diff options
| -rw-r--r-- | block/blk-throttle.c | 53 |
1 files changed, 49 insertions, 4 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index c29a5a8..a62be8d 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -229,6 +229,22 @@ __throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg) } } +/* + * Should be called with without queue lock held. Here queue lock will be + * taken rarely. It will be taken only once during life time of a group + * if need be + */ +static void +throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg) +{ + if (!tg || tg->blkg.dev) + return; + + spin_lock_irq(td->queue->queue_lock); + __throtl_tg_fill_dev_details(td, tg); + spin_unlock_irq(td->queue->queue_lock); +} + static void throtl_init_add_tg_lists(struct throtl_data *td, struct throtl_grp *tg, struct blkio_cgroup *blkcg) { @@ -666,6 +682,12 @@ static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg, return 0; } +static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) { + if (tg->bps[rw] == -1 && tg->iops[rw] == -1) + return 1; + return 0; +} + /* * Returns whether one can dispatch a bio or not. Also returns approx number * of jiffies to wait before this bio is with-in IO rate and can be dispatched @@ -730,10 +752,6 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) tg->bytes_disp[rw] += bio->bi_size; tg->io_disp[rw]++; - /* - * TODO: This will take blkg->stats_lock. Figure out a way - * to avoid this cost. - */ blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, sync); } @@ -1111,12 +1129,39 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) struct throtl_grp *tg; struct bio *bio = *biop; bool rw = bio_data_dir(bio), update_disptime = true; + struct blkio_cgroup *blkcg; if (bio->bi_rw & REQ_THROTTLED) { bio->bi_rw &= ~REQ_THROTTLED; return 0; } + /* + * A throtl_grp pointer retrieved under rcu can be used to access + * basic fields like stats and io rates. If a group has no rules, + * just update the dispatch stats in lockless manner and return. + */ + + rcu_read_lock(); + blkcg = task_blkio_cgroup(current); + tg = throtl_find_tg(td, blkcg); + if (tg) { + throtl_tg_fill_dev_details(td, tg); + + if (tg_no_rule_group(tg, rw)) { + blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, + rw, bio->bi_rw & REQ_SYNC); + rcu_read_unlock(); + return 0; + } + } + rcu_read_unlock(); + + /* + * Either group has not been allocated yet or it is not an unlimited + * IO group + */ + spin_lock_irq(q->queue_lock); tg = throtl_get_tg(td); |
