xref: /openbmc/linux/block/blk-wbt.h (revision aac5987a) 
1 #ifndef WB_THROTTLE_H
2 #define WB_THROTTLE_H
3 
4 #include <linux/kernel.h>
5 #include <linux/atomic.h>
6 #include <linux/wait.h>
7 #include <linux/timer.h>
8 #include <linux/ktime.h>
9 
10 #include "blk-stat.h"
11 
12 enum wbt_flags {
13 	WBT_TRACKED		= 1,	/* write, tracked for throttling */
14 	WBT_READ		= 2,	/* read */
15 	WBT_KSWAPD		= 4,	/* write, from kswapd */
16 
17 	WBT_NR_BITS		= 3,	/* number of bits */
18 };
19 
20 enum {
21 	WBT_NUM_RWQ		= 2,
22 };
23 
24 /*
25  * Enable states. Either off, or on by default (done at init time),
26  * or on through manual setup in sysfs.
27  */
28 enum {
29 	WBT_STATE_ON_DEFAULT	= 1,
30 	WBT_STATE_ON_MANUAL	= 2,
31 };
32 
33 static inline void wbt_clear_state(struct blk_issue_stat *stat)
34 {
35 	stat->time &= BLK_STAT_TIME_MASK;
36 }
37 
38 static inline enum wbt_flags wbt_stat_to_mask(struct blk_issue_stat *stat)
39 {
40 	return (stat->time & BLK_STAT_MASK) >> BLK_STAT_SHIFT;
41 }
42 
43 static inline void wbt_track(struct blk_issue_stat *stat, enum wbt_flags wb_acct)
44 {
45 	stat->time |= ((u64) wb_acct) << BLK_STAT_SHIFT;
46 }
47 
48 static inline bool wbt_is_tracked(struct blk_issue_stat *stat)
49 {
50 	return (stat->time >> BLK_STAT_SHIFT) & WBT_TRACKED;
51 }
52 
53 static inline bool wbt_is_read(struct blk_issue_stat *stat)
54 {
55 	return (stat->time >> BLK_STAT_SHIFT) & WBT_READ;
56 }
57 
58 struct rq_wait {
59 	wait_queue_head_t wait;
60 	atomic_t inflight;
61 };
62 
63 struct rq_wb {
64 	/*
65 	 * Settings that govern how we throttle
66 	 */
67 	unsigned int wb_background;		/* background writeback */
68 	unsigned int wb_normal;			/* normal writeback */
69 	unsigned int wb_max;			/* max throughput writeback */
70 	int scale_step;
71 	bool scaled_max;
72 
73 	short enable_state;			/* WBT_STATE_* */
74 
75 	/*
76 	 * Number of consecutive periods where we don't have enough
77 	 * information to make a firm scale up/down decision.
78 	 */
79 	unsigned int unknown_cnt;
80 
81 	u64 win_nsec;				/* default window size */
82 	u64 cur_win_nsec;			/* current window size */
83 
84 	struct timer_list window_timer;
85 
86 	s64 sync_issue;
87 	void *sync_cookie;
88 
89 	unsigned int wc;
90 	unsigned int queue_depth;
91 
92 	unsigned long last_issue;		/* last non-throttled issue */
93 	unsigned long last_comp;		/* last non-throttled comp */
94 	unsigned long min_lat_nsec;
95 	struct request_queue *queue;
96 	struct rq_wait rq_wait[WBT_NUM_RWQ];
97 };
98 
99 static inline unsigned int wbt_inflight(struct rq_wb *rwb)
100 {
101 	unsigned int i, ret = 0;
102 
103 	for (i = 0; i < WBT_NUM_RWQ; i++)
104 		ret += atomic_read(&rwb->rq_wait[i].inflight);
105 
106 	return ret;
107 }
108 
109 #ifdef CONFIG_BLK_WBT
110 
111 void __wbt_done(struct rq_wb *, enum wbt_flags);
112 void wbt_done(struct rq_wb *, struct blk_issue_stat *);
113 enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *);
114 int wbt_init(struct request_queue *);
115 void wbt_exit(struct request_queue *);
116 void wbt_update_limits(struct rq_wb *);
117 void wbt_requeue(struct rq_wb *, struct blk_issue_stat *);
118 void wbt_issue(struct rq_wb *, struct blk_issue_stat *);
119 void wbt_disable_default(struct request_queue *);
120 
121 void wbt_set_queue_depth(struct rq_wb *, unsigned int);
122 void wbt_set_write_cache(struct rq_wb *, bool);
123 
124 u64 wbt_default_latency_nsec(struct request_queue *);
125 
126 #else
127 
128 static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags)
129 {
130 }
131 static inline void wbt_done(struct rq_wb *rwb, struct blk_issue_stat *stat)
132 {
133 }
134 static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio,
135 				      spinlock_t *lock)
136 {
137 	return 0;
138 }
139 static inline int wbt_init(struct request_queue *q)
140 {
141 	return -EINVAL;
142 }
143 static inline void wbt_exit(struct request_queue *q)
144 {
145 }
146 static inline void wbt_update_limits(struct rq_wb *rwb)
147 {
148 }
149 static inline void wbt_requeue(struct rq_wb *rwb, struct blk_issue_stat *stat)
150 {
151 }
152 static inline void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat)
153 {
154 }
155 static inline void wbt_disable_default(struct request_queue *q)
156 {
157 }
158 static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
159 {
160 }
161 static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc)
162 {
163 }
164 static inline u64 wbt_default_latency_nsec(struct request_queue *q)
165 {
166 	return 0;
167 }
168 
169 #endif /* CONFIG_BLK_WBT */
170 
171 #endif
172