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 sysctl_compact_memory;
  58 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  59                         void __user *buffer, size_t *length, loff_t *ppos);
  60 extern int sysctl_extfrag_threshold;
  61 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  62                         void __user *buffer, size_t *length, loff_t *ppos);
  63 extern int sysctl_compact_unevictable_allowed;
  64
  65 extern int fragmentation_index(struct zone *zone, unsigned int order);
  66 extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
  67                         unsigned int order,
  68                 unsigned int alloc_flags, const struct alloc_context *ac,
  69                 enum migrate_mode mode, int *contended);
  70 extern void compact_pgdat(pg_data_t *pgdat, int order);
  71 extern void reset_isolation_suitable(pg_data_t *pgdat);
  72 extern enum compact_result compaction_suitable(struct zone *zone, int order,
  73                 unsigned int alloc_flags, int classzone_idx);
  74
  75 extern void defer_compaction(struct zone *zone, int order);
  76 extern bool compaction_deferred(struct zone *zone, int order);
  77 extern void compaction_defer_reset(struct zone *zone, int order,
  78                                 bool alloc_success);
  79 extern bool compaction_restarting(struct zone *zone, int order);
  80
  81 /* Compaction has made some progress and retrying makes sense */
  82 static inline bool compaction_made_progress(enum compact_result result)
  83 {
  84         /*
  85          * Even though this might sound confusing this in fact tells us
  86          * that the compaction successfully isolated and migrated some
  87          * pageblocks.
  88          */
  89         if (result == COMPACT_PARTIAL)
  90                 return true;
  91
  92         return false;
  93 }
  94
  95 /* Compaction has failed and it doesn't make much sense to keep retrying. */
  96 static inline bool compaction_failed(enum compact_result result)
  97 {
  98         /* All zones were scanned completely and still not result. */
  99         if (result == COMPACT_COMPLETE)
 100                 return true;
 101
 102         return false;
 103 }
 104
 105 /*
 106  * Compaction  has backed off for some reason. It might be throttling or
 107  * lock contention. Retrying is still worthwhile.
 108  */
 109 static inline bool compaction_withdrawn(enum compact_result result)
 110 {
 111         /*
 112          * Compaction backed off due to watermark checks for order-0
 113          * so the regular reclaim has to try harder and reclaim something.
 114          */
 115         if (result == COMPACT_SKIPPED)
 116                 return true;
 117
 118         /*
 119          * If compaction is deferred for high-order allocations, it is
 120          * because sync compaction recently failed. If this is the case
 121          * and the caller requested a THP allocation, we do not want
 122          * to heavily disrupt the system, so we fail the allocation
 123          * instead of entering direct reclaim.
 124          */
 125         if (result == COMPACT_DEFERRED)
 126                 return true;
 127
 128         /*
 129          * If compaction in async mode encounters contention or blocks higher
 130          * priority task we back off early rather than cause stalls.
 131          */
 132         if (result == COMPACT_CONTENDED)
 133                 return true;
 134
 135         /*
 136          * Page scanners have met but we haven't scanned full zones so this
 137          * is a back off in fact.
 138          */
 139         if (result == COMPACT_PARTIAL_SKIPPED)
 140                 return true;
 141
 142         return false;
 143 }
 144
 145
 146 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 147                                         int alloc_flags);
 148
 149 extern int kcompactd_run(int nid);
 150 extern void kcompactd_stop(int nid);
 151 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
 152
 153 #else
 154 static inline enum compact_result try_to_compact_pages(gfp_t gfp_mask,
 155                         unsigned int order, int alloc_flags,
 156                         const struct alloc_context *ac,
 157                         enum migrate_mode mode, int *contended)
 158 {
 159         return COMPACT_CONTINUE;
 160 }
 161
 162 static inline void compact_pgdat(pg_data_t *pgdat, int order)
 163 {
 164 }
 165
 166 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 167 {
 168 }
 169
 170 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
 171                                         int alloc_flags, int classzone_idx)
 172 {
 173         return COMPACT_SKIPPED;
 174 }
 175
 176 static inline void defer_compaction(struct zone *zone, int order)
 177 {
 178 }
 179
 180 static inline bool compaction_deferred(struct zone *zone, int order)
 181 {
 182         return true;
 183 }
 184
 185 static inline bool compaction_made_progress(enum compact_result result)
 186 {
 187         return false;
 188 }
 189
 190 static inline bool compaction_failed(enum compact_result result)
 191 {
 192         return false;
 193 }
 194
 195 static inline bool compaction_withdrawn(enum compact_result result)
 196 {
 197         return true;
 198 }
 199
 200 static inline int kcompactd_run(int nid)
 201 {
 202         return 0;
 203 }
 204 static inline void kcompactd_stop(int nid)
 205 {
 206 }
 207
 208 static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
 209 {
 210 }
 211
 212 #endif /* CONFIG_COMPACTION */
 213
 214 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 215 extern int compaction_register_node(struct node *node);
 216 extern void compaction_unregister_node(struct node *node);
 217
 218 #else
 219
 220 static inline int compaction_register_node(struct node *node)
 221 {
 222         return 0;
 223 }
 224
 225 static inline void compaction_unregister_node(struct node *node)
 226 {
 227 }
 228 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 229
 230 #endif /* _LINUX_COMPACTION_H */