linux/include/linux/compaction.h
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   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, bool *contended);
  26extern int compact_pgdat(pg_data_t *pgdat, int order);
  27extern unsigned long compaction_suitable(struct zone *zone, int order);
  28
  29/* Do not skip compaction more than 64 times */
  30#define COMPACT_MAX_DEFER_SHIFT 6
  31
  32/*
  33 * Compaction is deferred when compaction fails to result in a page
  34 * allocation success. 1 << compact_defer_limit compactions are skipped up
  35 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  36 */
  37static inline void defer_compaction(struct zone *zone, int order)
  38{
  39        zone->compact_considered = 0;
  40        zone->compact_defer_shift++;
  41
  42        if (order < zone->compact_order_failed)
  43                zone->compact_order_failed = order;
  44
  45        if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  46                zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  47}
  48
  49/* Returns true if compaction should be skipped this time */
  50static inline bool compaction_deferred(struct zone *zone, int order)
  51{
  52        unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  53
  54        if (order < zone->compact_order_failed)
  55                return false;
  56
  57        /* Avoid possible overflow */
  58        if (++zone->compact_considered > defer_limit)
  59                zone->compact_considered = defer_limit;
  60
  61        return zone->compact_considered < defer_limit;
  62}
  63
  64#else
  65static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  66                        int order, gfp_t gfp_mask, nodemask_t *nodemask,
  67                        bool sync, bool *contended)
  68{
  69        return COMPACT_CONTINUE;
  70}
  71
  72static inline int compact_pgdat(pg_data_t *pgdat, int order)
  73{
  74        return COMPACT_CONTINUE;
  75}
  76
  77static inline unsigned long compaction_suitable(struct zone *zone, int order)
  78{
  79        return COMPACT_SKIPPED;
  80}
  81
  82static inline void defer_compaction(struct zone *zone, int order)
  83{
  84}
  85
  86static inline bool compaction_deferred(struct zone *zone, int order)
  87{
  88        return true;
  89}
  90
  91#endif /* CONFIG_COMPACTION */
  92
  93#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
  94extern int compaction_register_node(struct node *node);
  95extern void compaction_unregister_node(struct node *node);
  96
  97#else
  98
  99static inline int compaction_register_node(struct node *node)
 100{
 101        return 0;
 102}
 103
 104static inline void compaction_unregister_node(struct node *node)
 105{
 106}
 107#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 108
 109#endif /* _LINUX_COMPACTION_H */
 110
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