net: sched: avoid costly atomic operation in fq_dequeue()
Standard qdisc API to setup a timer implies an atomic operation on every
packet dequeue : qdisc_unthrottled()
It turns out this is not really needed for FQ, as FQ has no concept of
global qdisc throttling, being a qdisc handling many different flows,
some of them can be throttled, while others are not.
Fix is straightforward : add a 'bool throttle' to
qdisc_watchdog_schedule_ns(), and remove calls to qdisc_unthrottled()
in sch_fq.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index c79a226..2cf61b3 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -594,13 +594,14 @@
}
EXPORT_SYMBOL(qdisc_watchdog_init);
-void qdisc_watchdog_schedule_ns(struct qdisc_watchdog *wd, u64 expires)
+void qdisc_watchdog_schedule_ns(struct qdisc_watchdog *wd, u64 expires, bool throttle)
{
if (test_bit(__QDISC_STATE_DEACTIVATED,
&qdisc_root_sleeping(wd->qdisc)->state))
return;
- qdisc_throttled(wd->qdisc);
+ if (throttle)
+ qdisc_throttled(wd->qdisc);
hrtimer_start(&wd->timer,
ns_to_ktime(expires),
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index c9b9fcb..cbd7e1f 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -377,7 +377,6 @@
if (time_after(jiffies, f->age + q->flow_refill_delay))
f->credit = max_t(u32, f->credit, q->quantum);
q->inactive_flows--;
- qdisc_unthrottled(sch);
}
/* Note: this overwrites f->age */
@@ -385,7 +384,6 @@
if (unlikely(f == &q->internal)) {
q->stat_internal_packets++;
- qdisc_unthrottled(sch);
}
sch->q.qlen++;
@@ -433,7 +431,8 @@
if (!head->first) {
if (q->time_next_delayed_flow != ~0ULL)
qdisc_watchdog_schedule_ns(&q->watchdog,
- q->time_next_delayed_flow);
+ q->time_next_delayed_flow,
+ false);
return NULL;
}
}
@@ -495,7 +494,6 @@
}
out:
qdisc_bstats_update(sch, skb);
- qdisc_unthrottled(sch);
return skb;
}
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 77edffe..a4afde1 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -268,7 +268,8 @@
}
qdisc_watchdog_schedule_ns(&q->watchdog,
- now + max_t(long, -toks, -ptoks));
+ now + max_t(long, -toks, -ptoks),
+ true);
/* Maybe we have a shorter packet in the queue,
which can be sent now. It sounds cool,