xref: /linux/include/linux/compaction.h (revision 833dfc00)
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  */
compact_gap(unsigned int order)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
reset_isolation_suitable(pg_data_t * pgdat)106 static inline void reset_isolation_suitable(pg_data_t *pgdat)
107 {
108 }
109 
compaction_suitable(struct zone * zone,int order,int highest_zoneidx)110 static inline bool compaction_suitable(struct zone *zone, int order,
111 						      int highest_zoneidx)
112 {
113 	return false;
114 }
115 
kcompactd_run(int nid)116 static inline void kcompactd_run(int nid)
117 {
118 }
kcompactd_stop(int nid)119 static inline void kcompactd_stop(int nid)
120 {
121 }
122 
wakeup_kcompactd(pg_data_t * pgdat,int order,int highest_zoneidx)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 
compaction_register_node(struct node * node)137 static inline int compaction_register_node(struct node *node)
138 {
139 	return 0;
140 }
141 
compaction_unregister_node(struct node * node)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