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