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 deferred due to past failures */
   6#define COMPACT_DEFERRED        0
   7/* compaction didn't start as it was not possible or direct reclaim was more suitable */
   8#define COMPACT_SKIPPED         1
   9/* compaction should continue to another pageblock */
  10#define COMPACT_CONTINUE        2
  11/* direct compaction partially compacted a zone and there are suitable pages */
  12#define COMPACT_PARTIAL         3
  13/* The full zone was compacted */
  14#define COMPACT_COMPLETE        4
  15
  16/* Used to signal whether compaction detected need_sched() or lock contention */
  17/* No contention detected */
  18#define COMPACT_CONTENDED_NONE  0
  19/* Either need_sched() was true or fatal signal pending */
  20#define COMPACT_CONTENDED_SCHED 1
  21/* Zone lock or lru_lock was contended in async compaction */
  22#define COMPACT_CONTENDED_LOCK  2
  23
  24#ifdef CONFIG_COMPACTION
  25extern int sysctl_compact_memory;
  26extern int sysctl_compaction_handler(struct ctl_table *table, int write,
  27                        void __user *buffer, size_t *length, loff_t *ppos);
  28extern int sysctl_extfrag_threshold;
  29extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
  30                        void __user *buffer, size_t *length, loff_t *ppos);
  31
  32extern int fragmentation_index(struct zone *zone, unsigned int order);
  33extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
  34                        int order, gfp_t gfp_mask, nodemask_t *mask,
  35                        enum migrate_mode mode, int *contended,
  36                        struct zone **candidate_zone);
  37extern void compact_pgdat(pg_data_t *pgdat, int order);
  38extern void reset_isolation_suitable(pg_data_t *pgdat);
  39extern unsigned long compaction_suitable(struct zone *zone, int order);
  40
  41/* Do not skip compaction more than 64 times */
  42#define COMPACT_MAX_DEFER_SHIFT 6
  43
  44/*
  45 * Compaction is deferred when compaction fails to result in a page
  46 * allocation success. 1 << compact_defer_limit compactions are skipped up
  47 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  48 */
  49static inline void defer_compaction(struct zone *zone, int order)
  50{
  51        zone->compact_considered = 0;
  52        zone->compact_defer_shift++;
  53
  54        if (order < zone->compact_order_failed)
  55                zone->compact_order_failed = order;
  56
  57        if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
  58                zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
  59}
  60
  61/* Returns true if compaction should be skipped this time */
  62static inline bool compaction_deferred(struct zone *zone, int order)
  63{
  64        unsigned long defer_limit = 1UL << zone->compact_defer_shift;
  65
  66        if (order < zone->compact_order_failed)
  67                return false;
  68
  69        /* Avoid possible overflow */
  70        if (++zone->compact_considered > defer_limit)
  71                zone->compact_considered = defer_limit;
  72
  73        return zone->compact_considered < defer_limit;
  74}
  75
  76/*
  77 * Update defer tracking counters after successful compaction of given order,
  78 * which means an allocation either succeeded (alloc_success == true) or is
  79 * expected to succeed.
  80 */
  81static inline void compaction_defer_reset(struct zone *zone, int order,
  82                bool alloc_success)
  83{
  84        if (alloc_success) {
  85                zone->compact_considered = 0;
  86                zone->compact_defer_shift = 0;
  87        }
  88        if (order >= zone->compact_order_failed)
  89                zone->compact_order_failed = order + 1;
  90}
  91
  92/* Returns true if restarting compaction after many failures */
  93static inline bool compaction_restarting(struct zone *zone, int order)
  94{
  95        if (order < zone->compact_order_failed)
  96                return false;
  97
  98        return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
  99                zone->compact_considered >= 1UL << zone->compact_defer_shift;
 100}
 101
 102#else
 103static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
 104                        int order, gfp_t gfp_mask, nodemask_t *nodemask,
 105                        enum migrate_mode mode, int *contended,
 106                        struct zone **candidate_zone)
 107{
 108        return COMPACT_CONTINUE;
 109}
 110
 111static inline void compact_pgdat(pg_data_t *pgdat, int order)
 112{
 113}
 114
 115static inline void reset_isolation_suitable(pg_data_t *pgdat)
 116{
 117}
 118
 119static inline unsigned long compaction_suitable(struct zone *zone, int order)
 120{
 121        return COMPACT_SKIPPED;
 122}
 123
 124static inline void defer_compaction(struct zone *zone, int order)
 125{
 126}
 127
 128static inline bool compaction_deferred(struct zone *zone, int order)
 129{
 130        return true;
 131}
 132
 133#endif /* CONFIG_COMPACTION */
 134
 135#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 136extern int compaction_register_node(struct node *node);
 137extern void compaction_unregister_node(struct node *node);
 138
 139#else
 140
 141static inline int compaction_register_node(struct node *node)
 142{
 143        return 0;
 144}
 145
 146static inline void compaction_unregister_node(struct node *node)
 147{
 148}
 149#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
 150
 151#endif /* _LINUX_COMPACTION_H */
 152