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 */
9 enum 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 */
21 enum 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
58 struct 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 */
65 static 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
85 extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
86 extern int fragmentation_index(struct zone *zone, unsigned int order);
87 extern 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);
91 extern void reset_isolation_suitable(pg_data_t *pgdat);
92 extern bool compaction_suitable(struct zone *zone, int order,
93 int highest_zoneidx);
94
95 extern void compaction_defer_reset(struct zone *zone, int order,
96 bool alloc_success);
97
98 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
99 int alloc_flags);
100
101 extern void __meminit kcompactd_run(int nid);
102 extern void __meminit kcompactd_stop(int nid);
103 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
104
105 #else
106 static inline void reset_isolation_suitable(pg_data_t *pgdat)
107 {
108 }
109
110 static inline bool compaction_suitable(struct zone *zone, int order,
111 int highest_zoneidx)
112 {
113 return false;
114 }
115
116 static inline void kcompactd_run(int nid)
117 {
118 }
119 static inline void kcompactd_stop(int nid)
120 {
121 }
122
123 static inline void wakeup_kcompactd(pg_data_t *pgdat,
124 int order, int highest_zoneidx)
125 {
126 }
127
128 #endif /* CONFIG_COMPACTION */
129
130 struct node;
131 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
132 extern int compaction_register_node(struct node *node);
133 extern void compaction_unregister_node(struct node *node);
134
135 #else
136
137 static inline int compaction_register_node(struct node *node)
138 {
139 return 0;
140 }
141
142 static 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
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