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 /* compaction didn't start as it was not possible or direct reclaim was more suitable */
   6 #define COMPACT_SKIPPED         0
   7 /* compaction should continue to another pageblock */
   8 #define COMPACT_CONTINUE        1
   9 /* direct compaction partially compacted a zone and there are suitable pages */
  10 #define COMPACT_PARTIAL         2
  11 /* The full zone was compacted */
  12 #define COMPACT_COMPLETE        3
  13
  14 #ifdef CONFIG_COMPACTION
  15 extern int sysctl_compact_memory;
  16 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  17                         void __user *buffer, size_t *length, loff_t *ppos);
  18 extern int sysctl_extfrag_threshold;
  19 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  20                         void __user *buffer, size_t *length, loff_t *ppos);
  21
  22 extern int fragmentation_index(struct zone *zone, unsigned int order);
  23 extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
  24                         int order, gfp_t gfp_mask, nodemask_t *mask,
  25                         bool sync);
  26 extern int compact_pgdat(pg_data_t *pgdat, int order);
  27 extern unsigned long compaction_suitable(struct zone *zone, int order);
  28
  29 /* Do not skip compaction more than 64 times */
  30 #define COMPACT_MAX_DEFER_SHIFT 6
  31
  32 /*
  33  * Compaction is deferred when compaction fails to result in a page
  34  * allocation success. 1 << compact_defer_limit compactions are skipped up
  35  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  36  */
  37 static inline void defer_compaction(struct zone *zone, int order)
  38 {
  39         zone->compact_considered = 0;
  40         zone->compact_defer_shift++;
  41
  42         if (order < zone->compact_order_failed)
  43                 zone->compact_order_failed = order;
  44
  45         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  46                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  47 }
  48
  49 /* Returns true if compaction should be skipped this time */
  50 static inline bool compaction_deferred(struct zone *zone, int order)
  51 {
  52         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  53
  54         if (order < zone->compact_order_failed)
  55                 return false;
  56
  57         /* Avoid possible overflow */
  58         if (++zone->compact_considered > defer_limit)
  59                 zone->compact_considered = defer_limit;
  60
  61         return zone->compact_considered < (1UL << zone->compact_defer_shift);
  62 }
  63
  64 #else
  65 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  66                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
  67                         bool sync)
  68 {
  69         return COMPACT_CONTINUE;
  70 }
  71
  72 static inline int compact_pgdat(pg_data_t *pgdat, int order)
  73 {
  74         return COMPACT_CONTINUE;
  75 }
  76
  77 static inline unsigned long compaction_suitable(struct zone *zone, int order)
  78 {
  79         return COMPACT_SKIPPED;
  80 }
  81
  82 static inline void defer_compaction(struct zone *zone, int order)
  83 {
  84 }
  85
  86 static inline bool compaction_deferred(struct zone *zone, int order)
  87 {
  88         return 1;
  89 }
  90
  91 #endif /* CONFIG_COMPACTION */
  92
  93 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
  94 extern int compaction_register_node(struct node *node);
  95 extern void compaction_unregister_node(struct node *node);
  96
  97 #else
  98
  99 static inline int compaction_register_node(struct node *node)
 100 {
 101         return 0;
 102 }
 103
 104 static inline void compaction_unregister_node(struct node *node)
 105 {
 106 }
 107 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 108
 109 #endif /* _LINUX_COMPACTION_H */