[Patch v4 net 5/6] selftests/tc-testing: Add a test case for mq with netem duplicate

[Cong Wang <xiyou.wangcong@gmail.com>]

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 605a478032d8..b4a507bc48a3 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
@@ -793,5 +793,36 @@
         "teardown": [
             "$TC qdisc del dev $DUMMY root handle 1: prio"
         ]
+    },
+    {
+        "id": "94a8",
+        "name": "Test MQ with NETEM duplication",
+        "category": [
+            "qdisc",
+            "mq",
+            "netem"
+        ],
+        "plugins": {
+            "requires": ["nsPlugin", "scapyPlugin"]
+        },
+        "setup": [
+            "$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