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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: Jesus Sanchez-Palencia <jesus.s.palencia@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesus Sanchez-Palencia 2018-11-14 17:26:33 -08:00 committed by David S. Miller
parent 3fcbdaee3b
commit 09fd4860ea
1 changed files with 12 additions and 9 deletions
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21
net/sched/sch_etf.c
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@ -30,7 +30,7 @@ struct etf_sched_data {
int queue; int queue;
s32 delta; /* in ns */ s32 delta; /* in ns */
ktime_t last; /* The txtime of the last skb sent to the netdevice. */ 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; struct qdisc_watchdog watchdog;
ktime_t (*get_time)(void); 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 etf_sched_data *q = qdisc_priv(sch);
struct rb_node *p; struct rb_node *p;
p = rb_first(&q->head); p = rb_first_cached(&q->head);
if (!p) if (!p)
return NULL; return NULL;
@ -156,8 +156,9 @@ static int etf_enqueue_timesortedlist(struct sk_buff *nskb, struct Qdisc *sch,
struct sk_buff **to_free) struct sk_buff **to_free)
{ {
struct etf_sched_data *q = qdisc_priv(sch); 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; ktime_t txtime = nskb->tstamp;
bool leftmost = true;
if (!is_packet_valid(sch, nskb)) { if (!is_packet_valid(sch, nskb)) {
report_sock_error(nskb, EINVAL, report_sock_error(nskb, EINVAL,
@ -170,13 +171,15 @@ static int etf_enqueue_timesortedlist(struct sk_buff *nskb, struct Qdisc *sch,
parent = *p; parent = *p;
skb = rb_to_skb(parent); skb = rb_to_skb(parent);
if (ktime_after(txtime, skb->tstamp)) if (ktime_after(txtime, skb->tstamp)) {
p = &parent->rb_right; p = &parent->rb_right;
else leftmost = false;
} else {
p = &parent->rb_left; p = &parent->rb_left;
} }
}
rb_link_node(&nskb->rbnode, parent, p); 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); qdisc_qstats_backlog_inc(sch, nskb);
sch->q.qlen++; 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); 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 /* The rbnode field in the skb re-uses these fields, now that
* we are done with the rbnode, reset them. * 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) static void timesortedlist_clear(struct Qdisc *sch)
{ {
struct etf_sched_data *q = qdisc_priv(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) { while (p) {
struct sk_buff *skb = rb_to_skb(p); struct sk_buff *skb = rb_to_skb(p);
p = rb_next(p); p = rb_next(p);
rb_erase(&skb->rbnode, &q->head); rb_erase_cached(&skb->rbnode, &q->head);
rtnl_kfree_skbs(skb, skb); rtnl_kfree_skbs(skb, skb);
sch->q.qlen--; sch->q.qlen--;
} }