1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef BLK_STAT_H 3 #define BLK_STAT_H 4 5 #include <linux/kernel.h> 6 #include <linux/blkdev.h> 7 #include <linux/ktime.h> 8 #include <linux/rcupdate.h> 9 #include <linux/timer.h> 10 11 /** 12 * struct blk_stat_callback - Block statistics callback. 13 * 14 * A &struct blk_stat_callback is associated with a &struct request_queue. While 15 * @timer is active, that queue's request completion latencies are sorted into 16 * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the 17 * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked. 18 */ 19 struct blk_stat_callback { 20 /* 21 * @list: RCU list of callbacks for a &struct request_queue. 22 */ 23 struct list_head list; 24 25 /** 26 * @timer: Timer for the next callback invocation. 27 */ 28 struct timer_list timer; 29 30 /** 31 * @cpu_stat: Per-cpu statistics buckets. 32 */ 33 struct blk_rq_stat __percpu *cpu_stat; 34 35 /** 36 * @bucket_fn: Given a request, returns which statistics bucket it 37 * should be accounted under. Return -1 for no bucket for this 38 * request. 39 */ 40 int (*bucket_fn)(const struct request *); 41 42 /** 43 * @buckets: Number of statistics buckets. 44 */ 45 unsigned int buckets; 46 47 /** 48 * @stat: Array of statistics buckets. 49 */ 50 struct blk_rq_stat *stat; 51 52 /** 53 * @fn: Callback function. 54 */ 55 void (*timer_fn)(struct blk_stat_callback *); 56 57 /** 58 * @data: Private pointer for the user. 59 */ 60 void *data; 61 62 struct rcu_head rcu; 63 }; 64 65 struct blk_queue_stats *blk_alloc_queue_stats(void); 66 void blk_free_queue_stats(struct blk_queue_stats *); 67 68 void blk_stat_add(struct request *rq, u64 now); 69 70 /* record time/size info in request but not add a callback */ 71 void blk_stat_enable_accounting(struct request_queue *q); 72 void blk_stat_disable_accounting(struct request_queue *q); 73 74 /** 75 * blk_stat_alloc_callback() - Allocate a block statistics callback. 76 * @timer_fn: Timer callback function. 77 * @bucket_fn: Bucket callback function. 78 * @buckets: Number of statistics buckets. 79 * @data: Value for the @data field of the &struct blk_stat_callback. 80 * 81 * See &struct blk_stat_callback for details on the callback functions. 82 * 83 * Return: &struct blk_stat_callback on success or NULL on ENOMEM. 84 */ 85 struct blk_stat_callback * 86 blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), 87 int (*bucket_fn)(const struct request *), 88 unsigned int buckets, void *data); 89 90 /** 91 * blk_stat_add_callback() - Add a block statistics callback to be run on a 92 * request queue. 93 * @q: The request queue. 94 * @cb: The callback. 95 * 96 * Note that a single &struct blk_stat_callback can only be added to a single 97 * &struct request_queue. 98 */ 99 void blk_stat_add_callback(struct request_queue *q, 100 struct blk_stat_callback *cb); 101 102 /** 103 * blk_stat_remove_callback() - Remove a block statistics callback from a 104 * request queue. 105 * @q: The request queue. 106 * @cb: The callback. 107 * 108 * When this returns, the callback is not running on any CPUs and will not be 109 * called again unless readded. 110 */ 111 void blk_stat_remove_callback(struct request_queue *q, 112 struct blk_stat_callback *cb); 113 114 /** 115 * blk_stat_free_callback() - Free a block statistics callback. 116 * @cb: The callback. 117 * 118 * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must 119 * not be associated with a request queue. I.e., if it was previously added with 120 * blk_stat_add_callback(), it must also have been removed since then with 121 * blk_stat_remove_callback(). 122 */ 123 void blk_stat_free_callback(struct blk_stat_callback *cb); 124 125 /** 126 * blk_stat_is_active() - Check if a block statistics callback is currently 127 * gathering statistics. 128 * @cb: The callback. 129 */ 130 static inline bool blk_stat_is_active(struct blk_stat_callback *cb) 131 { 132 return timer_pending(&cb->timer); 133 } 134 135 /** 136 * blk_stat_activate_nsecs() - Gather block statistics during a time window in 137 * nanoseconds. 138 * @cb: The callback. 139 * @nsecs: Number of nanoseconds to gather statistics for. 140 * 141 * The timer callback will be called when the window expires. 142 */ 143 static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb, 144 u64 nsecs) 145 { 146 mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs)); 147 } 148 149 static inline void blk_stat_deactivate(struct blk_stat_callback *cb) 150 { 151 del_timer_sync(&cb->timer); 152 } 153 154 /** 155 * blk_stat_activate_msecs() - Gather block statistics during a time window in 156 * milliseconds. 157 * @cb: The callback. 158 * @msecs: Number of milliseconds to gather statistics for. 159 * 160 * The timer callback will be called when the window expires. 161 */ 162 static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb, 163 unsigned int msecs) 164 { 165 mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs)); 166 } 167 168 void blk_rq_stat_add(struct blk_rq_stat *, u64); 169 void blk_rq_stat_sum(struct blk_rq_stat *, struct blk_rq_stat *); 170 void blk_rq_stat_init(struct blk_rq_stat *); 171 172 #endif 173