#ifndef _LINUX_COMPACTION_H
  #define _LINUX_COMPACTION_H

  /* Return values for compact_zone() and try_to_compact_pages() */
  /* compaction didn't start as it was not possible or direct reclaim was more suitable */
  #define COMPACT_SKIPPED		0
  /* compaction should continue to another pageblock */
  #define COMPACT_CONTINUE	1
  /* direct compaction partially compacted a zone and there are suitable pages */
  #define COMPACT_PARTIAL		2
  /* The full zone was compacted */
  #define COMPACT_COMPLETE	3

  #ifdef CONFIG_COMPACTION
  extern int sysctl_compact_memory;
  extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  			void __user *buffer, size_t *length, loff_t *ppos);

  extern int sysctl_extfrag_threshold;
  extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  			void __user *buffer, size_t *length, loff_t *ppos);

  
  extern int fragmentation_index(struct zone *zone, unsigned int order);
  extern unsigned long try_to_compact_pages(struct zonelist *zonelist,

  			int order, gfp_t gfp_mask, nodemask_t *mask,
  			bool sync);

  extern unsigned long compaction_suitable(struct zone *zone, int order);

  
  /* Do not skip compaction more than 64 times */
  #define COMPACT_MAX_DEFER_SHIFT 6
  
  /*
   * Compaction is deferred when compaction fails to result in a page
   * allocation success. 1 << compact_defer_limit compactions are skipped up
   * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
   */
  static inline void defer_compaction(struct zone *zone)
  {
  	zone->compact_considered = 0;
  	zone->compact_defer_shift++;
  
  	if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  		zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  }
  
  /* Returns true if compaction should be skipped this time */
  static inline bool compaction_deferred(struct zone *zone)
  {
  	unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  
  	/* Avoid possible overflow */
  	if (++zone->compact_considered > defer_limit)
  		zone->compact_considered = defer_limit;
  
  	return zone->compact_considered < (1UL << zone->compact_defer_shift);
  }

  #else
  static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,

  			int order, gfp_t gfp_mask, nodemask_t *nodemask,
  			bool sync)

  {
  	return COMPACT_CONTINUE;
  }

  static inline unsigned long compaction_suitable(struct zone *zone, int order)
  {
  	return COMPACT_SKIPPED;
  }

  static inline void defer_compaction(struct zone *zone)
  {
  }
  
  static inline bool compaction_deferred(struct zone *zone)
  {
  	return 1;
  }

  #endif /* CONFIG_COMPACTION */

  #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
  extern int compaction_register_node(struct node *node);
  extern void compaction_unregister_node(struct node *node);
  
  #else
  
  static inline int compaction_register_node(struct node *node)
  {
  	return 0;
  }
  
  static inline void compaction_unregister_node(struct node *node)
  {
  }
  #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */

  #endif /* _LINUX_COMPACTION_H */