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                         bool sync);
  26 extern unsigned long compaction_suitable(struct zone *zone, int order);
  27
  28 /* Do not skip compaction more than 64 times */
  29 #define COMPACT_MAX_DEFER_SHIFT 6
  30
  31 /*
  32  * Compaction is deferred when compaction fails to result in a page
  33  * allocation success. 1 << compact_defer_limit compactions are skipped up
  34  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  35  */
  36 static inline void defer_compaction(struct zone *zone)
  37 {
  38         zone->compact_considered = 0;
  39         zone->compact_defer_shift++;
  40
  41         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  42                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  43 }
  44
  45 /* Returns true if compaction should be skipped this time */
  46 static inline bool compaction_deferred(struct zone *zone)
  47 {
  48         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  49
  50         /* Avoid possible overflow */
  51         if (++zone->compact_considered > defer_limit)
  52                 zone->compact_considered = defer_limit;
  53
  54         return zone->compact_considered < (1UL << zone->compact_defer_shift);
  55 }
  56
  57 #else
  58 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  59                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
  60                         bool sync)
  61 {
  62         return COMPACT_CONTINUE;
  63 }
  64
  65 static inline unsigned long compaction_suitable(struct zone *zone, int order)
  66 {
  67         return COMPACT_SKIPPED;
  68 }
  69
  70 static inline void defer_compaction(struct zone *zone)
  71 {
  72 }
  73
  74 static inline bool compaction_deferred(struct zone *zone)
  75 {
  76         return 1;
  77 }
  78
  79 #endif /* CONFIG_COMPACTION */
  80
  81 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
  82 extern int compaction_register_node(struct node *node);
  83 extern void compaction_unregister_node(struct node *node);
  84
  85 #else
  86
  87 static inline int compaction_register_node(struct node *node)
  88 {
  89         return 0;
  90 }
  91
  92 static inline void compaction_unregister_node(struct node *node)
  93 {
  94 }
  95 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
  96
  97 #endif /* _LINUX_COMPACTION_H */