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
84 extern unsigned int sysctl_compaction_proactiveness;
85 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
86 void *buffer, size_t *length, loff_t *ppos);
87 extern int sysctl_extfrag_threshold;
88 extern int sysctl_compact_unevictable_allowed;
90 extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
91 extern int fragmentation_index(struct zone *zone, unsigned int order);
92 extern 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,
96 extern void reset_isolation_suitable(pg_data_t *pgdat);
97 extern enum compact_result compaction_suitable(struct zone *zone, int order,
98 unsigned int alloc_flags, int highest_zoneidx);
100 extern void compaction_defer_reset(struct zone *zone, int order,
103 /* Compaction has made some progress and retrying makes sense */
104 static inline bool compaction_made_progress(enum compact_result result)
107 * Even though this might sound confusing this in fact tells us
108 * that the compaction successfully isolated and migrated some
111 if (result == COMPACT_SUCCESS)
117 /* Compaction has failed and it doesn't make much sense to keep retrying. */
118 static inline bool compaction_failed(enum compact_result result)
120 /* All zones were scanned completely and still not result. */
121 if (result == COMPACT_COMPLETE)
127 /* Compaction needs reclaim to be performed first, so it can continue. */
128 static inline bool compaction_needs_reclaim(enum compact_result result)
131 * Compaction backed off due to watermark checks for order-0
132 * so the regular reclaim has to try harder and reclaim something.
134 if (result == COMPACT_SKIPPED)
141 * Compaction has backed off for some reason after doing some work or none
142 * at all. It might be throttling or lock contention. Retrying might be still
143 * worthwhile, but with a higher priority if allowed.
145 static inline bool compaction_withdrawn(enum compact_result result)
148 * If compaction is deferred for high-order allocations, it is
149 * because sync compaction recently failed. If this is the case
150 * and the caller requested a THP allocation, we do not want
151 * to heavily disrupt the system, so we fail the allocation
152 * instead of entering direct reclaim.
154 if (result == COMPACT_DEFERRED)
158 * If compaction in async mode encounters contention or blocks higher
159 * priority task we back off early rather than cause stalls.
161 if (result == COMPACT_CONTENDED)
165 * Page scanners have met but we haven't scanned full zones so this
166 * is a back off in fact.
168 if (result == COMPACT_PARTIAL_SKIPPED)
175 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
178 extern int kcompactd_run(int nid);
179 extern void kcompactd_stop(int nid);
180 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
183 static inline void reset_isolation_suitable(pg_data_t *pgdat)
187 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
188 int alloc_flags, int highest_zoneidx)
190 return COMPACT_SKIPPED;
193 static inline bool compaction_made_progress(enum compact_result result)
198 static inline bool compaction_failed(enum compact_result result)
203 static inline bool compaction_needs_reclaim(enum compact_result result)
208 static inline bool compaction_withdrawn(enum compact_result result)
213 static inline int kcompactd_run(int nid)
217 static inline void kcompactd_stop(int nid)
221 static inline void wakeup_kcompactd(pg_data_t *pgdat,
222 int order, int highest_zoneidx)
226 #endif /* CONFIG_COMPACTION */
229 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
230 extern int compaction_register_node(struct node *node);
231 extern void compaction_unregister_node(struct node *node);
235 static inline int compaction_register_node(struct node *node)
240 static inline void compaction_unregister_node(struct node *node)
243 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
245 #endif /* _LINUX_COMPACTION_H */