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 deferred due to past failures */
6#define COMPACT_DEFERRED 0
7/* compaction didn't start as it was not possible or direct reclaim was more suitable */
8#define COMPACT_SKIPPED 1
9/* compaction should continue to another pageblock */
10#define COMPACT_CONTINUE 2
11/* direct compaction partially compacted a zone and there are suitable pages */
12#define COMPACT_PARTIAL 3
13/* The full zone was compacted */
14#define COMPACT_COMPLETE 4
15
16/* Used to signal whether compaction detected need_sched() or lock contention */
17/* No contention detected */
18#define COMPACT_CONTENDED_NONE 0
19/* Either need_sched() was true or fatal signal pending */
20#define COMPACT_CONTENDED_SCHED 1
21/* Zone lock or lru_lock was contended in async compaction */
22#define COMPACT_CONTENDED_LOCK 2
23
24#ifdef CONFIG_COMPACTION
25extern int sysctl_compact_memory;
26extern int sysctl_compaction_handler(struct ctl_table *table, int write,
27 void __user *buffer, size_t *length, loff_t *ppos);
28extern int sysctl_extfrag_threshold;
29extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
30 void __user *buffer, size_t *length, loff_t *ppos);
31
32extern int fragmentation_index(struct zone *zone, unsigned int order);
33extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
34 int order, gfp_t gfp_mask, nodemask_t *mask,
35 enum migrate_mode mode, int *contended,
36 struct zone **candidate_zone);
37extern void compact_pgdat(pg_data_t *pgdat, int order);
38extern void reset_isolation_suitable(pg_data_t *pgdat);
39extern unsigned long compaction_suitable(struct zone *zone, int order);
40
41/* Do not skip compaction more than 64 times */
42#define COMPACT_MAX_DEFER_SHIFT 6
43
44/*
45 * Compaction is deferred when compaction fails to result in a page
46 * allocation success. 1 << compact_defer_limit compactions are skipped up
47 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
48 */
49static inline void defer_compaction(struct zone *zone, int order)
50{
51 zone->compact_considered = 0;
52 zone->compact_defer_shift++;
53
54 if (order < zone->compact_order_failed)
55 zone->compact_order_failed = order;
56
57 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
58 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
59}
60
61/* Returns true if compaction should be skipped this time */
62static inline bool compaction_deferred(struct zone *zone, int order)
63{
64 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
65
66 if (order < zone->compact_order_failed)
67 return false;
68
69 /* Avoid possible overflow */
70 if (++zone->compact_considered > defer_limit)
71 zone->compact_considered = defer_limit;
72
73 return zone->compact_considered < defer_limit;
74}
75
76/*
77 * Update defer tracking counters after successful compaction of given order,
78 * which means an allocation either succeeded (alloc_success == true) or is
79 * expected to succeed.
80 */
81static inline void compaction_defer_reset(struct zone *zone, int order,
82 bool alloc_success)
83{
84 if (alloc_success) {
85 zone->compact_considered = 0;
86 zone->compact_defer_shift = 0;
87 }
88 if (order >= zone->compact_order_failed)
89 zone->compact_order_failed = order + 1;
90}
91
92/* Returns true if restarting compaction after many failures */
93static inline bool compaction_restarting(struct zone *zone, int order)
94{
95 if (order < zone->compact_order_failed)
96 return false;
97
98 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
99 zone->compact_considered >= 1UL << zone->compact_defer_shift;
100}
101
102#else
103static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
104 int order, gfp_t gfp_mask, nodemask_t *nodemask,
105 enum migrate_mode mode, int *contended,
106 struct zone **candidate_zone)
107{
108 return COMPACT_CONTINUE;
109}
110
111static inline void compact_pgdat(pg_data_t *pgdat, int order)
112{
113}
114
115static inline void reset_isolation_suitable(pg_data_t *pgdat)
116{
117}
118
119static inline unsigned long compaction_suitable(struct zone *zone, int order)
120{
121 return COMPACT_SKIPPED;
122}
123
124static inline void defer_compaction(struct zone *zone, int order)
125{
126}
127
128static inline bool compaction_deferred(struct zone *zone, int order)
129{
130 return true;
131}
132
133#endif /* CONFIG_COMPACTION */
134
135#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
136extern int compaction_register_node(struct node *node);
137extern void compaction_unregister_node(struct node *node);
138
139#else
140
141static inline int compaction_register_node(struct node *node)
142{
143 return 0;
144}
145
146static inline void compaction_unregister_node(struct node *node)
147{
148}
149#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
150
151#endif /* _LINUX_COMPACTION_H */