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>

1 files changed, 2 insertions, 4 deletions

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index c9b9fcb53206..cbd7e1fd23b4 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -377,7 +377,6 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
                 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 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
         if (unlikely(f == &q->internal)) {
                 q->stat_internal_packets++;
-                qdisc_unthrottled(sch);
         }
         sch->q.qlen++;
 
@@ -433,7 +431,8 @@ begin:
                 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 @@ begin:
         }
 out:
         qdisc_bstats_update(sch, skb);
-        qdisc_unthrottled(sch);
         return skb;
 }