LXR linux/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
  15extern int sysctl_compact_memory;
  16extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  17                        void __user *buffer, size_t *length, loff_t *ppos);
  18extern int sysctl_extfrag_threshold;
  19extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  20                        void __user *buffer, size_t *length, loff_t *ppos);
  21
  22extern int fragmentation_index(struct zone *zone, unsigned int order);
  23extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
  24                        int order, gfp_t gfp_mask, nodemask_t *mask,
  25                        bool sync);
  26extern 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 */
  36static 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 */
  46static 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
  58static 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
  65static inline unsigned long compaction_suitable(struct zone *zone, int order)
  66{
  67        return COMPACT_SKIPPED;
  68}
  69
  70static inline void defer_compaction(struct zone *zone)
  71{
  72}
  73
  74static 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)
  82extern int compaction_register_node(struct node *node);
  83extern void compaction_unregister_node(struct node *node);
  84
  85#else
  86
  87static inline int compaction_register_node(struct node *node)
  88{
  89        return 0;
  90}
  91
  92static inline void compaction_unregister_node(struct node *node)
  93{
  94}
  95#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
  96
  97#endif /* _LINUX_COMPACTION_H */
  98