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 | return timer_pending(timer: &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(timer: &cb->timer, expires: jiffies + nsecs_to_jiffies(n: nsecs)); |
148 | } |
149 | |
150 | static inline void blk_stat_deactivate(struct blk_stat_callback *cb) |
151 | { |
152 | del_timer_sync(timer: &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(timer: &cb->timer, expires: jiffies + msecs_to_jiffies(m: 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 |
174 | |