Linux kernel mirror (for testing)
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1#ifndef _LINUX_COMPACTION_H
2#define _LINUX_COMPACTION_H
3
4/* Return values for compact_zone() and try_to_compact_pages() */
5/* compaction didn't start as it was not possible or direct reclaim was more suitable */
6#define COMPACT_SKIPPED 0
7/* compaction should continue to another pageblock */
8#define COMPACT_CONTINUE 1
9/* direct compaction partially compacted a zone and there are suitable pages */
10#define COMPACT_PARTIAL 2
11/* The full zone was compacted */
12#define COMPACT_COMPLETE 3
13
14#ifdef CONFIG_COMPACTION
15extern int sysctl_compact_memory;
16extern int sysctl_compaction_handler(struct ctl_table *table, int write,
17 void __user *buffer, size_t *length, loff_t *ppos);
18extern int sysctl_extfrag_threshold;
19extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
20 void __user *buffer, size_t *length, loff_t *ppos);
21
22extern int fragmentation_index(struct zone *zone, unsigned int order);
23extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
24 int order, gfp_t gfp_mask, nodemask_t *mask,
25 bool sync, bool *contended);
26extern int compact_pgdat(pg_data_t *pgdat, int order);
27extern void reset_isolation_suitable(pg_data_t *pgdat);
28extern unsigned long compaction_suitable(struct zone *zone, int order);
29
30/* Do not skip compaction more than 64 times */
31#define COMPACT_MAX_DEFER_SHIFT 6
32
33/*
34 * Compaction is deferred when compaction fails to result in a page
35 * allocation success. 1 << compact_defer_limit compactions are skipped up
36 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
37 */
38static inline void defer_compaction(struct zone *zone, int order)
39{
40 zone->compact_considered = 0;
41 zone->compact_defer_shift++;
42
43 if (order < zone->compact_order_failed)
44 zone->compact_order_failed = order;
45
46 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
47 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
48}
49
50/* Returns true if compaction should be skipped this time */
51static inline bool compaction_deferred(struct zone *zone, int order)
52{
53 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
54
55 if (order < zone->compact_order_failed)
56 return false;
57
58 /* Avoid possible overflow */
59 if (++zone->compact_considered > defer_limit)
60 zone->compact_considered = defer_limit;
61
62 return zone->compact_considered < defer_limit;
63}
64
65/* Returns true if restarting compaction after many failures */
66static inline bool compaction_restarting(struct zone *zone, int order)
67{
68 if (order < zone->compact_order_failed)
69 return false;
70
71 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
72 zone->compact_considered >= 1UL << zone->compact_defer_shift;
73}
74
75#else
76static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
77 int order, gfp_t gfp_mask, nodemask_t *nodemask,
78 bool sync, bool *contended)
79{
80 return COMPACT_CONTINUE;
81}
82
83static inline int compact_pgdat(pg_data_t *pgdat, int order)
84{
85 return COMPACT_CONTINUE;
86}
87
88static inline void reset_isolation_suitable(pg_data_t *pgdat)
89{
90}
91
92static inline unsigned long compaction_suitable(struct zone *zone, int order)
93{
94 return COMPACT_SKIPPED;
95}
96
97static inline void defer_compaction(struct zone *zone, int order)
98{
99}
100
101static inline bool compaction_deferred(struct zone *zone, int order)
102{
103 return true;
104}
105
106#endif /* CONFIG_COMPACTION */
107
108#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
109extern int compaction_register_node(struct node *node);
110extern void compaction_unregister_node(struct node *node);
111
112#else
113
114static inline int compaction_register_node(struct node *node)
115{
116 return 0;
117}
118
119static inline void compaction_unregister_node(struct node *node)
120{
121}
122#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
123
124#endif /* _LINUX_COMPACTION_H */