blob: e35bfb82c8555b7377334dbea42bfcf588b0bab8 [file] [log] [blame]
KAMEZAWA Hiroyuki95144c72006-03-27 01:16:02 -08001/*
2 * linux/mm/mmzone.c
3 *
4 * management codes for pgdats and zones.
5 */
6
7
KAMEZAWA Hiroyuki95144c72006-03-27 01:16:02 -08008#include <linux/stddef.h>
Mel Gormaneb335752009-05-13 17:34:48 +01009#include <linux/mm.h>
KAMEZAWA Hiroyuki95144c72006-03-27 01:16:02 -080010#include <linux/mmzone.h>
11#include <linux/module.h>
12
13struct pglist_data *first_online_pgdat(void)
14{
15 return NODE_DATA(first_online_node);
16}
17
KAMEZAWA Hiroyuki95144c72006-03-27 01:16:02 -080018struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
19{
20 int nid = next_online_node(pgdat->node_id);
21
22 if (nid == MAX_NUMNODES)
23 return NULL;
24 return NODE_DATA(nid);
25}
KAMEZAWA Hiroyuki95144c72006-03-27 01:16:02 -080026
27/*
28 * next_zone - helper magic for for_each_zone()
29 */
30struct zone *next_zone(struct zone *zone)
31{
32 pg_data_t *pgdat = zone->zone_pgdat;
33
34 if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
35 zone++;
36 else {
37 pgdat = next_online_pgdat(pgdat);
38 if (pgdat)
39 zone = pgdat->node_zones;
40 else
41 zone = NULL;
42 }
43 return zone;
44}
KAMEZAWA Hiroyuki95144c72006-03-27 01:16:02 -080045
Mel Gorman19770b32008-04-28 02:12:18 -070046static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
47{
48#ifdef CONFIG_NUMA
49 return node_isset(zonelist_node_idx(zref), *nodes);
50#else
51 return 1;
52#endif /* CONFIG_NUMA */
53}
54
55/* Returns the next zone at or below highest_zoneidx in a zonelist */
56struct zoneref *next_zones_zonelist(struct zoneref *z,
57 enum zone_type highest_zoneidx,
58 nodemask_t *nodes,
59 struct zone **zone)
60{
61 /*
62 * Find the next suitable zone to use for the allocation.
63 * Only filter based on nodemask if it's set
64 */
65 if (likely(nodes == NULL))
66 while (zonelist_zone_idx(z) > highest_zoneidx)
67 z++;
68 else
69 while (zonelist_zone_idx(z) > highest_zoneidx ||
70 (z->zone && !zref_in_nodemask(z, nodes)))
71 z++;
72
Mel Gorman5bead2a2008-09-13 02:33:19 -070073 *zone = zonelist_zone(z);
Mel Gorman19770b32008-04-28 02:12:18 -070074 return z;
75}
Mel Gormaneb335752009-05-13 17:34:48 +010076
77#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
78int memmap_valid_within(unsigned long pfn,
79 struct page *page, struct zone *zone)
80{
81 if (page_to_pfn(page) != pfn)
82 return 0;
83
84 if (page_zone(page) != zone)
85 return 0;
86
87 return 1;
88}
89#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
Christoph Lameteraa454842010-09-09 16:38:17 -070090
91#ifdef CONFIG_SMP
92/* Called when a more accurate view of NR_FREE_PAGES is needed */
93unsigned long zone_nr_free_pages(struct zone *zone)
94{
95 unsigned long nr_free_pages = zone_page_state(zone, NR_FREE_PAGES);
96
97 /*
98 * While kswapd is awake, it is considered the zone is under some
99 * memory pressure. Under pressure, there is a risk that
100 * per-cpu-counter-drift will allow the min watermark to be breached
101 * potentially causing a live-lock. While kswapd is awake and
102 * free pages are low, get a better estimate for free pages
103 */
104 if (nr_free_pages < zone->percpu_drift_mark &&
105 !waitqueue_active(&zone->zone_pgdat->kswapd_wait))
106 return zone_page_state_snapshot(zone, NR_FREE_PAGES);
107
108 return nr_free_pages;
109}
110#endif /* CONFIG_SMP */