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-rw-r--r--block/blk-throttle.c53
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);
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