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 */ 29 struct 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 35 struct 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 55 enum 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 61 struct throtl_grp { 62 /* must be the first member */ 63 struct blkg_policy_data pd; 64 65 /* active throtl group service_queue member */ 66 struct rb_node rb_node; 67 68 /* throtl_data this group belongs to */ 69 struct throtl_data *td; 70 71 /* this group's service queue */ 72 struct throtl_service_queue service_queue; 73 74 /* 75 * qnode_on_self is used when bios are directly queued to this 76 * throtl_grp so that local bios compete fairly with bios 77 * dispatched from children. qnode_on_parent is used when bios are 78 * dispatched from this throtl_grp into its parent and will compete 79 * with the sibling qnode_on_parents and the parent's 80 * qnode_on_self. 81 */ 82 struct throtl_qnode qnode_on_self[2]; 83 struct throtl_qnode qnode_on_parent[2]; 84 85 /* 86 * Dispatch time in jiffies. This is the estimated time when group 87 * will unthrottle and is ready to dispatch more bio. It is used as 88 * key to sort active groups in service tree. 89 */ 90 unsigned long disptime; 91 92 unsigned int flags; 93 94 /* are there any throtl rules between this group and td? */ 95 bool has_rules_bps[2]; 96 bool has_rules_iops[2]; 97 98 /* bytes per second rate limits */ 99 uint64_t bps[2]; 100 101 /* IOPS limits */ 102 unsigned int iops[2]; 103 104 /* Number of bytes dispatched in current slice */ 105 uint64_t bytes_disp[2]; 106 /* Number of bio's dispatched in current slice */ 107 unsigned int io_disp[2]; 108 109 unsigned long last_low_overflow_time[2]; 110 111 uint64_t last_bytes_disp[2]; 112 unsigned int last_io_disp[2]; 113 114 /* 115 * The following two fields are updated when new configuration is 116 * submitted while some bios are still throttled, they record how many 117 * bytes/ios are waited already in previous configuration, and they will 118 * be used to calculate wait time under new configuration. 119 */ 120 long long carryover_bytes[2]; 121 int carryover_ios[2]; 122 123 unsigned long last_check_time; 124 125 /* When did we start a new slice */ 126 unsigned long slice_start[2]; 127 unsigned long slice_end[2]; 128 129 struct blkg_rwstat stat_bytes; 130 struct blkg_rwstat stat_ios; 131 }; 132 133 extern struct blkcg_policy blkcg_policy_throtl; 134 135 static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) 136 { 137 return pd ? container_of(pd, struct throtl_grp, pd) : NULL; 138 } 139 140 static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) 141 { 142 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); 143 } 144 145 /* 146 * Internal throttling interface 147 */ 148 #ifndef CONFIG_BLK_DEV_THROTTLING 149 static inline void blk_throtl_exit(struct gendisk *disk) { } 150 static inline bool blk_throtl_bio(struct bio *bio) { return false; } 151 static inline void blk_throtl_cancel_bios(struct gendisk *disk) { } 152 #else /* CONFIG_BLK_DEV_THROTTLING */ 153 void blk_throtl_exit(struct gendisk *disk); 154 bool __blk_throtl_bio(struct bio *bio); 155 void blk_throtl_cancel_bios(struct gendisk *disk); 156 157 static inline bool blk_throtl_activated(struct request_queue *q) 158 { 159 return q->td != NULL; 160 } 161 162 static inline bool blk_should_throtl(struct bio *bio) 163 { 164 struct throtl_grp *tg; 165 int rw = bio_data_dir(bio); 166 167 /* 168 * This is called under bio_queue_enter(), and it's synchronized with 169 * the activation of blk-throtl, which is protected by 170 * blk_mq_freeze_queue(). 171 */ 172 if (!blk_throtl_activated(bio->bi_bdev->bd_queue)) 173 return false; 174 175 tg = blkg_to_tg(bio->bi_blkg); 176 if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) { 177 if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { 178 bio_set_flag(bio, BIO_CGROUP_ACCT); 179 blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf, 180 bio->bi_iter.bi_size); 181 } 182 blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1); 183 } 184 185 /* iops limit is always counted */ 186 if (tg->has_rules_iops[rw]) 187 return true; 188 189 if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED)) 190 return true; 191 192 return false; 193 } 194 195 static inline bool blk_throtl_bio(struct bio *bio) 196 { 197 198 if (!blk_should_throtl(bio)) 199 return false; 200 201 return __blk_throtl_bio(bio); 202 } 203 #endif /* CONFIG_BLK_DEV_THROTTLING */ 204 205 #endif 206