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net_sched: remove generic throttled management

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__QDISC_STATE_THROTTLED bit manipulation is rather expensive
for HTB and few others.

I already removed it for sch_fq in commit f2600cf02b
("net: sched: avoid costly atomic operation in fq_dequeue()")
and so far nobody complained.

When one ore more packets are stuck in one or more throttled
HTB class, a htb dequeue() performs two atomic operations
to clear/set __QDISC_STATE_THROTTLED bit, while root qdisc
lock is held.

Removing this pair of atomic operations bring me a 8 % performance
increase on 200 TCP_RR tests, in presence of throttled classes.

This patch has no side effect, since nothing actually uses
disc_is_throttled() anymore.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2016-06-10 16:41:39 -07:00
committed by David S. Miller
parent 42117927ca
commit 45f50bed1d
9 changed files with 6 additions and 35 deletions
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7
net/sched/sch_api.c
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@@ -583,7 +583,6 @@ static enum hrtimer_restart qdisc_watchdog(struct hrtimer *timer)
timer);
rcu_read_lock();
qdisc_unthrottled(wd->qdisc);
__netif_schedule(qdisc_root(wd->qdisc));
rcu_read_unlock();
@@ -598,15 +597,12 @@ void qdisc_watchdog_init(struct qdisc_watchdog *wd, struct Qdisc *qdisc)
}
EXPORT_SYMBOL(qdisc_watchdog_init);
void qdisc_watchdog_schedule_ns(struct qdisc_watchdog *wd, u64 expires, bool throttle)
void qdisc_watchdog_schedule_ns(struct qdisc_watchdog *wd, u64 expires)
{
if (test_bit(__QDISC_STATE_DEACTIVATED,
&qdisc_root_sleeping(wd->qdisc)->state))
return;
if (throttle)
qdisc_throttled(wd->qdisc);
if (wd->last_expires == expires)
return;
@@ -620,7 +616,6 @@ EXPORT_SYMBOL(qdisc_watchdog_schedule_ns);
void qdisc_watchdog_cancel(struct qdisc_watchdog *wd)
{
hrtimer_cancel(&wd->timer);
qdisc_unthrottled(wd->qdisc);
}
EXPORT_SYMBOL(qdisc_watchdog_cancel);