--- /dev/null
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# A test for switch behavior under MC overload. An issue in Spectrum chips
+# causes throughput of UC traffic to drop severely when a switch is under heavy
+# MC load. This issue can be overcome by putting the switch to MC-aware mode.
+# This test verifies that UC performance stays intact even as the switch is
+# under MC flood, and therefore that the MC-aware mode is enabled and correctly
+# configured.
+#
+# Because mlxsw throttles CPU port, the traffic can't actually reach userspace
+# at full speed. That makes it impossible to use iperf3 to simply measure the
+# throughput, because many packets (that reach $h3) don't get to the kernel at
+# all even in UDP mode (the situation is even worse in TCP mode, where one can't
+# hope to see more than a couple Mbps).
+#
+# So instead we send traffic with mausezahn and use RX ethtool counters at $h3.
+# Multicast traffic is untagged, unicast traffic is tagged with PCP 1. Therefore
+# each gets a different priority and we can use per-prio ethtool counters to
+# measure the throughput. In order to avoid prioritizing unicast traffic, prio
+# qdisc is installed on $swp3 and maps all priorities to the same band #7 (and
+# thus TC 0).
+#
+# Mausezahn can't actually saturate the links unless it's using large frames.
+# Thus we set MTU to 10K on all involved interfaces. Then both unicast and
+# multicast traffic uses 8K frames.
+#
+# +-----------------------+ +----------------------------------+
+# | H1 | | H2 |
+# | | | unicast --> + $h2.111 |
+# | | | traffic | 192.0.2.129/28 |
+# | multicast | | | e-qos-map 0:1 |
+# | traffic | | | |
+# | $h1 + <----- | | + $h2 |
+# +-----|-----------------+ +--------------|-------------------+
+# | |
+# +-----|-------------------------------------------------|-------------------+
+# | + $swp1 + $swp2 |
+# | | >1Gbps | >1Gbps |
+# | +---|----------------+ +----------|----------------+ |
+# | | + $swp1.1 | | + $swp2.111 | |
+# | | BR1 | SW | BR111 | |
+# | | + $swp3.1 | | + $swp3.111 | |
+# | +---|----------------+ +----------|----------------+ |
+# | \_________________________________________________/ |
+# | | |
+# | + $swp3 |
+# | | 1Gbps bottleneck |
+# | | prio qdisc: {0..7} -> 7 |
+# +------------------------------------|--------------------------------------+
+# |
+# +--|-----------------+
+# | + $h3 H3 |
+# | | |
+# | + $h3.111 |
+# | 192.0.2.130/28 |
+# +--------------------+
+
+ALL_TESTS="
+ ping_ipv4
+ test_mc_aware
+"
+
+lib_dir=$(dirname $0)/../../../net/forwarding
+
+NUM_NETIFS=6
+source $lib_dir/lib.sh
+
+h1_create()
+{
+ simple_if_init $h1
+ mtu_set $h1 10000
+}
+
+h1_destroy()
+{
+ mtu_restore $h1
+ simple_if_fini $h1
+}
+
+h2_create()
+{
+ simple_if_init $h2
+ mtu_set $h2 10000
+
+ vlan_create $h2 111 v$h2 192.0.2.129/28
+ ip link set dev $h2.111 type vlan egress-qos-map 0:1
+}
+
+h2_destroy()
+{
+ vlan_destroy $h2 111
+
+ mtu_restore $h2
+ simple_if_fini $h2
+}
+
+h3_create()
+{
+ simple_if_init $h3
+ mtu_set $h3 10000
+
+ vlan_create $h3 111 v$h3 192.0.2.130/28
+}
+
+h3_destroy()
+{
+ vlan_destroy $h3 111
+
+ mtu_restore $h3
+ simple_if_fini $h3
+}
+
+switch_create()
+{
+ ip link set dev $swp1 up
+ mtu_set $swp1 10000
+
+ ip link set dev $swp2 up
+ mtu_set $swp2 10000
+
+ ip link set dev $swp3 up
+ mtu_set $swp3 10000
+
+ vlan_create $swp2 111
+ vlan_create $swp3 111
+
+ ethtool -s $swp3 speed 1000 autoneg off
+ tc qdisc replace dev $swp3 root handle 3: \
+ prio bands 8 priomap 7 7 7 7 7 7 7 7
+
+ ip link add name br1 type bridge vlan_filtering 0
+ ip link set dev br1 up
+ ip link set dev $swp1 master br1
+ ip link set dev $swp3 master br1
+
+ ip link add name br111 type bridge vlan_filtering 0
+ ip link set dev br111 up
+ ip link set dev $swp2.111 master br111
+ ip link set dev $swp3.111 master br111
+}
+
+switch_destroy()
+{
+ ip link del dev br111
+ ip link del dev br1
+
+ tc qdisc del dev $swp3 root handle 3:
+ ethtool -s $swp3 autoneg on
+
+ vlan_destroy $swp3 111
+ vlan_destroy $swp2 111
+
+ mtu_restore $swp3
+ ip link set dev $swp3 down
+
+ mtu_restore $swp2
+ ip link set dev $swp2 down
+
+ mtu_restore $swp1
+ ip link set dev $swp1 down
+}
+
+setup_prepare()
+{
+ h1=${NETIFS[p1]}
+ swp1=${NETIFS[p2]}
+
+ swp2=${NETIFS[p3]}
+ h2=${NETIFS[p4]}
+
+ swp3=${NETIFS[p5]}
+ h3=${NETIFS[p6]}
+
+ h3mac=$(mac_get $h3)
+
+ vrf_prepare
+
+ h1_create
+ h2_create
+ h3_create
+ switch_create
+}
+
+cleanup()
+{
+ pre_cleanup
+
+ switch_destroy
+ h3_destroy
+ h2_destroy
+ h1_destroy
+
+ vrf_cleanup
+}
+
+ping_ipv4()
+{
+ ping_test $h2 192.0.2.130
+}
+
+humanize()
+{
+ local speed=$1; shift
+
+ for unit in bps Kbps Mbps Gbps; do
+ if (($(echo "$speed < 1024" | bc))); then
+ break
+ fi
+
+ speed=$(echo "scale=1; $speed / 1024" | bc)
+ done
+
+ echo "$speed${unit}"
+}
+
+rate()
+{
+ local t0=$1; shift
+ local t1=$1; shift
+ local interval=$1; shift
+
+ echo $((8 * (t1 - t0) / interval))
+}
+
+check_rate()
+{
+ local rate=$1; shift
+ local min=$1; shift
+ local what=$1; shift
+
+ if ((rate > min)); then
+ return 0
+ fi
+
+ echo "$what $(humanize $ir) < $(humanize $min_ingress)" > /dev/stderr
+ return 1
+}
+
+measure_uc_rate()
+{
+ local what=$1; shift
+
+ local interval=10
+ local i
+ local ret=0
+
+ # Dips in performance might cause momentary ingress rate to drop below
+ # 1Gbps. That wouldn't saturate egress and MC would thus get through,
+ # seemingly winning bandwidth on account of UC. Demand at least 2Gbps
+ # average ingress rate to somewhat mitigate this.
+ local min_ingress=2147483648
+
+ mausezahn $h2.111 -p 8000 -A 192.0.2.129 -B 192.0.2.130 -c 0 \
+ -a own -b $h3mac -t udp -q &
+ sleep 1
+
+ for i in {5..0}; do
+ local t0=$(ethtool_stats_get $h3 rx_octets_prio_1)
+ local u0=$(ethtool_stats_get $swp2 rx_octets_prio_1)
+ sleep $interval
+ local t1=$(ethtool_stats_get $h3 rx_octets_prio_1)
+ local u1=$(ethtool_stats_get $swp2 rx_octets_prio_1)
+
+ local ir=$(rate $u0 $u1 $interval)
+ local er=$(rate $t0 $t1 $interval)
+
+ if check_rate $ir $min_ingress "$what ingress rate"; then
+ break
+ fi
+
+ # Fail the test if we can't get the throughput.
+ if ((i == 0)); then
+ ret=1
+ fi
+ done
+
+ # Suppress noise from killing mausezahn.
+ { kill %% && wait; } 2>/dev/null
+
+ echo $ir $er
+ exit $ret
+}
+
+test_mc_aware()
+{
+ RET=0
+
+ local -a uc_rate
+ uc_rate=($(measure_uc_rate "UC-only"))
+ check_err $? "Could not get high enough UC-only ingress rate"
+ local ucth1=${uc_rate[1]}
+
+ mausezahn $h1 -p 8000 -c 0 -a own -b bc -t udp -q &
+
+ local d0=$(date +%s)
+ local t0=$(ethtool_stats_get $h3 rx_octets_prio_0)
+ local u0=$(ethtool_stats_get $swp1 rx_octets_prio_0)
+
+ local -a uc_rate_2
+ uc_rate_2=($(measure_uc_rate "UC+MC"))
+ check_err $? "Could not get high enough UC+MC ingress rate"
+ local ucth2=${uc_rate_2[1]}
+
+ local d1=$(date +%s)
+ local t1=$(ethtool_stats_get $h3 rx_octets_prio_0)
+ local u1=$(ethtool_stats_get $swp1 rx_octets_prio_0)
+
+ local deg=$(bc <<< "
+ scale=2
+ ret = 100 * ($ucth1 - $ucth2) / $ucth1
+ if (ret > 0) { ret } else { 0 }
+ ")
+ check_err $(bc <<< "$deg > 10")
+
+ local interval=$((d1 - d0))
+ local mc_ir=$(rate $u0 $u1 $interval)
+ local mc_er=$(rate $t0 $t1 $interval)
+
+ # Suppress noise from killing mausezahn.
+ { kill %% && wait; } 2>/dev/null
+
+ log_test "UC performace under MC overload"
+
+ echo "UC-only throughput $(humanize $ucth1)"
+ echo "UC+MC throughput $(humanize $ucth2)"
+ echo "Degradation $deg %"
+ echo
+ echo "Full report:"
+ echo " UC only:"
+ echo " ingress UC throughput $(humanize ${uc_rate[0]})"
+ echo " egress UC throughput $(humanize ${uc_rate[1]})"
+ echo " UC+MC:"
+ echo " ingress UC throughput $(humanize ${uc_rate_2[0]})"
+ echo " egress UC throughput $(humanize ${uc_rate_2[1]})"
+ echo " ingress MC throughput $(humanize $mc_ir)"
+ echo " egress MC throughput $(humanize $mc_er)"
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS
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