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 enum { 62 LIMIT_LOW, 63 LIMIT_MAX, 64 LIMIT_CNT, 65 }; 66 67 struct 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 uint64_t carryover_bytes[2]; 131 unsigned 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 }; 154 155 extern struct blkcg_policy blkcg_policy_throtl; 156 157 static 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 } 161 162 static 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 171 static inline int blk_throtl_init(struct gendisk *disk) { return 0; } 172 static inline void blk_throtl_exit(struct gendisk *disk) { } 173 static inline void blk_throtl_register(struct gendisk *disk) { } 174 static inline bool blk_throtl_bio(struct bio *bio) { return false; } 175 static inline void blk_throtl_cancel_bios(struct gendisk *disk) { } 176 #else /* CONFIG_BLK_DEV_THROTTLING */ 177 int blk_throtl_init(struct gendisk *disk); 178 void blk_throtl_exit(struct gendisk *disk); 179 void blk_throtl_register(struct gendisk *disk); 180 bool __blk_throtl_bio(struct bio *bio); 181 void blk_throtl_cancel_bios(struct gendisk *disk); 182 183 static 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 /* iops limit is always counted */ 189 if (tg->has_rules_iops[rw]) 190 return true; 191 192 if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED)) 193 return true; 194 195 return false; 196 } 197 198 static inline bool blk_throtl_bio(struct bio *bio) 199 { 200 201 if (!blk_should_throtl(bio)) 202 return false; 203 204 return __blk_throtl_bio(bio); 205 } 206 #endif /* CONFIG_BLK_DEV_THROTTLING */ 207 208 #endif 209