1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_COMPACTION_H
3#define _LINUX_COMPACTION_H
4
5/*
6 * Determines how hard direct compaction should try to succeed.
7 * Lower value means higher priority, analogically to reclaim priority.
8 */
9enum compact_priority {
10	COMPACT_PRIO_SYNC_FULL,
11	MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
12	COMPACT_PRIO_SYNC_LIGHT,
13	MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
14	DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
15	COMPACT_PRIO_ASYNC,
16	INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
17};
18
19/* Return values for compact_zone() and try_to_compact_pages() */
20/* When adding new states, please adjust include/trace/events/compaction.h */
21enum compact_result {
22	/* For more detailed tracepoint output - internal to compaction */
23	COMPACT_NOT_SUITABLE_ZONE,
24	/*
25	 * compaction didn't start as it was not possible or direct reclaim
26	 * was more suitable
27	 */
28	COMPACT_SKIPPED,
29	/* compaction didn't start as it was deferred due to past failures */
30	COMPACT_DEFERRED,
31
32	/* For more detailed tracepoint output - internal to compaction */
33	COMPACT_NO_SUITABLE_PAGE,
34	/* compaction should continue to another pageblock */
35	COMPACT_CONTINUE,
36
37	/*
38	 * The full zone was compacted scanned but wasn't successful to compact
39	 * suitable pages.
40	 */
41	COMPACT_COMPLETE,
42	/*
43	 * direct compaction has scanned part of the zone but wasn't successful
44	 * to compact suitable pages.
45	 */
46	COMPACT_PARTIAL_SKIPPED,
47
48	/* compaction terminated prematurely due to lock contentions */
49	COMPACT_CONTENDED,
50
51	/*
52	 * direct compaction terminated after concluding that the allocation
53	 * should now succeed
54	 */
55	COMPACT_SUCCESS,
56};
57
58struct alloc_context; /* in mm/internal.h */
59
60/*
61 * Number of free order-0 pages that should be available above given watermark
62 * to make sure compaction has reasonable chance of not running out of free
63 * pages that it needs to isolate as migration target during its work.
64 */
65static inline unsigned long compact_gap(unsigned int order)
66{
67	/*
68	 * Although all the isolations for migration are temporary, compaction
69	 * free scanner may have up to 1 << order pages on its list and then
70	 * try to split an (order - 1) free page. At that point, a gap of
71	 * 1 << order might not be enough, so it's safer to require twice that
72	 * amount. Note that the number of pages on the list is also
73	 * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
74	 * that the migrate scanner can have isolated on migrate list, and free
75	 * scanner is only invoked when the number of isolated free pages is
76	 * lower than that. But it's not worth to complicate the formula here
77	 * as a bigger gap for higher orders than strictly necessary can also
78	 * improve chances of compaction success.
79	 */
80	return 2UL << order;
81}
82
83#ifdef CONFIG_COMPACTION
84
85extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
86extern int fragmentation_index(struct zone *zone, unsigned int order);
87extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
88		unsigned int order, unsigned int alloc_flags,
89		const struct alloc_context *ac, enum compact_priority prio,
90		struct page **page);
91extern void reset_isolation_suitable(pg_data_t *pgdat);
92extern bool compaction_suitable(struct zone *zone, int order,
93					       int highest_zoneidx);
94
95extern void compaction_defer_reset(struct zone *zone, int order,
96				bool alloc_success);
97
98bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
99					int alloc_flags);
100
101extern void __meminit kcompactd_run(int nid);
102extern void __meminit kcompactd_stop(int nid);
103extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
104
105#else
106static inline void reset_isolation_suitable(pg_data_t *pgdat)
107{
108}
109
110static inline bool compaction_suitable(struct zone *zone, int order,
111						      int highest_zoneidx)
112{
113	return false;
114}
115
116static inline void kcompactd_run(int nid)
117{
118}
119static inline void kcompactd_stop(int nid)
120{
121}
122
123static inline void wakeup_kcompactd(pg_data_t *pgdat,
124				int order, int highest_zoneidx)
125{
126}
127
128#endif /* CONFIG_COMPACTION */
129
130struct node;
131#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
132extern int compaction_register_node(struct node *node);
133extern void compaction_unregister_node(struct node *node);
134
135#else
136
137static inline int compaction_register_node(struct node *node)
138{
139	return 0;
140}
141
142static inline void compaction_unregister_node(struct node *node)
143{
144}
145#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
146
147#endif /* _LINUX_COMPACTION_H */
148