1 #ifndef _LINUX_COMPACTION_H
2 #define _LINUX_COMPACTION_H
4 #include <linux/node.h>
6 /* Return values for compact_zone() and try_to_compact_pages() */
7 /* compaction didn't start as it was not possible or direct reclaim was more suitable */
8 #define COMPACT_SKIPPED 0
9 /* compaction should continue to another pageblock */
10 #define COMPACT_CONTINUE 1
11 /* direct compaction partially compacted a zone and there are suitable pages */
12 #define COMPACT_PARTIAL 2
13 /* The full zone was compacted */
14 #define COMPACT_COMPLETE 3
17 * compaction supports three modes
19 * COMPACT_ASYNC_MOVABLE uses asynchronous migration and only scans
20 * MIGRATE_MOVABLE pageblocks as migration sources and targets.
21 * COMPACT_ASYNC_UNMOVABLE uses asynchronous migration and only scans
22 * MIGRATE_MOVABLE pageblocks as migration sources.
23 * MIGRATE_UNMOVABLE pageblocks are scanned as potential migration
24 * targets and convers them to MIGRATE_MOVABLE if possible
25 * COMPACT_SYNC uses synchronous migration and scans all pageblocks
28 COMPACT_ASYNC_MOVABLE,
29 COMPACT_ASYNC_UNMOVABLE,
33 #ifdef CONFIG_COMPACTION
34 extern int sysctl_compact_memory;
35 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
36 void __user *buffer, size_t *length, loff_t *ppos);
37 extern int sysctl_extfrag_threshold;
38 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
39 void __user *buffer, size_t *length, loff_t *ppos);
41 extern int fragmentation_index(struct zone *zone, unsigned int order);
42 extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
43 int order, gfp_t gfp_mask, nodemask_t *mask,
45 extern int compact_pgdat(pg_data_t *pgdat, int order);
46 extern unsigned long compaction_suitable(struct zone *zone, int order);
48 /* Do not skip compaction more than 64 times */
49 #define COMPACT_MAX_DEFER_SHIFT 6
52 * Compaction is deferred when compaction fails to result in a page
53 * allocation success. 1 << compact_defer_limit compactions are skipped up
54 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
56 static inline void defer_compaction(struct zone *zone, int order)
58 zone->compact_considered = 0;
59 zone->compact_defer_shift++;
61 if (order < zone->compact_order_failed)
62 zone->compact_order_failed = order;
64 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
65 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
68 /* Returns true if compaction should be skipped this time */
69 static inline bool compaction_deferred(struct zone *zone, int order)
71 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
73 if (order < zone->compact_order_failed)
76 /* Avoid possible overflow */
77 if (++zone->compact_considered > defer_limit)
78 zone->compact_considered = defer_limit;
80 return zone->compact_considered < (1UL << zone->compact_defer_shift);
84 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
85 int order, gfp_t gfp_mask, nodemask_t *nodemask,
88 return COMPACT_CONTINUE;
91 static inline int compact_pgdat(pg_data_t *pgdat, int order)
93 return COMPACT_CONTINUE;
96 static inline unsigned long compaction_suitable(struct zone *zone, int order)
98 return COMPACT_SKIPPED;
101 static inline void defer_compaction(struct zone *zone, int order)
105 static inline bool compaction_deferred(struct zone *zone, int order)
110 #endif /* CONFIG_COMPACTION */
112 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
113 extern int compaction_register_node(struct node *node);
114 extern void compaction_unregister_node(struct node *node);
118 static inline int compaction_register_node(struct node *node)
123 static inline void compaction_unregister_node(struct node *node)
126 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
128 #endif /* _LINUX_COMPACTION_H */