include/linux/compaction.h

   1 #ifndef _LINUX_COMPACTION_H
   2 #define _LINUX_COMPACTION_H
   3
   4 /* Return values for compact_zone() and try_to_compact_pages() */
   5 /* When adding new states, please adjust include/trace/events/compaction.h */
   6 enum compact_result {
   7         /* For more detailed tracepoint output - internal to compaction */
   8         COMPACT_NOT_SUITABLE_ZONE,
   9         /*
  10          * compaction didn't start as it was not possible or direct reclaim
  11          * was more suitable
  12          */
  13         COMPACT_SKIPPED,
  14         /* compaction didn't start as it was deferred due to past failures */
  15         COMPACT_DEFERRED,
  16
  17         /* compaction not active last round */
  18         COMPACT_INACTIVE = COMPACT_DEFERRED,
  19
  20         /* For more detailed tracepoint output - internal to compaction */
  21         COMPACT_NO_SUITABLE_PAGE,
  22         /* compaction should continue to another pageblock */
  23         COMPACT_CONTINUE,
  24
  25         /*
  26          * The full zone was compacted scanned but wasn't successfull to compact
  27          * suitable pages.
  28          */
  29         COMPACT_COMPLETE,
  30         /*
  31          * direct compaction has scanned part of the zone but wasn't successfull
  32          * to compact suitable pages.
  33          */
  34         COMPACT_PARTIAL_SKIPPED,
  35
  36         /* compaction terminated prematurely due to lock contentions */
  37         COMPACT_CONTENDED,
  38
  39         /*
  40          * direct compaction partially compacted a zone and there might be
  41          * suitable pages
  42          */
  43         COMPACT_PARTIAL,
  44 };
  45
  46 /* Used to signal whether compaction detected need_sched() or lock contention */
  47 /* No contention detected */
  48 #define COMPACT_CONTENDED_NONE  0
  49 /* Either need_sched() was true or fatal signal pending */
  50 #define COMPACT_CONTENDED_SCHED 1
  51 /* Zone lock or lru_lock was contended in async compaction */
  52 #define COMPACT_CONTENDED_LOCK  2
  53
  54 struct alloc_context; /* in mm/internal.h */
  55
  56 #ifdef CONFIG_COMPACTION
  57 extern int PageMovable(struct page *page);
  58 extern void __SetPageMovable(struct page *page, struct address_space *mapping);
  59 extern void __ClearPageMovable(struct page *page);
  60 extern int sysctl_compact_memory;
  61 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  62                         void __user *buffer, size_t *length, loff_t *ppos);
  63 extern int sysctl_extfrag_threshold;
  64 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  65                         void __user *buffer, size_t *length, loff_t *ppos);
  66 extern int sysctl_compact_unevictable_allowed;
  67
  68 extern int fragmentation_index(struct zone *zone, unsigned int order);
  69 extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
  70                         unsigned int order,
  71                 unsigned int alloc_flags, const struct alloc_context *ac,
  72                 enum migrate_mode mode, int *contended);
  73 extern void compact_pgdat(pg_data_t *pgdat, int order);
  74 extern void reset_isolation_suitable(pg_data_t *pgdat);
  75 extern enum compact_result compaction_suitable(struct zone *zone, int order,
  76                 unsigned int alloc_flags, int classzone_idx);
  77
  78 extern void defer_compaction(struct zone *zone, int order);
  79 extern bool compaction_deferred(struct zone *zone, int order);
  80 extern void compaction_defer_reset(struct zone *zone, int order,
  81                                 bool alloc_success);
  82 extern bool compaction_restarting(struct zone *zone, int order);
  83
  84 /* Compaction has made some progress and retrying makes sense */
  85 static 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. */
  99 static 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  */
 112 static 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
 149 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 150                                         int alloc_flags);
 151
 152 extern int kcompactd_run(int nid);
 153 extern void kcompactd_stop(int nid);
 154 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
 155
 156 #else
 157 static inline int PageMovable(struct page *page)
 158 {
 159         return 0;
 160 }
 161 static inline void __SetPageMovable(struct page *page,
 162                         struct address_space *mapping)
 163 {
 164 }
 165
 166 static inline void __ClearPageMovable(struct page *page)
 167 {
 168 }
 169
 170 static inline enum compact_result try_to_compact_pages(gfp_t gfp_mask,
 171                         unsigned int order, int alloc_flags,
 172                         const struct alloc_context *ac,
 173                         enum migrate_mode mode, int *contended)
 174 {
 175         return COMPACT_CONTINUE;
 176 }
 177
 178 static inline void compact_pgdat(pg_data_t *pgdat, int order)
 179 {
 180 }
 181
 182 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 183 {
 184 }
 185
 186 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
 187                                         int alloc_flags, int classzone_idx)
 188 {
 189         return COMPACT_SKIPPED;
 190 }
 191
 192 static inline void defer_compaction(struct zone *zone, int order)
 193 {
 194 }
 195
 196 static inline bool compaction_deferred(struct zone *zone, int order)
 197 {
 198         return true;
 199 }
 200
 201 static inline bool compaction_made_progress(enum compact_result result)
 202 {
 203         return false;
 204 }
 205
 206 static inline bool compaction_failed(enum compact_result result)
 207 {
 208         return false;
 209 }
 210
 211 static inline bool compaction_withdrawn(enum compact_result result)
 212 {
 213         return true;
 214 }
 215
 216 static inline int kcompactd_run(int nid)
 217 {
 218         return 0;
 219 }
 220 static inline void kcompactd_stop(int nid)
 221 {
 222 }
 223
 224 static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
 225 {
 226 }
 227
 228 #endif /* CONFIG_COMPACTION */
 229
 230 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 231 struct node;
 232 extern int compaction_register_node(struct node *node);
 233 extern void compaction_unregister_node(struct node *node);
 234
 235 #else
 236
 237 static inline int compaction_register_node(struct node *node)
 238 {
 239         return 0;
 240 }
 241
 242 static inline void compaction_unregister_node(struct node *node)
 243 {
 244 }
 245 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 246
 247 #endif /* _LINUX_COMPACTION_H */