1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_COMPACTION_H
3 #define _LINUX_COMPACTION_H
6 * Determines how hard direct compaction should try to succeed.
7 * Lower value means higher priority, analogically to reclaim priority.
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,
16 INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
19 /* Return values for compact_zone() and try_to_compact_pages() */
20 /* When adding new states, please adjust include/trace/events/compaction.h */
22 /* For more detailed tracepoint output - internal to compaction */
23 COMPACT_NOT_SUITABLE_ZONE,
25 * compaction didn't start as it was not possible or direct reclaim
29 /* compaction didn't start as it was deferred due to past failures */
32 /* For more detailed tracepoint output - internal to compaction */
33 COMPACT_NO_SUITABLE_PAGE,
34 /* compaction should continue to another pageblock */
38 * The full zone was compacted scanned but wasn't successful to compact
43 * direct compaction has scanned part of the zone but wasn't successful
44 * to compact suitable pages.
46 COMPACT_PARTIAL_SKIPPED,
48 /* compaction terminated prematurely due to lock contentions */
52 * direct compaction terminated after concluding that the allocation
58 struct alloc_context; /* in mm/internal.h */
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.
65 static inline unsigned long compact_gap(unsigned int order)
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.
83 #ifdef CONFIG_COMPACTION
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,
91 extern void reset_isolation_suitable(pg_data_t *pgdat);
92 extern enum compact_result compaction_suitable(struct zone *zone, int order,
93 unsigned int alloc_flags, int highest_zoneidx);
95 extern void compaction_defer_reset(struct zone *zone, int order,
98 /* Compaction has made some progress and retrying makes sense */
99 static inline bool compaction_made_progress(enum compact_result result)
102 * Even though this might sound confusing this in fact tells us
103 * that the compaction successfully isolated and migrated some
106 if (result == COMPACT_SUCCESS)
112 /* Compaction has failed and it doesn't make much sense to keep retrying. */
113 static inline bool compaction_failed(enum compact_result result)
115 /* All zones were scanned completely and still not result. */
116 if (result == COMPACT_COMPLETE)
122 /* Compaction needs reclaim to be performed first, so it can continue. */
123 static inline bool compaction_needs_reclaim(enum compact_result result)
126 * Compaction backed off due to watermark checks for order-0
127 * so the regular reclaim has to try harder and reclaim something.
129 if (result == COMPACT_SKIPPED)
136 * Compaction has backed off for some reason after doing some work or none
137 * at all. It might be throttling or lock contention. Retrying might be still
138 * worthwhile, but with a higher priority if allowed.
140 static inline bool compaction_withdrawn(enum compact_result result)
143 * If compaction is deferred for high-order allocations, it is
144 * because sync compaction recently failed. If this is the case
145 * and the caller requested a THP allocation, we do not want
146 * to heavily disrupt the system, so we fail the allocation
147 * instead of entering direct reclaim.
149 if (result == COMPACT_DEFERRED)
153 * If compaction in async mode encounters contention or blocks higher
154 * priority task we back off early rather than cause stalls.
156 if (result == COMPACT_CONTENDED)
160 * Page scanners have met but we haven't scanned full zones so this
161 * is a back off in fact.
163 if (result == COMPACT_PARTIAL_SKIPPED)
170 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
173 extern void kcompactd_run(int nid);
174 extern void kcompactd_stop(int nid);
175 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
178 static inline void reset_isolation_suitable(pg_data_t *pgdat)
182 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
183 int alloc_flags, int highest_zoneidx)
185 return COMPACT_SKIPPED;
188 static inline bool compaction_made_progress(enum compact_result result)
193 static inline bool compaction_failed(enum compact_result result)
198 static inline bool compaction_needs_reclaim(enum compact_result result)
203 static inline bool compaction_withdrawn(enum compact_result result)
208 static inline void kcompactd_run(int nid)
211 static inline void kcompactd_stop(int nid)
215 static inline void wakeup_kcompactd(pg_data_t *pgdat,
216 int order, int highest_zoneidx)
220 #endif /* CONFIG_COMPACTION */
223 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
224 extern int compaction_register_node(struct node *node);
225 extern void compaction_unregister_node(struct node *node);
229 static inline int compaction_register_node(struct node *node)
234 static inline void compaction_unregister_node(struct node *node)
237 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
239 #endif /* _LINUX_COMPACTION_H */