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 compaction_proactiveness_sysctl_handler(struct ctl_table
*table
,
88 int write
, void *buffer
, size_t *length
, loff_t
*ppos
);
89 extern int sysctl_extfrag_threshold
;
90 extern int sysctl_compact_unevictable_allowed
;
92 extern unsigned int extfrag_for_order(struct zone
*zone
, unsigned int order
);
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
,
98 extern void reset_isolation_suitable(pg_data_t
*pgdat
);
99 extern enum compact_result
compaction_suitable(struct zone
*zone
, int order
,
100 unsigned int alloc_flags
, int highest_zoneidx
);
102 extern void compaction_defer_reset(struct zone
*zone
, int order
,
105 /* Compaction has made some progress and retrying makes sense */
106 static inline bool compaction_made_progress(enum compact_result result
)
109 * Even though this might sound confusing this in fact tells us
110 * that the compaction successfully isolated and migrated some
113 if (result
== COMPACT_SUCCESS
)
119 /* Compaction has failed and it doesn't make much sense to keep retrying. */
120 static inline bool compaction_failed(enum compact_result result
)
122 /* All zones were scanned completely and still not result. */
123 if (result
== COMPACT_COMPLETE
)
129 /* Compaction needs reclaim to be performed first, so it can continue. */
130 static inline bool compaction_needs_reclaim(enum compact_result result
)
133 * Compaction backed off due to watermark checks for order-0
134 * so the regular reclaim has to try harder and reclaim something.
136 if (result
== COMPACT_SKIPPED
)
143 * Compaction has backed off for some reason after doing some work or none
144 * at all. It might be throttling or lock contention. Retrying might be still
145 * worthwhile, but with a higher priority if allowed.
147 static inline bool compaction_withdrawn(enum compact_result result
)
150 * If compaction is deferred for high-order allocations, it is
151 * because sync compaction recently failed. If this is the case
152 * and the caller requested a THP allocation, we do not want
153 * to heavily disrupt the system, so we fail the allocation
154 * instead of entering direct reclaim.
156 if (result
== COMPACT_DEFERRED
)
160 * If compaction in async mode encounters contention or blocks higher
161 * priority task we back off early rather than cause stalls.
163 if (result
== COMPACT_CONTENDED
)
167 * Page scanners have met but we haven't scanned full zones so this
168 * is a back off in fact.
170 if (result
== COMPACT_PARTIAL_SKIPPED
)
177 bool compaction_zonelist_suitable(struct alloc_context
*ac
, int order
,
180 extern int kcompactd_run(int nid
);
181 extern void kcompactd_stop(int nid
);
182 extern void wakeup_kcompactd(pg_data_t
*pgdat
, int order
, int highest_zoneidx
);
185 static inline void reset_isolation_suitable(pg_data_t
*pgdat
)
189 static inline enum compact_result
compaction_suitable(struct zone
*zone
, int order
,
190 int alloc_flags
, int highest_zoneidx
)
192 return COMPACT_SKIPPED
;
195 static inline bool compaction_made_progress(enum compact_result result
)
200 static inline bool compaction_failed(enum compact_result result
)
205 static inline bool compaction_needs_reclaim(enum compact_result result
)
210 static inline bool compaction_withdrawn(enum compact_result result
)
215 static inline int kcompactd_run(int nid
)
219 static inline void kcompactd_stop(int nid
)
223 static inline void wakeup_kcompactd(pg_data_t
*pgdat
,
224 int order
, int highest_zoneidx
)
228 #endif /* CONFIG_COMPACTION */
231 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
232 extern int compaction_register_node(struct node
*node
);
233 extern void compaction_unregister_node(struct node
*node
);
237 static inline int compaction_register_node(struct node
*node
)
242 static inline void compaction_unregister_node(struct node
*node
)
245 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
247 #endif /* _LINUX_COMPACTION_H */