diff options
| -rw-r--r-- | block/blk-throttle.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 154bd63719c..ec9397f3eb0 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -46,6 +46,7 @@ struct throtl_service_queue { enum tg_state_flags { THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ + THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ }; #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) @@ -712,6 +713,15 @@ static void throtl_add_bio_tg(struct bio *bio, struct throtl_grp *tg, struct throtl_service_queue *sq = &tg->service_queue; bool rw = bio_data_dir(bio); + /* + * If @tg doesn't currently have any bios queued in the same + * direction, queueing @bio can change when @tg should be + * dispatched. Mark that @tg was empty. This is automatically + * cleaered on the next tg_update_disptime(). + */ + if (!sq->nr_queued[rw]) + tg->flags |= THROTL_TG_WAS_EMPTY; + bio_list_add(&sq->bio_lists[rw], bio); /* Take a bio reference on tg */ blkg_get(tg_to_blkg(tg)); @@ -740,6 +750,9 @@ static void tg_update_disptime(struct throtl_grp *tg, throtl_dequeue_tg(tg, parent_sq); tg->disptime = disptime; throtl_enqueue_tg(tg, parent_sq); + + /* see throtl_add_bio_tg() */ + tg->flags &= ~THROTL_TG_WAS_EMPTY; } static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw, @@ -1061,7 +1074,7 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) struct throtl_data *td = q->td; struct throtl_grp *tg; struct throtl_service_queue *sq; - bool rw = bio_data_dir(bio), update_disptime = true; + bool rw = bio_data_dir(bio); struct blkcg *blkcg; bool throttled = false; @@ -1097,16 +1110,10 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) sq = &tg->service_queue; - if (sq->nr_queued[rw]) { - /* - * There is already another bio queued in same dir. No - * need to update dispatch time. - */ - update_disptime = false; + /* throtl is FIFO - if other bios are already queued, should queue */ + if (sq->nr_queued[rw]) goto queue_bio; - } - /* Bio is with-in rate limit of group */ if (tg_may_dispatch(tg, bio, NULL)) { throtl_charge_bio(tg, bio); @@ -1138,7 +1145,8 @@ queue_bio: throtl_add_bio_tg(bio, tg, &q->td->service_queue); throttled = true; - if (update_disptime) { + /* update @tg's dispatch time if @tg was empty before @bio */ + if (tg->flags & THROTL_TG_WAS_EMPTY) { tg_update_disptime(tg, &td->service_queue); throtl_schedule_next_dispatch(td); } |