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1 : : /* SPDX-License-Identifier: GPL-2.0 */
2 : : #ifndef _LINUX_COMPACTION_H
3 : : #define _LINUX_COMPACTION_H
4 : :
5 : : /*
6 : : * Determines how hard direct compaction should try to succeed.
7 : : * Lower value means higher priority, analogically to reclaim priority.
8 : : */
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,
15 : : COMPACT_PRIO_ASYNC,
16 : : INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
17 : : };
18 : :
19 : : /* Return values for compact_zone() and try_to_compact_pages() */
20 : : /* When adding new states, please adjust include/trace/events/compaction.h */
21 : : enum compact_result {
22 : : /* For more detailed tracepoint output - internal to compaction */
23 : : COMPACT_NOT_SUITABLE_ZONE,
24 : : /*
25 : : * compaction didn't start as it was not possible or direct reclaim
26 : : * was more suitable
27 : : */
28 : : COMPACT_SKIPPED,
29 : : /* compaction didn't start as it was deferred due to past failures */
30 : : COMPACT_DEFERRED,
31 : :
32 : : /* compaction not active last round */
33 : : COMPACT_INACTIVE = COMPACT_DEFERRED,
34 : :
35 : : /* For more detailed tracepoint output - internal to compaction */
36 : : COMPACT_NO_SUITABLE_PAGE,
37 : : /* compaction should continue to another pageblock */
38 : : COMPACT_CONTINUE,
39 : :
40 : : /*
41 : : * The full zone was compacted scanned but wasn't successfull to compact
42 : : * suitable pages.
43 : : */
44 : : COMPACT_COMPLETE,
45 : : /*
46 : : * direct compaction has scanned part of the zone but wasn't successfull
47 : : * to compact suitable pages.
48 : : */
49 : : COMPACT_PARTIAL_SKIPPED,
50 : :
51 : : /* compaction terminated prematurely due to lock contentions */
52 : : COMPACT_CONTENDED,
53 : :
54 : : /*
55 : : * direct compaction terminated after concluding that the allocation
56 : : * should now succeed
57 : : */
58 : : COMPACT_SUCCESS,
59 : : };
60 : :
61 : : struct alloc_context; /* in mm/internal.h */
62 : :
63 : : /*
64 : : * Number of free order-0 pages that should be available above given watermark
65 : : * to make sure compaction has reasonable chance of not running out of free
66 : : * pages that it needs to isolate as migration target during its work.
67 : : */
68 : : static inline unsigned long compact_gap(unsigned int order)
69 : : {
70 : : /*
71 : : * Although all the isolations for migration are temporary, compaction
72 : : * free scanner may have up to 1 << order pages on its list and then
73 : : * try to split an (order - 1) free page. At that point, a gap of
74 : : * 1 << order might not be enough, so it's safer to require twice that
75 : : * amount. Note that the number of pages on the list is also
76 : : * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
77 : : * that the migrate scanner can have isolated on migrate list, and free
78 : : * scanner is only invoked when the number of isolated free pages is
79 : : * lower than that. But it's not worth to complicate the formula here
80 : : * as a bigger gap for higher orders than strictly necessary can also
81 : : * improve chances of compaction success.
82 : : */
83 : 0 : return 2UL << order;
84 : : }
85 : :
86 : : #ifdef CONFIG_COMPACTION
87 : : extern int sysctl_compact_memory;
88 : : extern int sysctl_compaction_handler(struct ctl_table *table, int write,
89 : : void __user *buffer, size_t *length, loff_t *ppos);
90 : : extern int sysctl_extfrag_threshold;
91 : : extern int sysctl_compact_unevictable_allowed;
92 : :
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 : : struct page **page);
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 classzone_idx);
101 : :
102 : : extern void defer_compaction(struct zone *zone, int order);
103 : : extern bool compaction_deferred(struct zone *zone, int order);
104 : : extern void compaction_defer_reset(struct zone *zone, int order,
105 : : bool alloc_success);
106 : : extern bool compaction_restarting(struct zone *zone, int order);
107 : :
108 : : /* Compaction has made some progress and retrying makes sense */
109 : : static inline bool compaction_made_progress(enum compact_result result)
110 : : {
111 : : /*
112 : : * Even though this might sound confusing this in fact tells us
113 : : * that the compaction successfully isolated and migrated some
114 : : * pageblocks.
115 : : */
116 [ # # ]: 0 : if (result == COMPACT_SUCCESS)
117 : : return true;
118 : :
119 : : return false;
120 : : }
121 : :
122 : : /* Compaction has failed and it doesn't make much sense to keep retrying. */
123 : : static inline bool compaction_failed(enum compact_result result)
124 : : {
125 : : /* All zones were scanned completely and still not result. */
126 [ # # # # ]: 0 : if (result == COMPACT_COMPLETE)
127 : : return true;
128 : :
129 : : return false;
130 : : }
131 : :
132 : : /* Compaction needs reclaim to be performed first, so it can continue. */
133 : : static inline bool compaction_needs_reclaim(enum compact_result result)
134 : : {
135 : : /*
136 : : * Compaction backed off due to watermark checks for order-0
137 : : * so the regular reclaim has to try harder and reclaim something.
138 : : */
139 [ # # ]: 0 : if (result == COMPACT_SKIPPED)
140 : : return true;
141 : :
142 : : return false;
143 : : }
144 : :
145 : : /*
146 : : * Compaction has backed off for some reason after doing some work or none
147 : : * at all. It might be throttling or lock contention. Retrying might be still
148 : : * worthwhile, but with a higher priority if allowed.
149 : : */
150 : : static inline bool compaction_withdrawn(enum compact_result result)
151 : : {
152 : : /*
153 : : * If compaction is deferred for high-order allocations, it is
154 : : * because sync compaction recently failed. If this is the case
155 : : * and the caller requested a THP allocation, we do not want
156 : : * to heavily disrupt the system, so we fail the allocation
157 : : * instead of entering direct reclaim.
158 : : */
159 [ # # # # ]: 0 : if (result == COMPACT_DEFERRED)
160 : : return true;
161 : :
162 : : /*
163 : : * If compaction in async mode encounters contention or blocks higher
164 : : * priority task we back off early rather than cause stalls.
165 : : */
166 [ # # # # ]: 0 : if (result == COMPACT_CONTENDED)
167 : : return true;
168 : :
169 : : /*
170 : : * Page scanners have met but we haven't scanned full zones so this
171 : : * is a back off in fact.
172 : : */
173 [ # # # # ]: 0 : if (result == COMPACT_PARTIAL_SKIPPED)
174 : : return true;
175 : :
176 : : return false;
177 : : }
178 : :
179 : :
180 : : bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
181 : : int alloc_flags);
182 : :
183 : : extern int kcompactd_run(int nid);
184 : : extern void kcompactd_stop(int nid);
185 : : extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
186 : :
187 : : #else
188 : : static inline void reset_isolation_suitable(pg_data_t *pgdat)
189 : : {
190 : : }
191 : :
192 : : static inline enum compact_result compaction_suitable(struct zone *zone, int order,
193 : : int alloc_flags, int classzone_idx)
194 : : {
195 : : return COMPACT_SKIPPED;
196 : : }
197 : :
198 : : static inline void defer_compaction(struct zone *zone, int order)
199 : : {
200 : : }
201 : :
202 : : static inline bool compaction_deferred(struct zone *zone, int order)
203 : : {
204 : : return true;
205 : : }
206 : :
207 : : static inline bool compaction_made_progress(enum compact_result result)
208 : : {
209 : : return false;
210 : : }
211 : :
212 : : static inline bool compaction_failed(enum compact_result result)
213 : : {
214 : : return false;
215 : : }
216 : :
217 : : static inline bool compaction_needs_reclaim(enum compact_result result)
218 : : {
219 : : return false;
220 : : }
221 : :
222 : : static inline bool compaction_withdrawn(enum compact_result result)
223 : : {
224 : : return true;
225 : : }
226 : :
227 : : static inline int kcompactd_run(int nid)
228 : : {
229 : : return 0;
230 : : }
231 : : static inline void kcompactd_stop(int nid)
232 : : {
233 : : }
234 : :
235 : : static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
236 : : {
237 : : }
238 : :
239 : : #endif /* CONFIG_COMPACTION */
240 : :
241 : : struct node;
242 : : #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
243 : : extern int compaction_register_node(struct node *node);
244 : : extern void compaction_unregister_node(struct node *node);
245 : :
246 : : #else
247 : :
248 : : static inline int compaction_register_node(struct node *node)
249 : : {
250 : : return 0;
251 : : }
252 : :
253 : : static inline void compaction_unregister_node(struct node *node)
254 : : {
255 : : }
256 : : #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
257 : :
258 : : #endif /* _LINUX_COMPACTION_H */
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