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[NETEM]: avoid excessive requeues 

The netem code would call getnstimeofday() and dequeue/requeue after
every packet, even if it was waiting. Avoid this overhead by using
the throttled flag.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2007-03-22 12:17:42 -07:00 committed by David S. Miller
parent 075aa573b7
commit 11274e5a43
2 changed files with 16 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
net/sched/sch_api.c
View File

@ -298,6 +298,7 @@ static enum hrtimer_restart qdisc_watchdog(struct hrtimer *timer)
timer); timer);
wd->qdisc->flags &= ~TCQ_F_THROTTLED; wd->qdisc->flags &= ~TCQ_F_THROTTLED;
smp_wmb();
netif_schedule(wd->qdisc->dev); netif_schedule(wd->qdisc->dev);
return HRTIMER_NORESTART; return HRTIMER_NORESTART;
} }
@ -315,6 +316,7 @@ void qdisc_watchdog_schedule(struct qdisc_watchdog *wd, psched_time_t expires)
ktime_t time; ktime_t time;
wd->qdisc->flags |= TCQ_F_THROTTLED; wd->qdisc->flags |= TCQ_F_THROTTLED;
smp_wmb();
time = ktime_set(0, 0); time = ktime_set(0, 0);
time = ktime_add_ns(time, PSCHED_US2NS(expires)); time = ktime_add_ns(time, PSCHED_US2NS(expires));
hrtimer_start(&wd->timer, time, HRTIMER_MODE_ABS); hrtimer_start(&wd->timer, time, HRTIMER_MODE_ABS);
@ -325,6 +327,7 @@ void qdisc_watchdog_cancel(struct qdisc_watchdog *wd)
{ {
hrtimer_cancel(&wd->timer); hrtimer_cancel(&wd->timer);
wd->qdisc->flags &= ~TCQ_F_THROTTLED; wd->qdisc->flags &= ~TCQ_F_THROTTLED;
smp_wmb();
} }
EXPORT_SYMBOL(qdisc_watchdog_cancel); EXPORT_SYMBOL(qdisc_watchdog_cancel);

15
net/sched/sch_netem.c
View File

@ -273,6 +273,10 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
struct netem_sched_data *q = qdisc_priv(sch); struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb; struct sk_buff *skb;
smp_mb();
if (sch->flags & TCQ_F_THROTTLED)
return NULL;
skb = q->qdisc->dequeue(q->qdisc); skb = q->qdisc->dequeue(q->qdisc);
if (skb) { if (skb) {
const struct netem_skb_cb *cb const struct netem_skb_cb *cb
@ -285,18 +289,17 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
if (PSCHED_TLESS(cb->time_to_send, now)) { if (PSCHED_TLESS(cb->time_to_send, now)) {
pr_debug("netem_dequeue: return skb=%p\n", skb); pr_debug("netem_dequeue: return skb=%p\n", skb);
sch->q.qlen--; sch->q.qlen--;
sch->flags &= ~TCQ_F_THROTTLED;
return skb; return skb;
} else { }
qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) { if (unlikely(q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS)) {
qdisc_tree_decrease_qlen(q->qdisc, 1); qdisc_tree_decrease_qlen(q->qdisc, 1);
sch->qstats.drops++; sch->qstats.drops++;
printk(KERN_ERR "netem: queue discpline %s could not requeue\n", printk(KERN_ERR "netem: %s could not requeue\n",
q->qdisc->ops->id); q->qdisc->ops->id);
} }
}
qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
} }
return NULL; return NULL;