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 /* Used to signal whether compaction detected need_sched() or lock contention */
  17 /* No contention detected */
  18 #define COMPACT_CONTENDED_NONE  0
  19 /* Either need_sched() was true or fatal signal pending */
  20 #define COMPACT_CONTENDED_SCHED 1
  21 /* Zone lock or lru_lock was contended in async compaction */
  22 #define COMPACT_CONTENDED_LOCK  2
  23
  24 #ifdef CONFIG_COMPACTION
  25 extern int sysctl_compact_memory;
  26 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  27                         void __user *buffer, size_t *length, loff_t *ppos);
  28 extern int sysctl_extfrag_threshold;
  29 extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  30                         void __user *buffer, size_t *length, loff_t *ppos);
  31
  32 extern int fragmentation_index(struct zone *zone, unsigned int order);
  33 extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
  34                         int order, gfp_t gfp_mask, nodemask_t *mask,
  35                         enum migrate_mode mode, int *contended,
  36                         int alloc_flags, int classzone_idx);
  37 extern void compact_pgdat(pg_data_t *pgdat, int order);
  38 extern void reset_isolation_suitable(pg_data_t *pgdat);
  39 extern unsigned long compaction_suitable(struct zone *zone, int order,
  40                                         int alloc_flags, int classzone_idx);
  41
  42 /* Do not skip compaction more than 64 times */
  43 #define COMPACT_MAX_DEFER_SHIFT 6
  44
  45 /*
  46  * Compaction is deferred when compaction fails to result in a page
  47  * allocation success. 1 << compact_defer_limit compactions are skipped up
  48  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  49  */
  50 static inline void defer_compaction(struct zone *zone, int order)
  51 {
  52         zone->compact_considered = 0;
  53         zone->compact_defer_shift++;
  54
  55         if (order < zone->compact_order_failed)
  56                 zone->compact_order_failed = order;
  57
  58         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  59                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  60 }
  61
  62 /* Returns true if compaction should be skipped this time */
  63 static inline bool compaction_deferred(struct zone *zone, int order)
  64 {
  65         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  66
  67         if (order < zone->compact_order_failed)
  68                 return false;
  69
  70         /* Avoid possible overflow */
  71         if (++zone->compact_considered > defer_limit)
  72                 zone->compact_considered = defer_limit;
  73
  74         return zone->compact_considered < defer_limit;
  75 }
  76
  77 /*
  78  * Update defer tracking counters after successful compaction of given order,
  79  * which means an allocation either succeeded (alloc_success == true) or is
  80  * expected to succeed.
  81  */
  82 static inline void compaction_defer_reset(struct zone *zone, int order,
  83                 bool alloc_success)
  84 {
  85         if (alloc_success) {
  86                 zone->compact_considered = 0;
  87                 zone->compact_defer_shift = 0;
  88         }
  89         if (order >= zone->compact_order_failed)
  90                 zone->compact_order_failed = order + 1;
  91 }
  92
  93 /* Returns true if restarting compaction after many failures */
  94 static inline bool compaction_restarting(struct zone *zone, int order)
  95 {
  96         if (order < zone->compact_order_failed)
  97                 return false;
  98
  99         return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
 100                 zone->compact_considered >= 1UL << zone->compact_defer_shift;
 101 }
 102
 103 #else
 104 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
 105                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
 106                         enum migrate_mode mode, int *contended,
 107                         int alloc_flags, int classzone_idx)
 108 {
 109         return COMPACT_CONTINUE;
 110 }
 111
 112 static inline void compact_pgdat(pg_data_t *pgdat, int order)
 113 {
 114 }
 115
 116 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 117 {
 118 }
 119
 120 static inline unsigned long compaction_suitable(struct zone *zone, int order,
 121                                         int alloc_flags, int classzone_idx)
 122 {
 123         return COMPACT_SKIPPED;
 124 }
 125
 126 static inline void defer_compaction(struct zone *zone, int order)
 127 {
 128 }
 129
 130 static inline bool compaction_deferred(struct zone *zone, int order)
 131 {
 132         return true;
 133 }
 134
 135 #endif /* CONFIG_COMPACTION */
 136
 137 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 138 extern int compaction_register_node(struct node *node);
 139 extern void compaction_unregister_node(struct node *node);
 140
 141 #else
 142
 143 static inline int compaction_register_node(struct node *node)
 144 {
 145         return 0;
 146 }
 147
 148 static inline void compaction_unregister_node(struct node *node)
 149 {
 150 }
 151 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 152
 153 #endif /* _LINUX_COMPACTION_H */