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1#ifndef BLK_THROTTLE_H
2#define BLK_THROTTLE_H
3
4#include "blk-cgroup-rwstat.h"
5
6/*
7 * To implement hierarchical throttling, throtl_grps form a tree and bios
8 * are dispatched upwards level by level until they reach the top and get
9 * issued. When dispatching bios from the children and local group at each
10 * level, if the bios are dispatched into a single bio_list, there's a risk
11 * of a local or child group which can queue many bios at once filling up
12 * the list starving others.
13 *
14 * To avoid such starvation, dispatched bios are queued separately
15 * according to where they came from. When they are again dispatched to
16 * the parent, they're popped in round-robin order so that no single source
17 * hogs the dispatch window.
18 *
19 * throtl_qnode is used to keep the queued bios separated by their sources.
20 * Bios are queued to throtl_qnode which in turn is queued to
21 * throtl_service_queue and then dispatched in round-robin order.
22 *
23 * It's also used to track the reference counts on blkg's. A qnode always
24 * belongs to a throtl_grp and gets queued on itself or the parent, so
25 * incrementing the reference of the associated throtl_grp when a qnode is
26 * queued and decrementing when dequeued is enough to keep the whole blkg
27 * tree pinned while bios are in flight.
28 */
29struct throtl_qnode {
30 struct list_head node; /* service_queue->queued[] */
31 struct bio_list bios; /* queued bios */
32 struct throtl_grp *tg; /* tg this qnode belongs to */
33};
34
35struct throtl_service_queue {
36 struct throtl_service_queue *parent_sq; /* the parent service_queue */
37
38 /*
39 * Bios queued directly to this service_queue or dispatched from
40 * children throtl_grp's.
41 */
42 struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */
43 unsigned int nr_queued[2]; /* number of queued bios */
44
45 /*
46 * RB tree of active children throtl_grp's, which are sorted by
47 * their ->disptime.
48 */
49 struct rb_root_cached pending_tree; /* RB tree of active tgs */
50 unsigned int nr_pending; /* # queued in the tree */
51 unsigned long first_pending_disptime; /* disptime of the first tg */
52 struct timer_list pending_timer; /* fires on first_pending_disptime */
53};
54
55enum tg_state_flags {
56 THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
57 THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */
58 THROTL_TG_CANCELING = 1 << 2, /* starts to cancel bio */
59};
60
61enum {
62 LIMIT_LOW,
63 LIMIT_MAX,
64 LIMIT_CNT,
65};
66
67struct throtl_grp {
68 /* must be the first member */
69 struct blkg_policy_data pd;
70
71 /* active throtl group service_queue member */
72 struct rb_node rb_node;
73
74 /* throtl_data this group belongs to */
75 struct throtl_data *td;
76
77 /* this group's service queue */
78 struct throtl_service_queue service_queue;
79
80 /*
81 * qnode_on_self is used when bios are directly queued to this
82 * throtl_grp so that local bios compete fairly with bios
83 * dispatched from children. qnode_on_parent is used when bios are
84 * dispatched from this throtl_grp into its parent and will compete
85 * with the sibling qnode_on_parents and the parent's
86 * qnode_on_self.
87 */
88 struct throtl_qnode qnode_on_self[2];
89 struct throtl_qnode qnode_on_parent[2];
90
91 /*
92 * Dispatch time in jiffies. This is the estimated time when group
93 * will unthrottle and is ready to dispatch more bio. It is used as
94 * key to sort active groups in service tree.
95 */
96 unsigned long disptime;
97
98 unsigned int flags;
99
100 /* are there any throtl rules between this group and td? */
101 bool has_rules_bps[2];
102 bool has_rules_iops[2];
103
104 /* internally used bytes per second rate limits */
105 uint64_t bps[2][LIMIT_CNT];
106 /* user configured bps limits */
107 uint64_t bps_conf[2][LIMIT_CNT];
108
109 /* internally used IOPS limits */
110 unsigned int iops[2][LIMIT_CNT];
111 /* user configured IOPS limits */
112 unsigned int iops_conf[2][LIMIT_CNT];
113
114 /* Number of bytes dispatched in current slice */
115 uint64_t bytes_disp[2];
116 /* Number of bio's dispatched in current slice */
117 unsigned int io_disp[2];
118
119 unsigned long last_low_overflow_time[2];
120
121 uint64_t last_bytes_disp[2];
122 unsigned int last_io_disp[2];
123
124 /*
125 * The following two fields are updated when new configuration is
126 * submitted while some bios are still throttled, they record how many
127 * bytes/ios are waited already in previous configuration, and they will
128 * be used to calculate wait time under new configuration.
129 */
130 long long carryover_bytes[2];
131 int carryover_ios[2];
132
133 unsigned long last_check_time;
134
135 unsigned long latency_target; /* us */
136 unsigned long latency_target_conf; /* us */
137 /* When did we start a new slice */
138 unsigned long slice_start[2];
139 unsigned long slice_end[2];
140
141 unsigned long last_finish_time; /* ns / 1024 */
142 unsigned long checked_last_finish_time; /* ns / 1024 */
143 unsigned long avg_idletime; /* ns / 1024 */
144 unsigned long idletime_threshold; /* us */
145 unsigned long idletime_threshold_conf; /* us */
146
147 unsigned int bio_cnt; /* total bios */
148 unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
149 unsigned long bio_cnt_reset_time;
150
151 struct blkg_rwstat stat_bytes;
152 struct blkg_rwstat stat_ios;
153};
154
155extern struct blkcg_policy blkcg_policy_throtl;
156
157static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
158{
159 return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
160}
161
162static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
163{
164 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
165}
166
167/*
168 * Internal throttling interface
169 */
170#ifndef CONFIG_BLK_DEV_THROTTLING
171static inline int blk_throtl_init(struct gendisk *disk) { return 0; }
172static inline void blk_throtl_exit(struct gendisk *disk) { }
173static inline void blk_throtl_register(struct gendisk *disk) { }
174static inline bool blk_throtl_bio(struct bio *bio) { return false; }
175static inline void blk_throtl_cancel_bios(struct gendisk *disk) { }
176#else /* CONFIG_BLK_DEV_THROTTLING */
177int blk_throtl_init(struct gendisk *disk);
178void blk_throtl_exit(struct gendisk *disk);
179void blk_throtl_register(struct gendisk *disk);
180bool __blk_throtl_bio(struct bio *bio);
181void blk_throtl_cancel_bios(struct gendisk *disk);
182
183static inline bool blk_should_throtl(struct bio *bio)
184{
185 struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);
186 int rw = bio_data_dir(bio);
187
188 if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
189 if (!bio_flagged(bio, BIO_CGROUP_ACCT)) {
190 bio_set_flag(bio, BIO_CGROUP_ACCT);
191 blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
192 bio->bi_iter.bi_size);
193 }
194 blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
195 }
196
197 /* iops limit is always counted */
198 if (tg->has_rules_iops[rw])
199 return true;
200
201 if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED))
202 return true;
203
204 return false;
205}
206
207static inline bool blk_throtl_bio(struct bio *bio)
208{
209
210 if (!blk_should_throtl(bio))
211 return false;
212
213 return __blk_throtl_bio(bio);
214}
215#endif /* CONFIG_BLK_DEV_THROTTLING */
216
217#endif