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                         enum migrate_mode mode, bool *contended);
  26 extern void compact_pgdat(pg_data_t *pgdat, int order);
  27 extern void reset_isolation_suitable(pg_data_t *pgdat);
  28 extern unsigned long compaction_suitable(struct zone *zone, int order);
  29
  30 /* Do not skip compaction more than 64 times */
  31 #define COMPACT_MAX_DEFER_SHIFT 6
  32
  33 /*
  34  * Compaction is deferred when compaction fails to result in a page
  35  * allocation success. 1 << compact_defer_limit compactions are skipped up
  36  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  37  */
  38 static inline void defer_compaction(struct zone *zone, int order)
  39 {
  40         zone->compact_considered = 0;
  41         zone->compact_defer_shift++;
  42
  43         if (order < zone->compact_order_failed)
  44                 zone->compact_order_failed = order;
  45
  46         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  47                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  48 }
  49
  50 /* Returns true if compaction should be skipped this time */
  51 static inline bool compaction_deferred(struct zone *zone, int order)
  52 {
  53         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  54
  55         if (order < zone->compact_order_failed)
  56                 return false;
  57
  58         /* Avoid possible overflow */
  59         if (++zone->compact_considered > defer_limit)
  60                 zone->compact_considered = defer_limit;
  61
  62         return zone->compact_considered < defer_limit;
  63 }
  64
  65 /*
  66  * Update defer tracking counters after successful compaction of given order,
  67  * which means an allocation either succeeded (alloc_success == true) or is
  68  * expected to succeed.
  69  */
  70 static inline void compaction_defer_reset(struct zone *zone, int order,
  71                 bool alloc_success)
  72 {
  73         if (alloc_success) {
  74                 zone->compact_considered = 0;
  75                 zone->compact_defer_shift = 0;
  76         }
  77         if (order >= zone->compact_order_failed)
  78                 zone->compact_order_failed = order + 1;
  79 }
  80
  81 /* Returns true if restarting compaction after many failures */
  82 static inline bool compaction_restarting(struct zone *zone, int order)
  83 {
  84         if (order < zone->compact_order_failed)
  85                 return false;
  86
  87         return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
  88                 zone->compact_considered >= 1UL << zone->compact_defer_shift;
  89 }
  90
  91 #else
  92 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  93                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
  94                         enum migrate_mode mode, bool *contended)
  95 {
  96         return COMPACT_CONTINUE;
  97 }
  98
  99 static inline void compact_pgdat(pg_data_t *pgdat, int order)
 100 {
 101 }
 102
 103 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 104 {
 105 }
 106
 107 static inline unsigned long compaction_suitable(struct zone *zone, int order)
 108 {
 109         return COMPACT_SKIPPED;
 110 }
 111
 112 static inline void defer_compaction(struct zone *zone, int order)
 113 {
 114 }
 115
 116 static inline bool compaction_deferred(struct zone *zone, int order)
 117 {
 118         return true;
 119 }
 120
 121 #endif /* CONFIG_COMPACTION */
 122
 123 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 124 extern int compaction_register_node(struct node *node);
 125 extern void compaction_unregister_node(struct node *node);
 126
 127 #else
 128
 129 static inline int compaction_register_node(struct node *node)
 130 {
 131         return 0;
 132 }
 133
 134 static inline void compaction_unregister_node(struct node *node)
 135 {
 136 }
 137 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 138
 139 #endif /* _LINUX_COMPACTION_H */