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-rw-r--r--block/blk-throttle.c100
1 files changed, 96 insertions, 4 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 1fade5078fc1..dd382d849c39 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -457,6 +457,7 @@ static void blk_throtl_update_limit_valid(struct throtl_data *td)
td->limit_valid[LIMIT_LOW] = low_valid;
}
+static void throtl_upgrade_state(struct throtl_data *td);
static void throtl_pd_offline(struct blkg_policy_data *pd)
{
struct throtl_grp *tg = pd_to_tg(pd);
@@ -468,9 +469,8 @@ static void throtl_pd_offline(struct blkg_policy_data *pd)
blk_throtl_update_limit_valid(tg->td);
- if (tg->td->limit_index == LIMIT_LOW &&
- !tg->td->limit_valid[LIMIT_LOW])
- tg->td->limit_index = LIMIT_MAX;
+ if (!tg->td->limit_valid[tg->td->limit_index])
+ throtl_upgrade_state(tg->td);
}
static void throtl_pd_free(struct blkg_policy_data *pd)
@@ -1081,6 +1081,8 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
return nr_disp;
}
+static bool throtl_can_upgrade(struct throtl_data *td,
+ struct throtl_grp *this_tg);
/**
* throtl_pending_timer_fn - timer function for service_queue->pending_timer
* @arg: the throtl_service_queue being serviced
@@ -1107,6 +1109,9 @@ static void throtl_pending_timer_fn(unsigned long arg)
int ret;
spin_lock_irq(q->queue_lock);
+ if (throtl_can_upgrade(td, NULL))
+ throtl_upgrade_state(td);
+
again:
parent_sq = sq->parent_sq;
dispatched = false;
@@ -1522,6 +1527,87 @@ static struct blkcg_policy blkcg_policy_throtl = {
.pd_free_fn = throtl_pd_free,
};
+static bool throtl_tg_can_upgrade(struct throtl_grp *tg)
+{
+ struct throtl_service_queue *sq = &tg->service_queue;
+ bool read_limit, write_limit;
+
+ /*
+ * if cgroup reaches low limit (if low limit is 0, the cgroup always
+ * reaches), it's ok to upgrade to next limit
+ */
+ read_limit = tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW];
+ write_limit = tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW];
+ if (!read_limit && !write_limit)
+ return true;
+ if (read_limit && sq->nr_queued[READ] &&
+ (!write_limit || sq->nr_queued[WRITE]))
+ return true;
+ if (write_limit && sq->nr_queued[WRITE] &&
+ (!read_limit || sq->nr_queued[READ]))
+ return true;
+ return false;
+}
+
+static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg)
+{
+ while (true) {
+ if (throtl_tg_can_upgrade(tg))
+ return true;
+ tg = sq_to_tg(tg->service_queue.parent_sq);
+ if (!tg || !tg_to_blkg(tg)->parent)
+ return false;
+ }
+ return false;
+}
+
+static bool throtl_can_upgrade(struct throtl_data *td,
+ struct throtl_grp *this_tg)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg;
+
+ if (td->limit_index != LIMIT_LOW)
+ return false;
+
+ rcu_read_lock();
+ blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
+ if (tg == this_tg)
+ continue;
+ if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children))
+ continue;
+ if (!throtl_hierarchy_can_upgrade(tg)) {
+ rcu_read_unlock();
+ return false;
+ }
+ }
+ rcu_read_unlock();
+ return true;
+}
+
+static void throtl_upgrade_state(struct throtl_data *td)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg;
+
+ td->limit_index = LIMIT_MAX;
+ rcu_read_lock();
+ blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+ struct throtl_service_queue *sq = &tg->service_queue;
+
+ tg->disptime = jiffies - 1;
+ throtl_select_dispatch(sq);
+ throtl_schedule_next_dispatch(sq, false);
+ }
+ rcu_read_unlock();
+ throtl_select_dispatch(&td->service_queue);
+ throtl_schedule_next_dispatch(&td->service_queue, false);
+ queue_work(kthrotld_workqueue, &td->dispatch_work);
+}
+
bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
struct bio *bio)
{
@@ -1544,14 +1630,20 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
sq = &tg->service_queue;
+again:
while (true) {
/* throtl is FIFO - if bios are already queued, should queue */
if (sq->nr_queued[rw])
break;
/* if above limits, break to queue */
- if (!tg_may_dispatch(tg, bio, NULL))
+ if (!tg_may_dispatch(tg, bio, NULL)) {
+ if (throtl_can_upgrade(tg->td, tg)) {
+ throtl_upgrade_state(tg->td);
+ goto again;
+ }
break;
+ }
/* within limits, let's charge and dispatch directly */
throtl_charge_bio(tg, bio);