net_sched: sch_htb: add per class overlimits counter

Eric Dumazet · davem330 · commit 3c75f6ee139d · 2017-09-18T19:12:14.000-07:00
HTB qdisc overlimits counter is properly increased, but we have no per
class counter, meaning it is difficult to diagnose HTB problems.

This patch adds this counter, visible in "tc -s class show dev eth0",
with current iproute2.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: Denys Fedoryshchenko &lt;nuclearcat@nuclearcat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
@@ -142,6 +142,7 @@ struct htb_class {
 	struct rb_node		node[TC_HTB_NUMPRIO];	/* node for self or feed tree */
 
 	unsigned int drops ____cacheline_aligned_in_smp;
+	unsigned int		overlimits;
 };
 
 struct htb_level {
@@ -533,6 +534,9 @@ htb_change_class_mode(struct htb_sched *q, struct htb_class *cl, s64 *diff)
 	if (new_mode == cl->cmode)
 		return;
 
+	if (new_mode == HTB_CANT_SEND)
+		cl->overlimits++;
+
 	if (cl->prio_activity) {	/* not necessary: speed optimization */
 		if (cl->cmode != HTB_CANT_SEND)
 			htb_deactivate_prios(q, cl);
@@ -1143,6 +1147,7 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
 	struct htb_class *cl = (struct htb_class *)arg;
 	struct gnet_stats_queue qs = {
 		.drops = cl->drops,
+		.overlimits = cl->overlimits,
 	};
 	__u32 qlen = 0;
 
