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 return 2UL << order; 84 } 85 86 #ifdef CONFIG_COMPACTION 87 extern int sysctl_compact_memory; 88 extern int sysctl_compaction_proactiveness; 89 extern int sysctl_compaction_handler(struct ctl_table *table, int write, 90 void *buffer, size_t *length, loff_t *ppos); 91 extern int sysctl_extfrag_threshold; 92 extern int sysctl_compact_unevictable_allowed; 93 94 extern int extfrag_for_order(struct zone *zone, unsigned int order); 95 extern int fragmentation_index(struct zone *zone, unsigned int order); 96 extern enum compact_result try_to_compact_pages(gfp_t gfp_mask, 97 unsigned int order, unsigned int alloc_flags, 98 const struct alloc_context *ac, enum compact_priority prio, 99 struct page **page); 100 extern void reset_isolation_suitable(pg_data_t *pgdat); 101 extern enum compact_result compaction_suitable(struct zone *zone, int order, 102 unsigned int alloc_flags, int highest_zoneidx); 103 104 extern void defer_compaction(struct zone *zone, int order); 105 extern bool compaction_deferred(struct zone *zone, int order); 106 extern void compaction_defer_reset(struct zone *zone, int order, 107 bool alloc_success); 108 extern bool compaction_restarting(struct zone *zone, int order); 109 110 /* Compaction has made some progress and retrying makes sense */ 111 static inline bool compaction_made_progress(enum compact_result result) 112 { 113 /* 114 * Even though this might sound confusing this in fact tells us 115 * that the compaction successfully isolated and migrated some 116 * pageblocks. 117 */ 118 if (result == COMPACT_SUCCESS) 119 return true; 120 121 return false; 122 } 123 124 /* Compaction has failed and it doesn't make much sense to keep retrying. */ 125 static inline bool compaction_failed(enum compact_result result) 126 { 127 /* All zones were scanned completely and still not result. */ 128 if (result == COMPACT_COMPLETE) 129 return true; 130 131 return false; 132 } 133 134 /* Compaction needs reclaim to be performed first, so it can continue. */ 135 static inline bool compaction_needs_reclaim(enum compact_result result) 136 { 137 /* 138 * Compaction backed off due to watermark checks for order-0 139 * so the regular reclaim has to try harder and reclaim something. 140 */ 141 if (result == COMPACT_SKIPPED) 142 return true; 143 144 return false; 145 } 146 147 /* 148 * Compaction has backed off for some reason after doing some work or none 149 * at all. It might be throttling or lock contention. Retrying might be still 150 * worthwhile, but with a higher priority if allowed. 151 */ 152 static inline bool compaction_withdrawn(enum compact_result result) 153 { 154 /* 155 * If compaction is deferred for high-order allocations, it is 156 * because sync compaction recently failed. If this is the case 157 * and the caller requested a THP allocation, we do not want 158 * to heavily disrupt the system, so we fail the allocation 159 * instead of entering direct reclaim. 160 */ 161 if (result == COMPACT_DEFERRED) 162 return true; 163 164 /* 165 * If compaction in async mode encounters contention or blocks higher 166 * priority task we back off early rather than cause stalls. 167 */ 168 if (result == COMPACT_CONTENDED) 169 return true; 170 171 /* 172 * Page scanners have met but we haven't scanned full zones so this 173 * is a back off in fact. 174 */ 175 if (result == COMPACT_PARTIAL_SKIPPED) 176 return true; 177 178 return false; 179 } 180 181 182 bool compaction_zonelist_suitable(struct alloc_context *ac, int order, 183 int alloc_flags); 184 185 extern int kcompactd_run(int nid); 186 extern void kcompactd_stop(int nid); 187 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx); 188 189 #else 190 static inline void reset_isolation_suitable(pg_data_t *pgdat) 191 { 192 } 193 194 static inline enum compact_result compaction_suitable(struct zone *zone, int order, 195 int alloc_flags, int highest_zoneidx) 196 { 197 return COMPACT_SKIPPED; 198 } 199 200 static inline void defer_compaction(struct zone *zone, int order) 201 { 202 } 203 204 static inline bool compaction_deferred(struct zone *zone, int order) 205 { 206 return true; 207 } 208 209 static inline bool compaction_made_progress(enum compact_result result) 210 { 211 return false; 212 } 213 214 static inline bool compaction_failed(enum compact_result result) 215 { 216 return false; 217 } 218 219 static inline bool compaction_needs_reclaim(enum compact_result result) 220 { 221 return false; 222 } 223 224 static inline bool compaction_withdrawn(enum compact_result result) 225 { 226 return true; 227 } 228 229 static inline int kcompactd_run(int nid) 230 { 231 return 0; 232 } 233 static inline void kcompactd_stop(int nid) 234 { 235 } 236 237 static inline void wakeup_kcompactd(pg_data_t *pgdat, 238 int order, int highest_zoneidx) 239 { 240 } 241 242 #endif /* CONFIG_COMPACTION */ 243 244 struct node; 245 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) 246 extern int compaction_register_node(struct node *node); 247 extern void compaction_unregister_node(struct node *node); 248 249 #else 250 251 static inline int compaction_register_node(struct node *node) 252 { 253 return 0; 254 } 255 256 static inline void compaction_unregister_node(struct node *node) 257 { 258 } 259 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */ 260 261 #endif /* _LINUX_COMPACTION_H */ 262