[PATCH RFC v2 net-next 4/5] net/sched: sch_htb: Use Qdisc backpressure infrastructure
From: Peilin Ye <hidden>
Date: 2022-08-22 09:14:01
Also in:
linux-doc, lkml
Subsystem:
networking [general], tc subsystem, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
From: Peilin Ye <redacted> Recently we introduced a Qdisc backpressure infrastructure (currently supports UDP sockets). Use it in HTB Qdisc. Tested with 500 Mbits/sec rate limit using 16 iperf UDP 1 Gbit/sec clients. Before: [ 3] 0.0-15.0 sec 54.2 MBytes 30.4 Mbits/sec 0.875 ms 1245750/1284444 (97%) [ 3] 0.0-15.0 sec 54.2 MBytes 30.3 Mbits/sec 1.288 ms 1238753/1277402 (97%) [ 3] 0.0-15.0 sec 54.8 MBytes 30.6 Mbits/sec 1.761 ms 1261762/1300817 (97%) [ 3] 0.0-15.0 sec 53.9 MBytes 30.1 Mbits/sec 1.635 ms 1241690/1280133 (97%) <...> ^^^^^^^^^^^^^^^^^^^^^ Total throughput is 482.0 Mbits/sec and average drop rate is 97.0%. Now enable Qdisc backpressure for UDP sockets, with udp_backpressure_interval default to 100 milliseconds: [ 3] 0.0-15.0 sec 53.0 MBytes 29.6 Mbits/sec 1.621 ms 54/37856 (0.14%) [ 3] 0.0-15.0 sec 55.9 MBytes 31.3 Mbits/sec 1.368 ms 6/39895 (0.015%) [ 3] 0.0-15.0 sec 52.3 MBytes 29.2 Mbits/sec 1.560 ms 56/37340 (0.15%) [ 3] 0.0-15.0 sec 52.7 MBytes 29.5 Mbits/sec 1.495 ms 57/37677 (0.15%) <...> ^^^^^^^^^^^^^^^^ Total throughput is 485.9 Mbits/sec (0.81% higher) and average drop rate is 0.1% (99.9% lower). Fairness between flows is slightly affected, with per-flow average throughput ranging from 29.2 to 31.8 Mbits/sec (compared with 29.7 to 30.6 Mbits/sec). Signed-off-by: Peilin Ye <redacted> --- net/sched/sch_htb.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 23a9d6242429..e337b3d0dab3 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c@@ -623,6 +623,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch, __qdisc_enqueue_tail(skb, &q->direct_queue); q->direct_pkts++; } else { + qdisc_backpressure(skb); return qdisc_drop(skb, sch, to_free); } #ifdef CONFIG_NET_CLS_ACT
@@ -634,6 +635,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch, #endif } else if ((ret = qdisc_enqueue(skb, cl->leaf.q, to_free)) != NET_XMIT_SUCCESS) { + qdisc_backpressure(skb); if (net_xmit_drop_count(ret)) { qdisc_qstats_drop(sch); cl->drops++;
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2.20.1