compaction.h

  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
 83static inline int current_is_kcompactd(void)
 84{
 85	return current->flags & PF_KCOMPACTD;
 86}
 87
 88#ifdef CONFIG_COMPACTION
 89
 90extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
 91extern int fragmentation_index(struct zone *zone, unsigned int order);
 92extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
 93		unsigned int order, unsigned int alloc_flags,
 94		const struct alloc_context *ac, enum compact_priority prio,
 95		struct page **page);
 96extern void reset_isolation_suitable(pg_data_t *pgdat);
 97extern bool compaction_suitable(struct zone *zone, int order,
 98				unsigned long watermark, int highest_zoneidx);
 99
100extern void compaction_defer_reset(struct zone *zone, int order,
101				bool alloc_success);
102
103bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
104					int alloc_flags);
105
106extern void __meminit kcompactd_run(int nid);
107extern void __meminit kcompactd_stop(int nid);
108extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
109
110#else
111static inline void reset_isolation_suitable(pg_data_t *pgdat)
112{
113}
114
115static inline bool compaction_suitable(struct zone *zone, int order,
116				       unsigned long watermark,
117				       int highest_zoneidx)
118{
119	return false;
120}
121
122static inline void kcompactd_run(int nid)
123{
124}
125static inline void kcompactd_stop(int nid)
126{
127}
128
129static inline void wakeup_kcompactd(pg_data_t *pgdat,
130				int order, int highest_zoneidx)
131{
132}
133
134#endif /* CONFIG_COMPACTION */
135
136struct node;
137#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
138extern int compaction_register_node(struct node *node);
139extern void compaction_unregister_node(struct node *node);
140
141#else
142
143static inline int compaction_register_node(struct node *node)
144{
145	return 0;
146}
147
148static inline void compaction_unregister_node(struct node *node)
149{
150}
151#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
152
153#endif /* _LINUX_COMPACTION_H */