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#define COMPACT_MODE_DIRECT_RECLAIM     0
  15#define COMPACT_MODE_KSWAPD             1
  16
  17#ifdef CONFIG_COMPACTION
  18extern int sysctl_compact_memory;
  19extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  20                        void __user *buffer, size_t *length, loff_t *ppos);
  21extern int sysctl_extfrag_threshold;
  22extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  23                        void __user *buffer, size_t *length, loff_t *ppos);
  24
  25extern int fragmentation_index(struct zone *zone, unsigned int order);
  26extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
  27                        int order, gfp_t gfp_mask, nodemask_t *mask,
  28                        bool sync);
  29extern unsigned long compaction_suitable(struct zone *zone, int order);
  30extern unsigned long compact_zone_order(struct zone *zone, int order,
  31                                        gfp_t gfp_mask, bool sync,
  32                                        int compact_mode);
  33
  34/* Do not skip compaction more than 64 times */
  35#define COMPACT_MAX_DEFER_SHIFT 6
  36
  37/*
  38 * Compaction is deferred when compaction fails to result in a page
  39 * allocation success. 1 << compact_defer_limit compactions are skipped up
  40 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  41 */
  42static inline void defer_compaction(struct zone *zone)
  43{
  44        zone->compact_considered = 0;
  45        zone->compact_defer_shift++;
  46
  47        if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  48                zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  49}
  50
  51/* Returns true if compaction should be skipped this time */
  52static inline bool compaction_deferred(struct zone *zone)
  53{
  54        unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  55
  56        /* Avoid possible overflow */
  57        if (++zone->compact_considered > defer_limit)
  58                zone->compact_considered = defer_limit;
  59
  60        return zone->compact_considered < (1UL << zone->compact_defer_shift);
  61}
  62
  63#else
  64static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
  65                        int order, gfp_t gfp_mask, nodemask_t *nodemask,
  66                        bool sync)
  67{
  68        return COMPACT_CONTINUE;
  69}
  70
  71static inline unsigned long compaction_suitable(struct zone *zone, int order)
  72{
  73        return COMPACT_SKIPPED;
  74}
  75
  76static inline unsigned long compact_zone_order(struct zone *zone, int order,
  77                                               gfp_t gfp_mask, bool sync,
  78                                               int compact_mode)
  79{
  80        return COMPACT_CONTINUE;
  81}
  82
  83static inline void defer_compaction(struct zone *zone)
  84{
  85}
  86
  87static inline bool compaction_deferred(struct zone *zone)
  88{
  89        return 1;
  90}
  91
  92#endif /* CONFIG_COMPACTION */
  93
  94#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
  95extern int compaction_register_node(struct node *node);
  96extern void compaction_unregister_node(struct node *node);
  97
  98#else
  99
 100static inline int compaction_register_node(struct node *node)
 101{
 102        return 0;
 103}
 104
 105static inline void compaction_unregister_node(struct node *node)
 106{
 107}
 108#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 109
 110#endif /* _LINUX_COMPACTION_H */
 111