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 { 56 LIMIT_LOW, 57 LIMIT_MAX, 58 LIMIT_CNT, 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[2]; 96 97 /* internally used bytes per second rate limits */ 98 uint64_t bps[2][LIMIT_CNT]; 99 /* user configured bps limits */ 100 uint64_t bps_conf[2][LIMIT_CNT]; 101 102 /* internally used IOPS limits */ 103 unsigned int iops[2][LIMIT_CNT]; 104 /* user configured IOPS limits */ 105 unsigned int iops_conf[2][LIMIT_CNT]; 106 107 /* Number of bytes dispatched in current slice */ 108 uint64_t bytes_disp[2]; 109 /* Number of bio's dispatched in current slice */ 110 unsigned int io_disp[2]; 111 112 unsigned long last_low_overflow_time[2]; 113 114 uint64_t last_bytes_disp[2]; 115 unsigned int last_io_disp[2]; 116 117 unsigned long last_check_time; 118 119 unsigned long latency_target; /* us */ 120 unsigned long latency_target_conf; /* us */ 121 /* When did we start a new slice */ 122 unsigned long slice_start[2]; 123 unsigned long slice_end[2]; 124 125 unsigned long last_finish_time; /* ns / 1024 */ 126 unsigned long checked_last_finish_time; /* ns / 1024 */ 127 unsigned long avg_idletime; /* ns / 1024 */ 128 unsigned long idletime_threshold; /* us */ 129 unsigned long idletime_threshold_conf; /* us */ 130 131 unsigned int bio_cnt; /* total bios */ 132 unsigned int bad_bio_cnt; /* bios exceeding latency threshold */ 133 unsigned long bio_cnt_reset_time; 134 135 atomic_t io_split_cnt[2]; 136 atomic_t last_io_split_cnt[2]; 137 138 struct blkg_rwstat stat_bytes; 139 struct blkg_rwstat stat_ios; 140 }; 141 142 extern struct blkcg_policy blkcg_policy_throtl; 143 144 static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) 145 { 146 return pd ? container_of(pd, struct throtl_grp, pd) : NULL; 147 } 148 149 static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) 150 { 151 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); 152 } 153 154 /* 155 * Internal throttling interface 156 */ 157 #ifndef CONFIG_BLK_DEV_THROTTLING 158 static inline int blk_throtl_init(struct request_queue *q) { return 0; } 159 static inline void blk_throtl_exit(struct request_queue *q) { } 160 static inline void blk_throtl_register_queue(struct request_queue *q) { } 161 static inline void blk_throtl_charge_bio_split(struct bio *bio) { } 162 static inline bool blk_throtl_bio(struct bio *bio) { return false; } 163 #else /* CONFIG_BLK_DEV_THROTTLING */ 164 int blk_throtl_init(struct request_queue *q); 165 void blk_throtl_exit(struct request_queue *q); 166 void blk_throtl_register_queue(struct request_queue *q); 167 void blk_throtl_charge_bio_split(struct bio *bio); 168 bool __blk_throtl_bio(struct bio *bio); 169 static inline bool blk_throtl_bio(struct bio *bio) 170 { 171 struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg); 172 173 if (bio_flagged(bio, BIO_THROTTLED)) 174 return false; 175 if (!tg->has_rules[bio_data_dir(bio)]) 176 return false; 177 178 return __blk_throtl_bio(bio); 179 } 180 #endif /* CONFIG_BLK_DEV_THROTTLING */ 181 182 #endif 183