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                         struct zone **candidate_zone);
  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
  41 /* Do not skip compaction more than 64 times */
  42 #define COMPACT_MAX_DEFER_SHIFT 6
  43
  44 /*
  45  * Compaction is deferred when compaction fails to result in a page
  46  * allocation success. 1 << compact_defer_limit compactions are skipped up
  47  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  48  */
  49 static inline void defer_compaction(struct zone *zone, int order)
  50 {
  51         zone->compact_considered = 0;
  52         zone->compact_defer_shift++;
  53
  54         if (order < zone->compact_order_failed)
  55                 zone->compact_order_failed = order;
  56
  57         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  58                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  59 }
  60
  61 /* Returns true if compaction should be skipped this time */
  62 static inline bool compaction_deferred(struct zone *zone, int order)
  63 {
  64         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  65
  66         if (order < zone->compact_order_failed)
  67                 return false;
  68
  69         /* Avoid possible overflow */
  70         if (++zone->compact_considered > defer_limit)
  71                 zone->compact_considered = defer_limit;
  72
  73         return zone->compact_considered < defer_limit;
  74 }
  75
  76 /*
  77  * Update defer tracking counters after successful compaction of given order,
  78  * which means an allocation either succeeded (alloc_success == true) or is
  79  * expected to succeed.
  80  */
  81 static inline void compaction_defer_reset(struct zone *zone, int order,
  82                 bool alloc_success)
  83 {
  84         if (alloc_success) {
  85                 zone->compact_considered = 0;
  86                 zone->compact_defer_shift = 0;
  87         }
  88         if (order >= zone->compact_order_failed)
  89                 zone->compact_order_failed = order + 1;
  90 }
  91
  92 /* Returns true if restarting compaction after many failures */
  93 static inline bool compaction_restarting(struct zone *zone, int order)
  94 {
  95         if (order < zone->compact_order_failed)
  96                 return false;
  97
  98         return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
  99                 zone->compact_considered >= 1UL << zone->compact_defer_shift;
 100 }
 101
 102 #else
 103 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
 104                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
 105                         enum migrate_mode mode, int *contended,
 106                         struct zone **candidate_zone)
 107 {
 108         return COMPACT_CONTINUE;
 109 }
 110
 111 static inline void compact_pgdat(pg_data_t *pgdat, int order)
 112 {
 113 }
 114
 115 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 116 {
 117 }
 118
 119 static inline unsigned long compaction_suitable(struct zone *zone, int order)
 120 {
 121         return COMPACT_SKIPPED;
 122 }
 123
 124 static inline void defer_compaction(struct zone *zone, int order)
 125 {
 126 }
 127
 128 static inline bool compaction_deferred(struct zone *zone, int order)
 129 {
 130         return true;
 131 }
 132
 133 #endif /* CONFIG_COMPACTION */
 134
 135 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 136 extern int compaction_register_node(struct node *node);
 137 extern void compaction_unregister_node(struct node *node);
 138
 139 #else
 140
 141 static inline int compaction_register_node(struct node *node)
 142 {
 143         return 0;
 144 }
 145
 146 static inline void compaction_unregister_node(struct node *node)
 147 {
 148 }
 149 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 150
 151 #endif /* _LINUX_COMPACTION_H */