From: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
Recently we introduced a Qdisc backpressure infrastructure (currently
supports UDP sockets). Use it in CBQ Qdisc.
Tested with 500 Mbits/sec rate limit using 16 iperf UDP 1 Gbit/sec
clients. Before:
[ 3] 0.0-15.0 sec 55.8 MBytes 31.2 Mbits/sec 1.185 ms 1073326/1113110 (96%)
[ 3] 0.0-15.0 sec 55.9 MBytes 31.3 Mbits/sec 1.001 ms 1080330/1120201 (96%)
[ 3] 0.0-15.0 sec 55.6 MBytes 31.1 Mbits/sec 1.750 ms 1078292/1117980 (96%)
[ 3] 0.0-15.0 sec 55.3 MBytes 30.9 Mbits/sec 0.895 ms 1089200/1128640 (97%)
<...> ^^^^^^^^^^^^^^^^^^^^^
Total throughput is 493.7 Mbits/sec and average drop rate is 96.13%.
Now enable Qdisc backpressure for UDP sockets, with
udp_backpressure_interval default to 100 milliseconds:
[ 3] 0.0-15.0 sec 54.2 MBytes 30.3 Mbits/sec 2.302 ms 54/38692 (0.14%)
[ 3] 0.0-15.0 sec 54.1 MBytes 30.2 Mbits/sec 2.227 ms 54/38671 (0.14%)
[ 3] 0.0-15.0 sec 53.5 MBytes 29.9 Mbits/sec 2.043 ms 57/38203 (0.15%)
[ 3] 0.0-15.0 sec 58.1 MBytes 32.5 Mbits/sec 1.843 ms 1/41480 (0.0024%)
<...> ^^^^^^^^^^^^^^^^^
Total throughput is 497.1 Mbits/sec (0.69% higher), average drop rate is
0.08% (99.9% lower).
Fairness between flows is slightly affected, with per-flow average
throughput ranging from 29.9 to 32.6 Mbits/sec (compared with 30.3 to
31.3 Mbits/sec).
Signed-off-by: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
---
net/sched/sch_cbq.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 91a0dc463c48..42e44f570988 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -381,6 +381,7 @@ cbq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
return ret;
}
+ qdisc_backpressure(skb);
if (net_xmit_drop_count(ret)) {
qdisc_qstats_drop(sch);
cbq_mark_toplevel(q, cl);
--
2.20.1
