1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef BLK_THROTTLE_H 3 #define BLK_THROTTLE_H 4 5 #include "blk-cgroup-rwstat.h" 6 7 /* 8 * To implement hierarchical throttling, throtl_grps form a tree and bios 9 * are dispatched upwards level by level until they reach the top and get 10 * issued. When dispatching bios from the children and local group at each 11 * level, if the bios are dispatched into a single bio_list, there's a risk 12 * of a local or child group which can queue many bios at once filling up 13 * the list starving others. 14 * 15 * To avoid such starvation, dispatched bios are queued separately 16 * according to where they came from. When they are again dispatched to 17 * the parent, they're popped in round-robin order so that no single source 18 * hogs the dispatch window. 19 * 20 * throtl_qnode is used to keep the queued bios separated by their sources. 21 * Bios are queued to throtl_qnode which in turn is queued to 22 * throtl_service_queue and then dispatched in round-robin order. 23 * 24 * It's also used to track the reference counts on blkg's. A qnode always 25 * belongs to a throtl_grp and gets queued on itself or the parent, so 26 * incrementing the reference of the associated throtl_grp when a qnode is 27 * queued and decrementing when dequeued is enough to keep the whole blkg 28 * tree pinned while bios are in flight. 29 */ 30 struct throtl_qnode { 31 struct list_head node; /* service_queue->queued[] */ 32 struct bio_list bios; /* queued bios */ 33 struct throtl_grp *tg; /* tg this qnode belongs to */ 34 }; 35 36 struct throtl_service_queue { 37 struct throtl_service_queue *parent_sq; /* the parent service_queue */ 38 39 /* 40 * Bios queued directly to this service_queue or dispatched from 41 * children throtl_grp's. 42 */ 43 struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ 44 unsigned int nr_queued[2]; /* number of queued bios */ 45 46 /* 47 * RB tree of active children throtl_grp's, which are sorted by 48 * their ->disptime. 49 */ 50 struct rb_root_cached pending_tree; /* RB tree of active tgs */ 51 unsigned int nr_pending; /* # queued in the tree */ 52 unsigned long first_pending_disptime; /* disptime of the first tg */ 53 struct timer_list pending_timer; /* fires on first_pending_disptime */ 54 }; 55 56 enum tg_state_flags { 57 THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ 58 THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ 59 THROTL_TG_CANCELING = 1 << 2, /* starts to cancel bio */ 60 }; 61 62 struct throtl_grp { 63 /* must be the first member */ 64 struct blkg_policy_data pd; 65 66 /* active throtl group service_queue member */ 67 struct rb_node rb_node; 68 69 /* throtl_data this group belongs to */ 70 struct throtl_data *td; 71 72 /* this group's service queue */ 73 struct throtl_service_queue service_queue; 74 75 /* 76 * qnode_on_self is used when bios are directly queued to this 77 * throtl_grp so that local bios compete fairly with bios 78 * dispatched from children. qnode_on_parent is used when bios are 79 * dispatched from this throtl_grp into its parent and will compete 80 * with the sibling qnode_on_parents and the parent's 81 * qnode_on_self. 82 */ 83 struct throtl_qnode qnode_on_self[2]; 84 struct throtl_qnode qnode_on_parent[2]; 85 86 /* 87 * Dispatch time in jiffies. This is the estimated time when group 88 * will unthrottle and is ready to dispatch more bio. It is used as 89 * key to sort active groups in service tree. 90 */ 91 unsigned long disptime; 92 93 unsigned int flags; 94 95 /* are there any throtl rules between this group and td? */ 96 bool has_rules_bps[2]; 97 bool has_rules_iops[2]; 98 99 /* bytes per second rate limits */ 100 uint64_t bps[2]; 101 102 /* IOPS limits */ 103 unsigned int iops[2]; 104 105 /* Number of bytes dispatched in current slice */ 106 int64_t bytes_disp[2]; 107 /* Number of bio's dispatched in current slice */ 108 int io_disp[2]; 109 110 /* 111 * The following two fields are updated when new configuration is 112 * submitted while some bios are still throttled, they record how many 113 * bytes/ios are waited already in previous configuration, and they will 114 * be used to calculate wait time under new configuration. 115 */ 116 long long carryover_bytes[2]; 117 int carryover_ios[2]; 118 119 unsigned long last_check_time; 120 121 /* When did we start a new slice */ 122 unsigned long slice_start[2]; 123 unsigned long slice_end[2]; 124 125 struct blkg_rwstat stat_bytes; 126 struct blkg_rwstat stat_ios; 127 }; 128 129 extern struct blkcg_policy blkcg_policy_throtl; 130 131 static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) 132 { 133 return pd ? container_of(pd, struct throtl_grp, pd) : NULL; 134 } 135 136 static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) 137 { 138 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); 139 } 140 141 /* 142 * Internal throttling interface 143 */ 144 #ifndef CONFIG_BLK_DEV_THROTTLING 145 static inline void blk_throtl_exit(struct gendisk *disk) { } 146 static inline bool blk_throtl_bio(struct bio *bio) { return false; } 147 static inline void blk_throtl_cancel_bios(struct gendisk *disk) { } 148 #else /* CONFIG_BLK_DEV_THROTTLING */ 149 void blk_throtl_exit(struct gendisk *disk); 150 bool __blk_throtl_bio(struct bio *bio); 151 void blk_throtl_cancel_bios(struct gendisk *disk); 152 153 static inline bool blk_throtl_activated(struct request_queue *q) 154 { 155 return q->td != NULL; 156 } 157 158 static inline bool blk_should_throtl(struct bio *bio) 159 { 160 struct throtl_grp *tg; 161 int rw = bio_data_dir(bio); 162 163 /* 164 * This is called under bio_queue_enter(), and it's synchronized with 165 * the activation of blk-throtl, which is protected by 166 * blk_mq_freeze_queue(). 167 */ 168 if (!blk_throtl_activated(bio->bi_bdev->bd_queue)) 169 return false; 170 171 tg = blkg_to_tg(bio->bi_blkg); 172 if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) { 173 if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { 174 bio_set_flag(bio, BIO_CGROUP_ACCT); 175 blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf, 176 bio->bi_iter.bi_size); 177 } 178 blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1); 179 } 180 181 /* iops limit is always counted */ 182 if (tg->has_rules_iops[rw]) 183 return true; 184 185 if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED)) 186 return true; 187 188 return false; 189 } 190 191 static inline bool blk_throtl_bio(struct bio *bio) 192 { 193 194 if (!blk_should_throtl(bio)) 195 return false; 196 197 return __blk_throtl_bio(bio); 198 } 199 #endif /* CONFIG_BLK_DEV_THROTTLING */ 200 201 #endif 202