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cf43e6be JA |
1 | #ifndef BLK_STAT_H |
2 | #define BLK_STAT_H | |
3 | ||
34dbad5d OS |
4 | #include <linux/kernel.h> |
5 | #include <linux/blkdev.h> | |
6 | #include <linux/ktime.h> | |
7 | #include <linux/rcupdate.h> | |
8 | #include <linux/timer.h> | |
cf43e6be JA |
9 | |
10 | /* | |
11 | * Upper 3 bits can be used elsewhere | |
12 | */ | |
13 | #define BLK_STAT_RES_BITS 3 | |
14 | #define BLK_STAT_SHIFT (64 - BLK_STAT_RES_BITS) | |
15 | #define BLK_STAT_TIME_MASK ((1ULL << BLK_STAT_SHIFT) - 1) | |
16 | #define BLK_STAT_MASK ~BLK_STAT_TIME_MASK | |
17 | ||
34dbad5d OS |
18 | /** |
19 | * struct blk_stat_callback - Block statistics callback. | |
20 | * | |
21 | * A &struct blk_stat_callback is associated with a &struct request_queue. While | |
22 | * @timer is active, that queue's request completion latencies are sorted into | |
23 | * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the | |
24 | * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked. | |
25 | */ | |
26 | struct blk_stat_callback { | |
27 | /* | |
28 | * @list: RCU list of callbacks for a &struct request_queue. | |
29 | */ | |
30 | struct list_head list; | |
31 | ||
32 | /** | |
33 | * @timer: Timer for the next callback invocation. | |
34 | */ | |
35 | struct timer_list timer; | |
36 | ||
37 | /** | |
38 | * @cpu_stat: Per-cpu statistics buckets. | |
39 | */ | |
40 | struct blk_rq_stat __percpu *cpu_stat; | |
41 | ||
42 | /** | |
43 | * @bucket_fn: Given a request, returns which statistics bucket it | |
44 | * should be accounted under. | |
45 | */ | |
46 | unsigned int (*bucket_fn)(const struct request *); | |
47 | ||
48 | /** | |
49 | * @buckets: Number of statistics buckets. | |
50 | */ | |
51 | unsigned int buckets; | |
52 | ||
53 | /** | |
54 | * @stat: Array of statistics buckets. | |
55 | */ | |
56 | struct blk_rq_stat *stat; | |
57 | ||
58 | /** | |
59 | * @fn: Callback function. | |
60 | */ | |
61 | void (*timer_fn)(struct blk_stat_callback *); | |
62 | ||
63 | /** | |
64 | * @data: Private pointer for the user. | |
65 | */ | |
66 | void *data; | |
67 | ||
68 | struct rcu_head rcu; | |
69 | }; | |
70 | ||
71 | struct blk_queue_stats *blk_alloc_queue_stats(void); | |
72 | void blk_free_queue_stats(struct blk_queue_stats *); | |
73 | ||
74 | void blk_stat_add(struct request *); | |
75 | ||
76 | static inline void blk_stat_set_issue_time(struct blk_issue_stat *stat) | |
77 | { | |
78 | stat->time = ((stat->time & BLK_STAT_MASK) | | |
79 | (ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK)); | |
80 | } | |
cf43e6be JA |
81 | |
82 | static inline u64 __blk_stat_time(u64 time) | |
83 | { | |
84 | return time & BLK_STAT_TIME_MASK; | |
85 | } | |
86 | ||
87 | static inline u64 blk_stat_time(struct blk_issue_stat *stat) | |
88 | { | |
89 | return __blk_stat_time(stat->time); | |
90 | } | |
91 | ||
34dbad5d OS |
92 | /* |
93 | * blk_stat_rq_ddir() - Bucket callback function for the request data direction. | |
94 | * @rq: Request. | |
95 | * | |
96 | * This is the same as rq_data_dir() but as a function so it can be used as | |
97 | * @bucket_fn for blk_stat_alloc_callback(). | |
98 | * | |
99 | * Return: Data direction of the request, either READ or WRITE. | |
100 | */ | |
101 | unsigned int blk_stat_rq_ddir(const struct request *rq); | |
102 | ||
103 | /** | |
104 | * blk_stat_alloc_callback() - Allocate a block statistics callback. | |
105 | * @timer_fn: Timer callback function. | |
106 | * @bucket_fn: Bucket callback function. | |
107 | * @buckets: Number of statistics buckets. | |
108 | * @data: Value for the @data field of the &struct blk_stat_callback. | |
109 | * | |
110 | * See &struct blk_stat_callback for details on the callback functions. | |
111 | * | |
112 | * Return: &struct blk_stat_callback on success or NULL on ENOMEM. | |
113 | */ | |
114 | struct blk_stat_callback * | |
115 | blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), | |
116 | unsigned int (*bucket_fn)(const struct request *), | |
117 | unsigned int buckets, void *data); | |
118 | ||
119 | /** | |
120 | * blk_stat_add_callback() - Add a block statistics callback to be run on a | |
121 | * request queue. | |
122 | * @q: The request queue. | |
123 | * @cb: The callback. | |
124 | * | |
125 | * Note that a single &struct blk_stat_callback can only be added to a single | |
126 | * &struct request_queue. | |
127 | */ | |
128 | void blk_stat_add_callback(struct request_queue *q, | |
129 | struct blk_stat_callback *cb); | |
130 | ||
131 | /** | |
132 | * blk_stat_remove_callback() - Remove a block statistics callback from a | |
133 | * request queue. | |
134 | * @q: The request queue. | |
135 | * @cb: The callback. | |
136 | * | |
137 | * When this returns, the callback is not running on any CPUs and will not be | |
138 | * called again unless readded. | |
139 | */ | |
140 | void blk_stat_remove_callback(struct request_queue *q, | |
141 | struct blk_stat_callback *cb); | |
142 | ||
143 | /** | |
144 | * blk_stat_free_callback() - Free a block statistics callback. | |
145 | * @cb: The callback. | |
146 | * | |
147 | * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must | |
148 | * not be associated with a request queue. I.e., if it was previously added with | |
149 | * blk_stat_add_callback(), it must also have been removed since then with | |
150 | * blk_stat_remove_callback(). | |
151 | */ | |
152 | void blk_stat_free_callback(struct blk_stat_callback *cb); | |
153 | ||
154 | /** | |
155 | * blk_stat_is_active() - Check if a block statistics callback is currently | |
156 | * gathering statistics. | |
157 | * @cb: The callback. | |
158 | */ | |
159 | static inline bool blk_stat_is_active(struct blk_stat_callback *cb) | |
160 | { | |
161 | return timer_pending(&cb->timer); | |
162 | } | |
163 | ||
164 | /** | |
165 | * blk_stat_activate_nsecs() - Gather block statistics during a time window in | |
166 | * nanoseconds. | |
167 | * @cb: The callback. | |
168 | * @nsecs: Number of nanoseconds to gather statistics for. | |
169 | * | |
170 | * The timer callback will be called when the window expires. | |
171 | */ | |
172 | static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb, | |
173 | u64 nsecs) | |
174 | { | |
175 | mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs)); | |
176 | } | |
177 | ||
178 | /** | |
179 | * blk_stat_activate_msecs() - Gather block statistics during a time window in | |
180 | * milliseconds. | |
181 | * @cb: The callback. | |
182 | * @msecs: Number of milliseconds to gather statistics for. | |
183 | * | |
184 | * The timer callback will be called when the window expires. | |
185 | */ | |
186 | static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb, | |
187 | unsigned int msecs) | |
188 | { | |
189 | mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs)); | |
190 | } | |
191 | ||
cf43e6be | 192 | #endif |