Commit 09fd4860 authored by Jesus Sanchez-Palencia's avatar Jesus Sanchez-Palencia Committed by David S. Miller
Browse files

etf: Use cached rb_root 



ETF's peek() operation is heavily used so use an rb_root_cached instead
and leverage rb_first_cached() which will run in O(1) instead of
O(log n).

Even if on 'timesortedlist_clear()' we could be using rb_erase(), we
choose to use rb_erase_cached(), because if in the future we allow
runtime changes to ETF parameters, and need to do a '_clear()', this
might cause some hard to debug issues.

Signed-off-by: default avatarJesus Sanchez-Palencia <jesus.s.palencia@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3fcbdaee

net/sched/sch_etf.c

+12 −9
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ struct etf_sched_data { 
	int queue;

	s32 delta; /* in ns */

	ktime_t last; /* The txtime of the last skb sent to the netdevice. */

	struct rb_root head;

	struct rb_root_cached head;

	struct qdisc_watchdog watchdog;

	ktime_t (*get_time)(void);

};
@@ -104,7 +104,7 @@ static struct sk_buff *etf_peek_timesortedlist(struct Qdisc *sch) 
	struct etf_sched_data *q = qdisc_priv(sch);

	struct rb_node *p;



	p = rb_first(&q->head);

	p = rb_first_cached(&q->head);

	if (!p)

		return NULL;
@@ -156,8 +156,9 @@ static int etf_enqueue_timesortedlist(struct sk_buff *nskb, struct Qdisc *sch, 
				      struct sk_buff **to_free)

{

	struct etf_sched_data *q = qdisc_priv(sch);

	struct rb_node **p = &q->head.rb_node, *parent = NULL;

	struct rb_node **p = &q->head.rb_root.rb_node, *parent = NULL;

	ktime_t txtime = nskb->tstamp;

	bool leftmost = true;



	if (!is_packet_valid(sch, nskb)) {

		report_sock_error(nskb, EINVAL,
@@ -170,13 +171,15 @@ static int etf_enqueue_timesortedlist(struct sk_buff *nskb, struct Qdisc *sch, 


		parent = *p;

		skb = rb_to_skb(parent);

		if (ktime_after(txtime, skb->tstamp))

		if (ktime_after(txtime, skb->tstamp)) {

			p = &parent->rb_right;

		else

			leftmost = false;

		} else {

			p = &parent->rb_left;

		}

	}

	rb_link_node(&nskb->rbnode, parent, p);

	rb_insert_color(&nskb->rbnode, &q->head);

	rb_insert_color_cached(&nskb->rbnode, &q->head, leftmost);



	qdisc_qstats_backlog_inc(sch, nskb);

	sch->q.qlen++;
@@ -192,7 +195,7 @@ static void timesortedlist_erase(struct Qdisc *sch, struct sk_buff *skb, 
{

	struct etf_sched_data *q = qdisc_priv(sch);



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

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



	/* The rbnode field in the skb re-uses these fields, now that

	 * we are done with the rbnode, reset them.
@@ -388,14 +391,14 @@ static int etf_init(struct Qdisc *sch, struct nlattr *opt, 
static void timesortedlist_clear(struct Qdisc *sch)

{

	struct etf_sched_data *q = qdisc_priv(sch);

	struct rb_node *p = rb_first(&q->head);

	struct rb_node *p = rb_first_cached(&q->head);



	while (p) {

		struct sk_buff *skb = rb_to_skb(p);



		p = rb_next(p);



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

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

		rtnl_kfree_skbs(skb, skb);

		sch->q.qlen--;

	}

CRA Git | Maintained and supported by SUSTech CRA and CCSE