Line data    Source code

       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             : bool blk_stats_alloc_enable(struct request_queue *q);
      68             : 
      69             : void blk_stat_add(struct request *rq, u64 now);
      70             : 
      71             : /* record time/size info in request but not add a callback */
      72             : void blk_stat_enable_accounting(struct request_queue *q);
      73             : void blk_stat_disable_accounting(struct request_queue *q);
      74             : 
      75             : /**
      76             :  * blk_stat_alloc_callback() - Allocate a block statistics callback.
      77             :  * @timer_fn: Timer callback function.
      78             :  * @bucket_fn: Bucket callback function.
      79             :  * @buckets: Number of statistics buckets.
      80             :  * @data: Value for the @data field of the &struct blk_stat_callback.
      81             :  *
      82             :  * See &struct blk_stat_callback for details on the callback functions.
      83             :  *
      84             :  * Return: &struct blk_stat_callback on success or NULL on ENOMEM.
      85             :  */
      86             : struct blk_stat_callback *
      87             : blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
      88             :                         int (*bucket_fn)(const struct request *),
      89             :                         unsigned int buckets, void *data);
      90             : 
      91             : /**
      92             :  * blk_stat_add_callback() - Add a block statistics callback to be run on a
      93             :  * request queue.
      94             :  * @q: The request queue.
      95             :  * @cb: The callback.
      96             :  *
      97             :  * Note that a single &struct blk_stat_callback can only be added to a single
      98             :  * &struct request_queue.
      99             :  */
     100             : void blk_stat_add_callback(struct request_queue *q,
     101             :                            struct blk_stat_callback *cb);
     102             : 
     103             : /**
     104             :  * blk_stat_remove_callback() - Remove a block statistics callback from a
     105             :  * request queue.
     106             :  * @q: The request queue.
     107             :  * @cb: The callback.
     108             :  *
     109             :  * When this returns, the callback is not running on any CPUs and will not be
     110             :  * called again unless readded.
     111             :  */
     112             : void blk_stat_remove_callback(struct request_queue *q,
     113             :                               struct blk_stat_callback *cb);
     114             : 
     115             : /**
     116             :  * blk_stat_free_callback() - Free a block statistics callback.
     117             :  * @cb: The callback.
     118             :  *
     119             :  * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must
     120             :  * not be associated with a request queue. I.e., if it was previously added with
     121             :  * blk_stat_add_callback(), it must also have been removed since then with
     122             :  * blk_stat_remove_callback().
     123             :  */
     124             : void blk_stat_free_callback(struct blk_stat_callback *cb);
     125             : 
     126             : /**
     127             :  * blk_stat_is_active() - Check if a block statistics callback is currently
     128             :  * gathering statistics.
     129             :  * @cb: The callback.
     130             :  */
     131             : static inline bool blk_stat_is_active(struct blk_stat_callback *cb)
     132             : {
     133           0 :         return timer_pending(&cb->timer);
     134             : }
     135             : 
     136             : /**
     137             :  * blk_stat_activate_nsecs() - Gather block statistics during a time window in
     138             :  * nanoseconds.
     139             :  * @cb: The callback.
     140             :  * @nsecs: Number of nanoseconds to gather statistics for.
     141             :  *
     142             :  * The timer callback will be called when the window expires.
     143             :  */
     144             : static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb,
     145             :                                            u64 nsecs)
     146             : {
     147             :         mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs));
     148             : }
     149             : 
     150             : static inline void blk_stat_deactivate(struct blk_stat_callback *cb)
     151             : {
     152             :         del_timer_sync(&cb->timer);
     153             : }
     154             : 
     155             : /**
     156             :  * blk_stat_activate_msecs() - Gather block statistics during a time window in
     157             :  * milliseconds.
     158             :  * @cb: The callback.
     159             :  * @msecs: Number of milliseconds to gather statistics for.
     160             :  *
     161             :  * The timer callback will be called when the window expires.
     162             :  */
     163             : static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb,
     164             :                                            unsigned int msecs)
     165             : {
     166             :         mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs));
     167             : }
     168             : 
     169             : void blk_rq_stat_add(struct blk_rq_stat *, u64);
     170             : void blk_rq_stat_sum(struct blk_rq_stat *, struct blk_rq_stat *);
     171             : void blk_rq_stat_init(struct blk_rq_stat *);
     172             : 
     173             : #endif