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Diffstat (limited to 'block/blk-throttle.h')
| -rw-r--r-- | block/blk-throttle.h | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/block/blk-throttle.h b/block/blk-throttle.h new file mode 100644 index 000000000000..175f03abd9e4 --- /dev/null +++ b/block/blk-throttle.h @@ -0,0 +1,182 @@ +#ifndef BLK_THROTTLE_H +#define BLK_THROTTLE_H + +#include "blk-cgroup-rwstat.h" + +/* + * To implement hierarchical throttling, throtl_grps form a tree and bios + * are dispatched upwards level by level until they reach the top and get + * issued. When dispatching bios from the children and local group at each + * level, if the bios are dispatched into a single bio_list, there's a risk + * of a local or child group which can queue many bios at once filling up + * the list starving others. + * + * To avoid such starvation, dispatched bios are queued separately + * according to where they came from. When they are again dispatched to + * the parent, they're popped in round-robin order so that no single source + * hogs the dispatch window. + * + * throtl_qnode is used to keep the queued bios separated by their sources. + * Bios are queued to throtl_qnode which in turn is queued to + * throtl_service_queue and then dispatched in round-robin order. + * + * It's also used to track the reference counts on blkg's. A qnode always + * belongs to a throtl_grp and gets queued on itself or the parent, so + * incrementing the reference of the associated throtl_grp when a qnode is + * queued and decrementing when dequeued is enough to keep the whole blkg + * tree pinned while bios are in flight. + */ +struct throtl_qnode { + struct list_head node; /* service_queue->queued[] */ + struct bio_list bios; /* queued bios */ + struct throtl_grp *tg; /* tg this qnode belongs to */ +}; + +struct throtl_service_queue { + struct throtl_service_queue *parent_sq; /* the parent service_queue */ + + /* + * Bios queued directly to this service_queue or dispatched from + * children throtl_grp's. + */ + struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ + unsigned int nr_queued[2]; /* number of queued bios */ + + /* + * RB tree of active children throtl_grp's, which are sorted by + * their ->disptime. + */ + struct rb_root_cached pending_tree; /* RB tree of active tgs */ + unsigned int nr_pending; /* # queued in the tree */ + unsigned long first_pending_disptime; /* disptime of the first tg */ + struct timer_list pending_timer; /* fires on first_pending_disptime */ +}; + +enum { + LIMIT_LOW, + LIMIT_MAX, + LIMIT_CNT, +}; + +struct throtl_grp { + /* must be the first member */ + struct blkg_policy_data pd; + + /* active throtl group service_queue member */ + struct rb_node rb_node; + + /* throtl_data this group belongs to */ + struct throtl_data *td; + + /* this group's service queue */ + struct throtl_service_queue service_queue; + + /* + * qnode_on_self is used when bios are directly queued to this + * throtl_grp so that local bios compete fairly with bios + * dispatched from children. qnode_on_parent is used when bios are + * dispatched from this throtl_grp into its parent and will compete + * with the sibling qnode_on_parents and the parent's + * qnode_on_self. + */ + struct throtl_qnode qnode_on_self[2]; + struct throtl_qnode qnode_on_parent[2]; + + /* + * Dispatch time in jiffies. This is the estimated time when group + * will unthrottle and is ready to dispatch more bio. It is used as + * key to sort active groups in service tree. + */ + unsigned long disptime; + + unsigned int flags; + + /* are there any throtl rules between this group and td? */ + bool has_rules[2]; + + /* internally used bytes per second rate limits */ + uint64_t bps[2][LIMIT_CNT]; + /* user configured bps limits */ + uint64_t bps_conf[2][LIMIT_CNT]; + + /* internally used IOPS limits */ + unsigned int iops[2][LIMIT_CNT]; + /* user configured IOPS limits */ + unsigned int iops_conf[2][LIMIT_CNT]; + + /* Number of bytes dispatched in current slice */ + uint64_t bytes_disp[2]; + /* Number of bio's dispatched in current slice */ + unsigned int io_disp[2]; + + unsigned long last_low_overflow_time[2]; + + uint64_t last_bytes_disp[2]; + unsigned int last_io_disp[2]; + + unsigned long last_check_time; + + unsigned long latency_target; /* us */ + unsigned long latency_target_conf; /* us */ + /* When did we start a new slice */ + unsigned long slice_start[2]; + unsigned long slice_end[2]; + + unsigned long last_finish_time; /* ns / 1024 */ + unsigned long checked_last_finish_time; /* ns / 1024 */ + unsigned long avg_idletime; /* ns / 1024 */ + unsigned long idletime_threshold; /* us */ + unsigned long idletime_threshold_conf; /* us */ + + unsigned int bio_cnt; /* total bios */ + unsigned int bad_bio_cnt; /* bios exceeding latency threshold */ + unsigned long bio_cnt_reset_time; + + atomic_t io_split_cnt[2]; + atomic_t last_io_split_cnt[2]; + + struct blkg_rwstat stat_bytes; + struct blkg_rwstat stat_ios; +}; + +extern struct blkcg_policy blkcg_policy_throtl; + +static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) +{ + return pd ? container_of(pd, struct throtl_grp, pd) : NULL; +} + +static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) +{ + return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); +} + +/* + * Internal throttling interface + */ +#ifndef CONFIG_BLK_DEV_THROTTLING +static inline int blk_throtl_init(struct request_queue *q) { return 0; } +static inline void blk_throtl_exit(struct request_queue *q) { } +static inline void blk_throtl_register_queue(struct request_queue *q) { } +static inline void blk_throtl_charge_bio_split(struct bio *bio) { } +static inline bool blk_throtl_bio(struct bio *bio) { return false; } +#else /* CONFIG_BLK_DEV_THROTTLING */ +int blk_throtl_init(struct request_queue *q); +void blk_throtl_exit(struct request_queue *q); +void blk_throtl_register_queue(struct request_queue *q); +void blk_throtl_charge_bio_split(struct bio *bio); +bool __blk_throtl_bio(struct bio *bio); +static inline bool blk_throtl_bio(struct bio *bio) +{ + struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg); + + if (bio_flagged(bio, BIO_THROTTLED)) + return false; + if (!tg->has_rules[bio_data_dir(bio)]) + return false; + + return __blk_throtl_bio(bio); +} +#endif /* CONFIG_BLK_DEV_THROTTLING */ + +#endif |