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 extern unsigned long compact_zone_order(struct zone *zone, int order,
  28                                         gfp_t gfp_mask, bool sync);
  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)
  39 {
  40         zone->compact_considered = 0;
  41         zone->compact_defer_shift++;
  42
  43         if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  44                 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  45 }
  46
  47 /* Returns true if compaction should be skipped this time */
  48 static inline bool compaction_deferred(struct zone *zone)
  49 {
  50         unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  51
  52         /* Avoid possible overflow */
  53         if (++zone->compact_considered > defer_limit)
  54                 zone->compact_considered = defer_limit;
  55
  56         return zone->compact_considered < (1UL << zone->compact_defer_shift);
  57 }
  58
  59 #else
  60 static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  61                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
  62                         bool sync)
  63 {
  64         return COMPACT_CONTINUE;
  65 }
  66
  67 static inline unsigned long compaction_suitable(struct zone *zone, int order)
  68 {
  69         return COMPACT_SKIPPED;
  70 }
  71
  72 static inline unsigned long compact_zone_order(struct zone *zone, int order,
  73                                                gfp_t gfp_mask, bool sync)
  74 {
  75         return COMPACT_CONTINUE;
  76 }
  77
  78 static inline void defer_compaction(struct zone *zone)
  79 {
  80 }
  81
  82 static inline bool compaction_deferred(struct zone *zone)
  83 {
  84         return 1;
  85 }
  86
  87 #endif /* CONFIG_COMPACTION */
  88
  89 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
  90 extern int compaction_register_node(struct node *node);
  91 extern void compaction_unregister_node(struct node *node);
  92
  93 #else
  94
  95 static inline int compaction_register_node(struct node *node)
  96 {
  97         return 0;
  98 }
  99
 100 static inline void compaction_unregister_node(struct node *node)
 101 {
 102 }
 103 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 104
 105 #endif /* _LINUX_COMPACTION_H */