Linux kernel mirror (for testing)
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1#ifndef _LINUX_COMPACTION_H
2#define _LINUX_COMPACTION_H
3
4/*
5 * Determines how hard direct compaction should try to succeed.
6 * Lower value means higher priority, analogically to reclaim priority.
7 */
8enum compact_priority {
9 COMPACT_PRIO_SYNC_LIGHT,
10 MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
11 DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
12 COMPACT_PRIO_ASYNC,
13 INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
14};
15
16/* Return values for compact_zone() and try_to_compact_pages() */
17/* When adding new states, please adjust include/trace/events/compaction.h */
18enum compact_result {
19 /* For more detailed tracepoint output - internal to compaction */
20 COMPACT_NOT_SUITABLE_ZONE,
21 /*
22 * compaction didn't start as it was not possible or direct reclaim
23 * was more suitable
24 */
25 COMPACT_SKIPPED,
26 /* compaction didn't start as it was deferred due to past failures */
27 COMPACT_DEFERRED,
28
29 /* compaction not active last round */
30 COMPACT_INACTIVE = 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 successfull to compact
39 * suitable pages.
40 */
41 COMPACT_COMPLETE,
42 /*
43 * direct compaction has scanned part of the zone but wasn't successfull
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 partially compacted a zone and there might be
53 * suitable pages
54 */
55 COMPACT_PARTIAL,
56};
57
58struct alloc_context; /* in mm/internal.h */
59
60#ifdef CONFIG_COMPACTION
61extern int sysctl_compact_memory;
62extern int sysctl_compaction_handler(struct ctl_table *table, int write,
63 void __user *buffer, size_t *length, loff_t *ppos);
64extern int sysctl_extfrag_threshold;
65extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
66 void __user *buffer, size_t *length, loff_t *ppos);
67extern int sysctl_compact_unevictable_allowed;
68
69extern int fragmentation_index(struct zone *zone, unsigned int order);
70extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
71 unsigned int order, unsigned int alloc_flags,
72 const struct alloc_context *ac, enum compact_priority prio);
73extern void compact_pgdat(pg_data_t *pgdat, int order);
74extern void reset_isolation_suitable(pg_data_t *pgdat);
75extern enum compact_result compaction_suitable(struct zone *zone, int order,
76 unsigned int alloc_flags, int classzone_idx);
77
78extern void defer_compaction(struct zone *zone, int order);
79extern bool compaction_deferred(struct zone *zone, int order);
80extern void compaction_defer_reset(struct zone *zone, int order,
81 bool alloc_success);
82extern bool compaction_restarting(struct zone *zone, int order);
83
84/* Compaction has made some progress and retrying makes sense */
85static inline bool compaction_made_progress(enum compact_result result)
86{
87 /*
88 * Even though this might sound confusing this in fact tells us
89 * that the compaction successfully isolated and migrated some
90 * pageblocks.
91 */
92 if (result == COMPACT_PARTIAL)
93 return true;
94
95 return false;
96}
97
98/* Compaction has failed and it doesn't make much sense to keep retrying. */
99static inline bool compaction_failed(enum compact_result result)
100{
101 /* All zones were scanned completely and still not result. */
102 if (result == COMPACT_COMPLETE)
103 return true;
104
105 return false;
106}
107
108/*
109 * Compaction has backed off for some reason. It might be throttling or
110 * lock contention. Retrying is still worthwhile.
111 */
112static inline bool compaction_withdrawn(enum compact_result result)
113{
114 /*
115 * Compaction backed off due to watermark checks for order-0
116 * so the regular reclaim has to try harder and reclaim something.
117 */
118 if (result == COMPACT_SKIPPED)
119 return true;
120
121 /*
122 * If compaction is deferred for high-order allocations, it is
123 * because sync compaction recently failed. If this is the case
124 * and the caller requested a THP allocation, we do not want
125 * to heavily disrupt the system, so we fail the allocation
126 * instead of entering direct reclaim.
127 */
128 if (result == COMPACT_DEFERRED)
129 return true;
130
131 /*
132 * If compaction in async mode encounters contention or blocks higher
133 * priority task we back off early rather than cause stalls.
134 */
135 if (result == COMPACT_CONTENDED)
136 return true;
137
138 /*
139 * Page scanners have met but we haven't scanned full zones so this
140 * is a back off in fact.
141 */
142 if (result == COMPACT_PARTIAL_SKIPPED)
143 return true;
144
145 return false;
146}
147
148
149bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
150 int alloc_flags);
151
152extern int kcompactd_run(int nid);
153extern void kcompactd_stop(int nid);
154extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
155
156#else
157static inline void compact_pgdat(pg_data_t *pgdat, int order)
158{
159}
160
161static inline void reset_isolation_suitable(pg_data_t *pgdat)
162{
163}
164
165static inline enum compact_result compaction_suitable(struct zone *zone, int order,
166 int alloc_flags, int classzone_idx)
167{
168 return COMPACT_SKIPPED;
169}
170
171static inline void defer_compaction(struct zone *zone, int order)
172{
173}
174
175static inline bool compaction_deferred(struct zone *zone, int order)
176{
177 return true;
178}
179
180static inline bool compaction_made_progress(enum compact_result result)
181{
182 return false;
183}
184
185static inline bool compaction_failed(enum compact_result result)
186{
187 return false;
188}
189
190static inline bool compaction_withdrawn(enum compact_result result)
191{
192 return true;
193}
194
195static inline int kcompactd_run(int nid)
196{
197 return 0;
198}
199static inline void kcompactd_stop(int nid)
200{
201}
202
203static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
204{
205}
206
207#endif /* CONFIG_COMPACTION */
208
209#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
210struct node;
211extern int compaction_register_node(struct node *node);
212extern void compaction_unregister_node(struct node *node);
213
214#else
215
216static inline int compaction_register_node(struct node *node)
217{
218 return 0;
219}
220
221static inline void compaction_unregister_node(struct node *node)
222{
223}
224#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
225
226#endif /* _LINUX_COMPACTION_H */