提交 11274e5a 编写于 作者: S Stephen Hemminger 提交者: David S. Miller

[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: NStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
上级 075aa573
......@@ -298,6 +298,7 @@ static enum hrtimer_restart qdisc_watchdog(struct hrtimer *timer)
timer);
wd->qdisc->flags &= ~TCQ_F_THROTTLED;
smp_wmb();
netif_schedule(wd->qdisc->dev);
return HRTIMER_NORESTART;
}
......@@ -315,6 +316,7 @@ void qdisc_watchdog_schedule(struct qdisc_watchdog *wd, psched_time_t expires)
ktime_t time;
wd->qdisc->flags |= TCQ_F_THROTTLED;
smp_wmb();
time = ktime_set(0, 0);
time = ktime_add_ns(time, PSCHED_US2NS(expires));
hrtimer_start(&wd->timer, time, HRTIMER_MODE_ABS);
......@@ -325,6 +327,7 @@ void qdisc_watchdog_cancel(struct qdisc_watchdog *wd)
{
hrtimer_cancel(&wd->timer);
wd->qdisc->flags &= ~TCQ_F_THROTTLED;
smp_wmb();
}
EXPORT_SYMBOL(qdisc_watchdog_cancel);
......
......@@ -273,6 +273,10 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
smp_mb();
if (sch->flags & TCQ_F_THROTTLED)
return NULL;
skb = q->qdisc->dequeue(q->qdisc);
if (skb) {
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)) {
pr_debug("netem_dequeue: return skb=%p\n", skb);
sch->q.qlen--;
sch->flags &= ~TCQ_F_THROTTLED;
return skb;
} else {
qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
qdisc_tree_decrease_qlen(q->qdisc, 1);
sch->qstats.drops++;
printk(KERN_ERR "netem: queue discpline %s could not requeue\n",
q->qdisc->ops->id);
}
}
if (unlikely(q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS)) {
qdisc_tree_decrease_qlen(q->qdisc, 1);
sch->qstats.drops++;
printk(KERN_ERR "netem: %s could not requeue\n",
q->qdisc->ops->id);
}
qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
}
return NULL;
......
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