1 #ifndef _LINUX_COMPACTION_H
2 #define _LINUX_COMPACTION_H
5 * Determines how hard direct compaction should try to succeed.
6 * Lower value means higher priority, analogically to reclaim priority.
8 enum compact_priority {
9 COMPACT_PRIO_SYNC_FULL,
10 MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
11 COMPACT_PRIO_SYNC_LIGHT,
12 DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
14 INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
17 /* Return values for compact_zone() and try_to_compact_pages() */
18 /* When adding new states, please adjust include/trace/events/compaction.h */
20 /* For more detailed tracepoint output - internal to compaction */
21 COMPACT_NOT_SUITABLE_ZONE,
23 * compaction didn't start as it was not possible or direct reclaim
27 /* compaction didn't start as it was deferred due to past failures */
30 /* compaction not active last round */
31 COMPACT_INACTIVE = COMPACT_DEFERRED,
33 /* For more detailed tracepoint output - internal to compaction */
34 COMPACT_NO_SUITABLE_PAGE,
35 /* compaction should continue to another pageblock */
39 * The full zone was compacted scanned but wasn't successfull to compact
44 * direct compaction has scanned part of the zone but wasn't successfull
45 * to compact suitable pages.
47 COMPACT_PARTIAL_SKIPPED,
49 /* compaction terminated prematurely due to lock contentions */
53 * direct compaction terminated after concluding that the allocation
59 struct alloc_context; /* in mm/internal.h */
62 * Number of free order-0 pages that should be available above given watermark
63 * to make sure compaction has reasonable chance of not running out of free
64 * pages that it needs to isolate as migration target during its work.
66 static inline unsigned long compact_gap(unsigned int order)
69 * Although all the isolations for migration are temporary, compaction
70 * free scanner may have up to 1 << order pages on its list and then
71 * try to split an (order - 1) free page. At that point, a gap of
72 * 1 << order might not be enough, so it's safer to require twice that
73 * amount. Note that the number of pages on the list is also
74 * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
75 * that the migrate scanner can have isolated on migrate list, and free
76 * scanner is only invoked when the number of isolated free pages is
77 * lower than that. But it's not worth to complicate the formula here
78 * as a bigger gap for higher orders than strictly necessary can also
79 * improve chances of compaction success.
84 #ifdef CONFIG_COMPACTION
85 extern int sysctl_compact_memory;
86 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
87 void __user *buffer, size_t *length, loff_t *ppos);
88 extern int sysctl_extfrag_threshold;
89 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
90 void __user *buffer, size_t *length, loff_t *ppos);
91 extern int sysctl_compact_unevictable_allowed;
93 extern int fragmentation_index(struct zone *zone, unsigned int order);
94 extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
95 unsigned int order, unsigned int alloc_flags,
96 const struct alloc_context *ac, enum compact_priority prio);
97 extern void reset_isolation_suitable(pg_data_t *pgdat);
98 extern enum compact_result compaction_suitable(struct zone *zone, int order,
99 unsigned int alloc_flags, int classzone_idx);
101 extern void defer_compaction(struct zone *zone, int order);
102 extern bool compaction_deferred(struct zone *zone, int order);
103 extern void compaction_defer_reset(struct zone *zone, int order,
105 extern bool compaction_restarting(struct zone *zone, int order);
107 /* Compaction has made some progress and retrying makes sense */
108 static inline bool compaction_made_progress(enum compact_result result)
111 * Even though this might sound confusing this in fact tells us
112 * that the compaction successfully isolated and migrated some
115 if (result == COMPACT_SUCCESS)
121 /* Compaction has failed and it doesn't make much sense to keep retrying. */
122 static inline bool compaction_failed(enum compact_result result)
124 /* All zones were scanned completely and still not result. */
125 if (result == COMPACT_COMPLETE)
132 * Compaction has backed off for some reason. It might be throttling or
133 * lock contention. Retrying is still worthwhile.
135 static inline bool compaction_withdrawn(enum compact_result result)
138 * Compaction backed off due to watermark checks for order-0
139 * so the regular reclaim has to try harder and reclaim something.
141 if (result == COMPACT_SKIPPED)
145 * If compaction is deferred for high-order allocations, it is
146 * because sync compaction recently failed. If this is the case
147 * and the caller requested a THP allocation, we do not want
148 * to heavily disrupt the system, so we fail the allocation
149 * instead of entering direct reclaim.
151 if (result == COMPACT_DEFERRED)
155 * If compaction in async mode encounters contention or blocks higher
156 * priority task we back off early rather than cause stalls.
158 if (result == COMPACT_CONTENDED)
162 * Page scanners have met but we haven't scanned full zones so this
163 * is a back off in fact.
165 if (result == COMPACT_PARTIAL_SKIPPED)
172 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
175 extern int kcompactd_run(int nid);
176 extern void kcompactd_stop(int nid);
177 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
180 static inline void reset_isolation_suitable(pg_data_t *pgdat)
184 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
185 int alloc_flags, int classzone_idx)
187 return COMPACT_SKIPPED;
190 static inline void defer_compaction(struct zone *zone, int order)
194 static inline bool compaction_deferred(struct zone *zone, int order)
199 static inline bool compaction_made_progress(enum compact_result result)
204 static inline bool compaction_failed(enum compact_result result)
209 static inline bool compaction_withdrawn(enum compact_result result)
214 static inline int kcompactd_run(int nid)
218 static inline void kcompactd_stop(int nid)
222 static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
226 #endif /* CONFIG_COMPACTION */
228 #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 */