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git.ipfire.org Git - thirdparty/linux.git/blob - block/blk-stat.h
1 /* SPDX-License-Identifier: GPL-2.0 */
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>
12 * struct blk_stat_callback - Block statistics callback.
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.
19 struct blk_stat_callback
{
21 * @list: RCU list of callbacks for a &struct request_queue.
23 struct list_head list
;
26 * @timer: Timer for the next callback invocation.
28 struct timer_list timer
;
31 * @cpu_stat: Per-cpu statistics buckets.
33 struct blk_rq_stat __percpu
*cpu_stat
;
36 * @bucket_fn: Given a request, returns which statistics bucket it
37 * should be accounted under. Return -1 for no bucket for this
40 int (*bucket_fn
)(const struct request
*);
43 * @buckets: Number of statistics buckets.
48 * @stat: Array of statistics buckets.
50 struct blk_rq_stat
*stat
;
53 * @fn: Callback function.
55 void (*timer_fn
)(struct blk_stat_callback
*);
58 * @data: Private pointer for the user.
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
);
69 void blk_stat_add(struct request
*rq
, u64 now
);
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
);
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.
82 * See &struct blk_stat_callback for details on the callback functions.
84 * Return: &struct blk_stat_callback on success or NULL on ENOMEM.
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
);
92 * blk_stat_add_callback() - Add a block statistics callback to be run on a
94 * @q: The request queue.
97 * Note that a single &struct blk_stat_callback can only be added to a single
98 * &struct request_queue.
100 void blk_stat_add_callback(struct request_queue
*q
,
101 struct blk_stat_callback
*cb
);
104 * blk_stat_remove_callback() - Remove a block statistics callback from a
106 * @q: The request queue.
109 * When this returns, the callback is not running on any CPUs and will not be
110 * called again unless readded.
112 void blk_stat_remove_callback(struct request_queue
*q
,
113 struct blk_stat_callback
*cb
);
116 * blk_stat_free_callback() - Free a block statistics callback.
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().
124 void blk_stat_free_callback(struct blk_stat_callback
*cb
);
127 * blk_stat_is_active() - Check if a block statistics callback is currently
128 * gathering statistics.
131 static inline bool blk_stat_is_active(struct blk_stat_callback
*cb
)
133 return timer_pending(&cb
->timer
);
137 * blk_stat_activate_nsecs() - Gather block statistics during a time window in
140 * @nsecs: Number of nanoseconds to gather statistics for.
142 * The timer callback will be called when the window expires.
144 static inline void blk_stat_activate_nsecs(struct blk_stat_callback
*cb
,
147 mod_timer(&cb
->timer
, jiffies
+ nsecs_to_jiffies(nsecs
));
150 static inline void blk_stat_deactivate(struct blk_stat_callback
*cb
)
152 del_timer_sync(&cb
->timer
);
156 * blk_stat_activate_msecs() - Gather block statistics during a time window in
159 * @msecs: Number of milliseconds to gather statistics for.
161 * The timer callback will be called when the window expires.
163 static inline void blk_stat_activate_msecs(struct blk_stat_callback
*cb
,
166 mod_timer(&cb
->timer
, jiffies
+ msecs_to_jiffies(msecs
));
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
*);