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 */ 8 enum compact_priority { 9 COMPACT_PRIO_SYNC_FULL, 10 MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL, 11 COMPACT_PRIO_SYNC_LIGHT, 12 MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, 13 DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, 14 COMPACT_PRIO_ASYNC, 15 INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC 16 }; 17 18 /* Return values for compact_zone() and try_to_compact_pages() */ 19 /* When adding new states, please adjust include/trace/events/compaction.h */ 20 enum compact_result { 21 /* For more detailed tracepoint output - internal to compaction */ 22 COMPACT_NOT_SUITABLE_ZONE, 23 /* 24 * compaction didn't start as it was not possible or direct reclaim 25 * was more suitable 26 */ 27 COMPACT_SKIPPED, 28 /* compaction didn't start as it was deferred due to past failures */ 29 COMPACT_DEFERRED, 30 31 /* compaction not active last round */ 32 COMPACT_INACTIVE = COMPACT_DEFERRED, 33 34 /* For more detailed tracepoint output - internal to compaction */ 35 COMPACT_NO_SUITABLE_PAGE, 36 /* compaction should continue to another pageblock */ 37 COMPACT_CONTINUE, 38 39 /* 40 * The full zone was compacted scanned but wasn't successfull to compact 41 * suitable pages. 42 */ 43 COMPACT_COMPLETE, 44 /* 45 * direct compaction has scanned part of the zone but wasn't successfull 46 * to compact suitable pages. 47 */ 48 COMPACT_PARTIAL_SKIPPED, 49 50 /* compaction terminated prematurely due to lock contentions */ 51 COMPACT_CONTENDED, 52 53 /* 54 * direct compaction terminated after concluding that the allocation 55 * should now succeed 56 */ 57 COMPACT_SUCCESS, 58 }; 59 60 struct alloc_context; /* in mm/internal.h */ 61 62 /* 63 * Number of free order-0 pages that should be available above given watermark 64 * to make sure compaction has reasonable chance of not running out of free 65 * pages that it needs to isolate as migration target during its work. 66 */ 67 static inline unsigned long compact_gap(unsigned int order) 68 { 69 /* 70 * Although all the isolations for migration are temporary, compaction 71 * free scanner may have up to 1 << order pages on its list and then 72 * try to split an (order - 1) free page. At that point, a gap of 73 * 1 << order might not be enough, so it's safer to require twice that 74 * amount. Note that the number of pages on the list is also 75 * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum 76 * that the migrate scanner can have isolated on migrate list, and free 77 * scanner is only invoked when the number of isolated free pages is 78 * lower than that. But it's not worth to complicate the formula here 79 * as a bigger gap for higher orders than strictly necessary can also 80 * improve chances of compaction success. 81 */ 82 return 2UL << order; 83 } 84 85 #ifdef CONFIG_COMPACTION 86 extern int sysctl_compact_memory; 87 extern int sysctl_compaction_handler(struct ctl_table *table, int write, 88 void __user *buffer, size_t *length, loff_t *ppos); 89 extern int sysctl_extfrag_threshold; 90 extern int sysctl_extfrag_handler(struct ctl_table *table, int write, 91 void __user *buffer, size_t *length, loff_t *ppos); 92 extern int sysctl_compact_unevictable_allowed; 93 94 extern int fragmentation_index(struct zone *zone, unsigned int order); 95 extern enum compact_result try_to_compact_pages(gfp_t gfp_mask, 96 unsigned int order, unsigned int alloc_flags, 97 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 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 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 if (result == COMPACT_COMPLETE) 127 return true; 128 129 return false; 130 } 131 132 /* 133 * Compaction has backed off for some reason. It might be throttling or 134 * lock contention. Retrying is still worthwhile. 135 */ 136 static inline bool compaction_withdrawn(enum compact_result result) 137 { 138 /* 139 * Compaction backed off due to watermark checks for order-0 140 * so the regular reclaim has to try harder and reclaim something. 141 */ 142 if (result == COMPACT_SKIPPED) 143 return true; 144 145 /* 146 * If compaction is deferred for high-order allocations, it is 147 * because sync compaction recently failed. If this is the case 148 * and the caller requested a THP allocation, we do not want 149 * to heavily disrupt the system, so we fail the allocation 150 * instead of entering direct reclaim. 151 */ 152 if (result == COMPACT_DEFERRED) 153 return true; 154 155 /* 156 * If compaction in async mode encounters contention or blocks higher 157 * priority task we back off early rather than cause stalls. 158 */ 159 if (result == COMPACT_CONTENDED) 160 return true; 161 162 /* 163 * Page scanners have met but we haven't scanned full zones so this 164 * is a back off in fact. 165 */ 166 if (result == COMPACT_PARTIAL_SKIPPED) 167 return true; 168 169 return false; 170 } 171 172 173 bool compaction_zonelist_suitable(struct alloc_context *ac, int order, 174 int alloc_flags); 175 176 extern int kcompactd_run(int nid); 177 extern void kcompactd_stop(int nid); 178 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx); 179 180 #else 181 static inline void reset_isolation_suitable(pg_data_t *pgdat) 182 { 183 } 184 185 static inline enum compact_result compaction_suitable(struct zone *zone, int order, 186 int alloc_flags, int classzone_idx) 187 { 188 return COMPACT_SKIPPED; 189 } 190 191 static inline void defer_compaction(struct zone *zone, int order) 192 { 193 } 194 195 static inline bool compaction_deferred(struct zone *zone, int order) 196 { 197 return true; 198 } 199 200 static inline bool compaction_made_progress(enum compact_result result) 201 { 202 return false; 203 } 204 205 static inline bool compaction_failed(enum compact_result result) 206 { 207 return false; 208 } 209 210 static inline bool compaction_withdrawn(enum compact_result result) 211 { 212 return true; 213 } 214 215 static inline int kcompactd_run(int nid) 216 { 217 return 0; 218 } 219 static inline void kcompactd_stop(int nid) 220 { 221 } 222 223 static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx) 224 { 225 } 226 227 #endif /* CONFIG_COMPACTION */ 228 229 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) 230 struct node; 231 extern int compaction_register_node(struct node *node); 232 extern void compaction_unregister_node(struct node *node); 233 234 #else 235 236 static inline int compaction_register_node(struct node *node) 237 { 238 return 0; 239 } 240 241 static inline void compaction_unregister_node(struct node *node) 242 { 243 } 244 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */ 245 246 #endif /* _LINUX_COMPACTION_H */ 247