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