etf: Drop all expired packets (37342bda) · Commits · 戴 / test

Currently on dequeue() ETF only drops the first expired packet, which causes a problem if the next packet is already expired. When this happens, the watchdog will be configured with a time in the past, fire straight way and the packet will finally be dropped once the dequeue() function of the qdisc is called again. We can save quite a few cycles and improve the overall behavior of the qdisc if we drop all expired packets if the next packet is expired. This should allow ETF to recover faster from bad situations. But packet drops are still a very serious warning that the requirements imposed on the system aren't reasonable. This was inspired by how the implementation of hrtimers use the rb_tree inside the kernel. Signed-off-by:

Jesus Sanchez-Palencia <jesus.s.palencia@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/sched/sch_etf.c

+21 −15

Original line number	Diff line number	Diff line
		@@ -190,10 +190,16 @@ static int etf_enqueue_timesortedlist(struct sk_buff nskb, struct Qdisc sch,
		return NET_XMIT_SUCCESS;
		}

		static void timesortedlist_drop(struct Qdisc sch, struct sk_buff skb)
		static void timesortedlist_drop(struct Qdisc sch, struct sk_buff skb,
		ktime_t now)
		{
		struct etf_sched_data *q = qdisc_priv(sch);
		struct sk_buff *to_free = NULL;
		struct sk_buff *tmp = NULL;

		skb_rbtree_walk_from_safe(skb, tmp) {
		if (ktime_after(skb->tstamp, now))
		break;

		rb_erase_cached(&skb->rbnode, &q->head);

		@@ -204,17 +210,17 @@ static void timesortedlist_drop(struct Qdisc sch, struct sk_buff skb)
		skb->prev = NULL;
		skb->dev = qdisc_dev(sch);

		qdisc_qstats_backlog_dec(sch, skb);

		report_sock_error(skb, ECANCELED, SO_EE_CODE_TXTIME_MISSED);

		qdisc_qstats_backlog_dec(sch, skb);
		qdisc_drop(skb, sch, &to_free);
		kfree_skb_list(to_free);
		qdisc_qstats_overlimit(sch);

		sch->q.qlen--;
		}

		kfree_skb_list(to_free);
		}

		static void timesortedlist_remove(struct Qdisc sch, struct sk_buff skb)
		{
		struct etf_sched_data *q = qdisc_priv(sch);
		@@ -251,7 +257,7 @@ static struct sk_buff etf_dequeue_timesortedlist(struct Qdisc sch)

		/* Drop if packet has expired while in queue. */
		if (ktime_before(skb->tstamp, now)) {
		timesortedlist_drop(sch, skb);
		timesortedlist_drop(sch, skb, now);
		skb = NULL;
		goto out;
		}

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