block/blk-wbt.h

   1 #ifndef WB_THROTTLE_H
   2 #define WB_THROTTLE_H
   3
   4 #include <linux/kernel.h>
   5 #include <linux/atomic.h>
   6 #include <linux/wait.h>
   7 #include <linux/timer.h>
   8 #include <linux/ktime.h>
   9
  10 #include "blk-stat.h"
  11
  12 enum wbt_flags {
  13         WBT_TRACKED             = 1,    /* write, tracked for throttling */
  14         WBT_READ                = 2,    /* read */
  15         WBT_KSWAPD              = 4,    /* write, from kswapd */
  16
  17         WBT_NR_BITS             = 3,    /* number of bits */
  18 };
  19
  20 enum {
  21         WBT_NUM_RWQ             = 2,
  22 };
  23
  24 /*
  25  * Enable states. Either off, or on by default (done at init time),
  26  * or on through manual setup in sysfs.
  27  */
  28 enum {
  29         WBT_STATE_ON_DEFAULT    = 1,
  30         WBT_STATE_ON_MANUAL     = 2,
  31 };
  32
  33 static inline void wbt_clear_state(struct blk_issue_stat *stat)
  34 {
  35         stat->time &= BLK_STAT_TIME_MASK;
  36 }
  37
  38 static inline enum wbt_flags wbt_stat_to_mask(struct blk_issue_stat *stat)
  39 {
  40         return (stat->time & BLK_STAT_MASK) >> BLK_STAT_SHIFT;
  41 }
  42
  43 static inline void wbt_track(struct blk_issue_stat *stat, enum wbt_flags wb_acct)
  44 {
  45         stat->time |= ((u64) wb_acct) << BLK_STAT_SHIFT;
  46 }
  47
  48 static inline bool wbt_is_tracked(struct blk_issue_stat *stat)
  49 {
  50         return (stat->time >> BLK_STAT_SHIFT) & WBT_TRACKED;
  51 }
  52
  53 static inline bool wbt_is_read(struct blk_issue_stat *stat)
  54 {
  55         return (stat->time >> BLK_STAT_SHIFT) & WBT_READ;
  56 }
  57
  58 struct rq_wait {
  59         wait_queue_head_t wait;
  60         atomic_t inflight;
  61 };
  62
  63 struct rq_wb {
  64         /*
  65          * Settings that govern how we throttle
  66          */
  67         unsigned int wb_background;             /* background writeback */
  68         unsigned int wb_normal;                 /* normal writeback */
  69         unsigned int wb_max;                    /* max throughput writeback */
  70         int scale_step;
  71         bool scaled_max;
  72
  73         short enable_state;                     /* WBT_STATE_* */
  74
  75         /*
  76          * Number of consecutive periods where we don't have enough
  77          * information to make a firm scale up/down decision.
  78          */
  79         unsigned int unknown_cnt;
  80
  81         u64 win_nsec;                           /* default window size */
  82         u64 cur_win_nsec;                       /* current window size */
  83
  84         struct timer_list window_timer;
  85
  86         s64 sync_issue;
  87         void *sync_cookie;
  88
  89         unsigned int wc;
  90         unsigned int queue_depth;
  91
  92         unsigned long last_issue;               /* last non-throttled issue */
  93         unsigned long last_comp;                /* last non-throttled comp */
  94         unsigned long min_lat_nsec;
  95         struct request_queue *queue;
  96         struct rq_wait rq_wait[WBT_NUM_RWQ];
  97 };
  98
  99 static inline unsigned int wbt_inflight(struct rq_wb *rwb)
 100 {
 101         unsigned int i, ret = 0;
 102
 103         for (i = 0; i < WBT_NUM_RWQ; i++)
 104                 ret += atomic_read(&rwb->rq_wait[i].inflight);
 105
 106         return ret;
 107 }
 108
 109 #ifdef CONFIG_BLK_WBT
 110
 111 void __wbt_done(struct rq_wb *, enum wbt_flags);
 112 void wbt_done(struct rq_wb *, struct blk_issue_stat *);
 113 enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *);
 114 int wbt_init(struct request_queue *);
 115 void wbt_exit(struct request_queue *);
 116 void wbt_update_limits(struct rq_wb *);
 117 void wbt_requeue(struct rq_wb *, struct blk_issue_stat *);
 118 void wbt_issue(struct rq_wb *, struct blk_issue_stat *);
 119 void wbt_disable_default(struct request_queue *);
 120
 121 void wbt_set_queue_depth(struct rq_wb *, unsigned int);
 122 void wbt_set_write_cache(struct rq_wb *, bool);
 123
 124 u64 wbt_default_latency_nsec(struct request_queue *);
 125
 126 #else
 127
 128 static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags)
 129 {
 130 }
 131 static inline void wbt_done(struct rq_wb *rwb, struct blk_issue_stat *stat)
 132 {
 133 }
 134 static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio,
 135                                       spinlock_t *lock)
 136 {
 137         return 0;
 138 }
 139 static inline int wbt_init(struct request_queue *q)
 140 {
 141         return -EINVAL;
 142 }
 143 static inline void wbt_exit(struct request_queue *q)
 144 {
 145 }
 146 static inline void wbt_update_limits(struct rq_wb *rwb)
 147 {
 148 }
 149 static inline void wbt_requeue(struct rq_wb *rwb, struct blk_issue_stat *stat)
 150 {
 151 }
 152 static inline void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat)
 153 {
 154 }
 155 static inline void wbt_disable_default(struct request_queue *q)
 156 {
 157 }
 158 static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
 159 {
 160 }
 161 static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc)
 162 {
 163 }
 164 static inline u64 wbt_default_latency_nsec(struct request_queue *q)
 165 {
 166         return 0;
 167 }
 168
 169 #endif /* CONFIG_BLK_WBT */
 170
 171 #endif