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 void 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/*
66 * Update defer tracking counters after successful compaction of given order,
67 * which means an allocation either succeeded (alloc_success == true) or is
68 * expected to succeed.
69 */
70static inline void compaction_defer_reset(struct zone *zone, int order,
71 bool alloc_success)
72{
73 if (alloc_success) {
74 zone->compact_considered = 0;
75 zone->compact_defer_shift = 0;
76 }
77 if (order >= zone->compact_order_failed)
78 zone->compact_order_failed = order + 1;
79}
80
81/* Returns true if restarting compaction after many failures */
82static inline bool compaction_restarting(struct zone *zone, int order)
83{
84 if (order < zone->compact_order_failed)
85 return false;
86
87 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
88 zone->compact_considered >= 1UL << zone->compact_defer_shift;
89}
90
91#else
92static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
93 int order, gfp_t gfp_mask, nodemask_t *nodemask,
94 bool sync, bool *contended)
95{
96 return COMPACT_CONTINUE;
97}
98
99static inline void compact_pgdat(pg_data_t *pgdat, int order)
100{
101}
102
103static inline void reset_isolation_suitable(pg_data_t *pgdat)
104{
105}
106
107static inline unsigned long compaction_suitable(struct zone *zone, int order)
108{
109 return COMPACT_SKIPPED;
110}
111
112static inline void defer_compaction(struct zone *zone, int order)
113{
114}
115
116static inline bool compaction_deferred(struct zone *zone, int order)
117{
118 return true;
119}
120
121#endif /* CONFIG_COMPACTION */
122
123#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
124extern int compaction_register_node(struct node *node);
125extern void compaction_unregister_node(struct node *node);
126
127#else
128
129static inline int compaction_register_node(struct node *node)
130{
131 return 0;
132}
133
134static inline void compaction_unregister_node(struct node *node)
135{
136}
137#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
138
139#endif /* _LINUX_COMPACTION_H */