[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>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index b06f20294ac0..fcaa4adefc82 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -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);