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