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 deferred due to past failures */
   6 #define COMPACT_DEFERRED        0
   7 /* compaction didn't start as it was not possible or direct reclaim was more suitable */
   8 #define COMPACT_SKIPPED         1
   9 /* compaction should continue to another pageblock */
  10 #define COMPACT_CONTINUE        2
  11 /* direct compaction partially compacted a zone and there are suitable pages */
  12 #define COMPACT_PARTIAL         3
  13 /* The full zone was compacted */
  14 #define COMPACT_COMPLETE        4
  15
  16 #ifdef CONFIG_COMPACTION
  17 extern int sysctl_compact_memory;
  18 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  19                         void __user *buffer, size_t *length, loff_t *ppos);
  20 extern int sysctl_extfrag_threshold;
  21 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  22                         void __user *buffer, size_t *length, loff_t *ppos);
  23
  24 extern int fragmentation_index(struct zone *zone, unsigned int order);
  25 extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
  26                         int order, gfp_t gfp_mask, nodemask_t *mask,
  27                         enum migrate_mode mode, bool *contended,
  28                         struct zone **candidate_zone);
  29 extern void compact_pgdat(pg_data_t *pgdat, int order);
  30 extern void reset_isolation_suitable(pg_data_t *pgdat);
  31 extern unsigned long compaction_suitable(struct zone *zone, int order);
  32
  33 /* Do not skip compaction more than 64 times */
  34 #define COMPACT_MAX_DEFER_SHIFT 6
  35
  36 /*
  37  * Compaction is deferred when compaction fails to result in a page
  38  * allocation success. 1 << compact_defer_limit compactions are skipped up
  39  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  40  */
  41 static inline void defer_compaction(struct zone *zone, int order)
  42 {
  43         zone->compact_considered = 0;
  44         zone->compact_defer_shift++;
  45
  46         if (order < zone->compact_order_failed)
  47                 zone->compact_order_failed = order;
  48
  49         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  50                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  51 }
  52
  53 /* Returns true if compaction should be skipped this time */
  54 static inline bool compaction_deferred(struct zone *zone, int order)
  55 {
  56         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  57
  58         if (order < zone->compact_order_failed)
  59                 return false;
  60
  61         /* Avoid possible overflow */
  62         if (++zone->compact_considered > defer_limit)
  63                 zone->compact_considered = defer_limit;
  64
  65         return zone->compact_considered < defer_limit;
  66 }
  67
  68 /*
  69  * Update defer tracking counters after successful compaction of given order,
  70  * which means an allocation either succeeded (alloc_success == true) or is
  71  * expected to succeed.
  72  */
  73 static inline void compaction_defer_reset(struct zone *zone, int order,
  74                 bool alloc_success)
  75 {
  76         if (alloc_success) {
  77                 zone->compact_considered = 0;
  78                 zone->compact_defer_shift = 0;
  79         }
  80         if (order >= zone->compact_order_failed)
  81                 zone->compact_order_failed = order + 1;
  82 }
  83
  84 /* Returns true if restarting compaction after many failures */
  85 static inline bool compaction_restarting(struct zone *zone, int order)
  86 {
  87         if (order < zone->compact_order_failed)
  88                 return false;
  89
  90         return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
  91                 zone->compact_considered >= 1UL << zone->compact_defer_shift;
  92 }
  93
  94 #else
  95 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  96                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
  97                         enum migrate_mode mode, bool *contended,
  98                         struct zone **candidate_zone)
  99 {
 100         return COMPACT_CONTINUE;
 101 }
 102
 103 static inline void compact_pgdat(pg_data_t *pgdat, int order)
 104 {
 105 }
 106
 107 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 108 {
 109 }
 110
 111 static inline unsigned long compaction_suitable(struct zone *zone, int order)
 112 {
 113         return COMPACT_SKIPPED;
 114 }
 115
 116 static inline void defer_compaction(struct zone *zone, int order)
 117 {
 118 }
 119
 120 static inline bool compaction_deferred(struct zone *zone, int order)
 121 {
 122         return true;
 123 }
 124
 125 #endif /* CONFIG_COMPACTION */
 126
 127 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 128 extern int compaction_register_node(struct node *node);
 129 extern void compaction_unregister_node(struct node *node);
 130
 131 #else
 132
 133 static inline int compaction_register_node(struct node *node)
 134 {
 135         return 0;
 136 }
 137
 138 static inline void compaction_unregister_node(struct node *node)
 139 {
 140 }
 141 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 142
 143 #endif /* _LINUX_COMPACTION_H */