Currently taprio assumes that the budget for a traffic class expires at
the end of the current interval as if the next interval contains a "gate
close" event for this traffic class.
This is, however, an unfounded assumption. Allow schedule entry
intervals to be fused together for a particular traffic class by
calculating the budget until the gate *actually* closes.
This means we need to keep budgets per traffic class, and we also need
to update the budget consumption procedure.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
---
v1->v2: none
net/sched/sch_taprio.c | 54 +++++++++++++++++++++++++++++++++++-------
1 file changed, 46 insertions(+), 8 deletions(-)
@@ -43,6 +43,7 @@ struct sched_entry {
* respective traffic class gate closes
*/
u64 gate_duration[TC_MAX_QUEUE];
+ atomic_t budget[TC_MAX_QUEUE];
struct list_head list;
/* The instant that this entry ends and the next one
@@ -51,7 +52,6 @@ struct sched_entry {
*/
ktime_t end_time;
ktime_t next_txtime;
- atomic_t budget;
int index;
u32 gate_mask;
u32 interval;
@@ -563,11 +563,48 @@ static struct sk_buff *taprio_peek(struct Qdisc *sch)
return NULL;
}
-static void taprio_set_budget(struct taprio_sched *q, struct sched_entry *entry)
+static void taprio_set_budgets(struct taprio_sched *q,
+ struct sched_gate_list *sched,
+ struct sched_entry *entry)
{
- atomic_set(&entry->budget,
- div64_u64((u64)entry->interval * PSEC_PER_NSEC,
- atomic64_read(&q->picos_per_byte)));
+ struct net_device *dev = qdisc_dev(q->root);
+ int num_tc = netdev_get_num_tc(dev);
+ int tc, budget;
+
+ for (tc = 0; tc < num_tc; tc++) {
+ /* Traffic classes which never close have infinite budget */
+ if (entry->gate_duration[tc] == sched->cycle_time)
+ budget = INT_MAX;
+ else
+ budget = div64_u64((u64)entry->gate_duration[tc] * PSEC_PER_NSEC,
+ atomic64_read(&q->picos_per_byte));
+
+ atomic_set(&entry->budget[tc], budget);
+ }
+}
+
+/* When an skb is sent, it consumes from the budget of all traffic classes */
+static int taprio_update_budgets(struct sched_entry *entry, size_t len,
+ int tc_consumed, int num_tc)
+{
+ int tc, budget, new_budget = 0;
+
+ for (tc = 0; tc < num_tc; tc++) {
+ budget = atomic_read(&entry->budget[tc]);
+ /* Don't consume from infinite budget */
+ if (budget == INT_MAX) {
+ if (tc == tc_consumed)
+ new_budget = budget;
+ continue;
+ }
+
+ if (tc == tc_consumed)
+ new_budget = atomic_sub_return(len, &entry->budget[tc]);
+ else
+ atomic_sub(len, &entry->budget[tc]);
+ }
+
+ return new_budget;
}
static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq,
@@ -577,6 +614,7 @@ static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq,
struct taprio_sched *q = qdisc_priv(sch);
struct net_device *dev = qdisc_dev(sch);
struct Qdisc *child = q->qdiscs[txq];
+ int num_tc = netdev_get_num_tc(dev);
struct sk_buff *skb;
ktime_t guard;
int prio;
@@ -611,7 +649,7 @@ static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq,
/* ... and no budget. */
if (gate_mask != TAPRIO_ALL_GATES_OPEN &&
- atomic_sub_return(len, &entry->budget) < 0)
+ taprio_update_budgets(entry, len, tc, num_tc) < 0)
return NULL;
skip_peek_checks:
@@ -832,7 +870,7 @@ static enum hrtimer_restart advance_sched(struct hrtimer *timer)
}
next->end_time = end_time;
- taprio_set_budget(q, next);
+ taprio_set_budgets(q, oper, next);
first_run:
rcu_assign_pointer(q->current_entry, next);
@@ -1091,7 +1129,7 @@ static void setup_first_end_time(struct taprio_sched *q,
sched->cycle_end_time = ktime_add_ns(base, cycle);
first->end_time = ktime_add_ns(base, first->interval);
- taprio_set_budget(q, first);
+ taprio_set_budgets(q, sched, first);
rcu_assign_pointer(q->current_entry, NULL);
}