};
+
int min_free_kbytes = 1024;
unsigned long __meminitdata nr_kernel_pages;
@@ -1585,7 +1595,8 @@ static void __meminit build_zonelists(pg
static void __meminit build_zonelists(pg_data_t *pgdat)
{
- int i, j, k, node, local_node;
+ int i, node, local_node;
+ zones_t k,j;
local_node = pgdat->node_id;
for (i = 0; i < GFP_ZONETYPES; i++) {
@@ -1776,8 +1787,8 @@ void zone_init_free_lists(struct pglist_
}
#define ZONETABLE_INDEX(x, zone_nr) ((x << ZONES_SHIFT) | zone_nr)
-void zonetable_add(struct zone *zone, int nid, int zid, unsigned long pfn,
- unsigned long size)
+void zonetable_add(struct zone *zone, int nid, zones_t zid,
+ unsigned long pfn, unsigned long size)
{
unsigned long snum = pfn_to_section_nr(pfn);
unsigned long end = pfn_to_section_nr(pfn + size);
@@ -2059,7 +2070,7 @@ __meminit int init_currently_empty_zone(
static void __meminit free_area_init_core(struct pglist_data *pgdat,
unsigned long *zones_size, unsigned long *zholes_size)
{
- unsigned long j;
+ zones_t j;
int nid = pgdat->node_id;
unsigned long zone_start_pfn = pgdat->node_start_pfn;
int ret;
Index: linux-2.6.17-mm6/include/linux/mm.h
===================================================================
--- linux-2.6.17-mm6.orig/include/linux/mm.h 2006-07-05 23:32:04.193233853 -0700
+++ linux-2.6.17-mm6/include/linux/mm.h 2006-07-07 15:07:44.661649745 -0700
@@ -474,7 +474,7 @@ void split_page(struct page *page, unsig
#define SECTIONS_MASK ((1UL << SECTIONS_WIDTH) - 1)
#define ZONETABLE_MASK ((1UL << ZONETABLE_SHIFT) - 1)
-static inline unsigned long page_zonenum(struct page *page)
+static inline zones_t page_zonenum(struct page *page)
{
return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
}
@@ -503,11 +503,12 @@ static inline unsigned long page_to_sect
return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
}
-static inline void set_page_zone(struct page *page, unsigned long zone)
+static inline void set_page_zone(struct page *page, zones_t 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);
@@ -519,7 +520,7 @@ static inline void set_page_section(stru
page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
}
-static inline void set_page_links(struct page *page, unsigned long zone,
+static inline void set_page_links(struct page *page, zones_t zone,
unsigned long node, unsigned long pfn)
{
set_page_zone(page, zone);
-
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