[Patch net v6 7/8] selftests/tc-testing: Add a test case for mq with netem duplicate

Cong Wang
2025-12-27T19:41:55Z

Given that multi-queue NICs are prevalent and the global spinlock issue with
single netem instances is a known performance limitation, the setup using
mq as a parent for netem is an excellent and highly reasonable pattern for
applying netem effects like 100% duplication efficiently on modern Linux
systems.

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
.../tc-testing/tc-tests/infra/qdiscs.json | 31 +++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
index b65fe669e00a..57e6b5f35070 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
@@ -1141,5 +1141,36 @@
"teardown": [
"$TC qdisc del dev $DUMMY root handle 1:"
]
+ },
+ {
+ "id": "94a8",
+ "name": "Test MQ with NETEM duplication",
+ "category": [
+ "qdisc",
+ "mq",
+ "netem"
+ ],
+ "plugins": {
+ "requires": ["nsPlugin", "scapyPlugin"]
+ },
+ "setup": [
+ "$IP link set dev $DEV1 up",
+ "$TC qdisc add dev $DEV1 root handle 1: mq",
+ "$TC qdisc add dev $DEV1 parent 1:1 handle 10: netem duplicate 100%",
+ "$TC qdisc add dev $DEV1 parent 1:2 handle 20: netem duplicate 100%"
+ ],
+ "scapy": {
+ "iface": "$DEV0",
+ "count": 5,
+ "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()"
+ },
+ "cmdUnderTest": "$TC -s qdisc show dev $DEV1",
+ "expExitCode": "0",
+ "verifyCmd": "$TC -s qdisc show dev $DEV1 | grep -A 5 'qdisc netem' | grep -E 'Sent [0-9]+ bytes [0-9]+ pkt'",
+ "matchPattern": "Sent \\d+ bytes (\\d+) pkt",
+ "matchCount": "2",
+ "teardown": [
+ "$TC qdisc del dev $DEV1 root handle 1: mq"
+ ]
}
]
--
2.34.1