selftests: mlxsw: Add a test for soaking up a burst of traffic

Add a test that sends 1Gbps of traffic through the switch, into which it
then injects a burst of traffic and tests that there are no drops.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/drivers/net/mlxsw/qos_burst.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# This test sends 1Gbps of traffic through the switch, into which it then
+# injects a burst of traffic and tests that there are no drops.
+#
+# The 1Gbps stream is created by sending >1Gbps stream from H1. This stream
+# ingresses through $swp1, and is forwarded thtrough a small temporary pool to a
+# 1Gbps $swp3.
+#
+# Thus a 1Gbps stream enters $swp4, and is forwarded through a large pool to
+# $swp2, and eventually to H2. Since $swp2 is a 1Gbps port as well, no backlog
+# is generated.
+#
+# At this point, a burst of traffic is forwarded from H3. This enters $swp5, is
+# forwarded to $swp2, which is fully subscribed by the 1Gbps stream. The
+# expectation is that the burst is wholly absorbed by the large pool and no
+# drops are caused. After the burst, there should be a backlog that is hard to
+# get rid of, because $sw2 is fully subscribed. But because each individual
+# packet is scheduled soon after getting enqueued, SLL and HLL do not impact the
+# test.
+#
+# +-----------------------+                           +-----------------------+
+# | H1                    |			      | H3                    |
+# |   + $h1.111           |			      |          $h3.111 +    |
+# |   | 192.0.2.33/28     |			      |    192.0.2.35/28 |    |
+# |   |                   |			      |                  |    |
+# |   + $h1               |			      |              $h3 +    |
+# +---|-------------------+  +--------------------+   +------------------|----+
+#     |                      |                    |       		 |
+# +---|----------------------|--------------------|----------------------|----+
+# |   + $swp1          $swp3 +                    + $swp4          $swp5 |    |
+# |   | iPOOL1        iPOOL0 |                    | iPOOL2        iPOOL2 |    |
+# |   | ePOOL4        ePOOL5 |                    | ePOOL4        ePOOL4 |    |
+# |   |                1Gbps |                    | 1Gbps                |    |
+# | +-|----------------------|-+                +-|----------------------|-+  |
+# | | + $swp1.111  $swp3.111 + |                | + $swp4.111  $swp5.111 + |  |
+# | |                          |                |                          |  |
+# | | BR1                      |                | BR2                      |  |
+# | |                          |                |                          |  |
+# | |                          |                |         + $swp2.111      |  |
+# | +--------------------------+                +---------|----------------+  |
+# |                                                       |                   |
+# | iPOOL0: 500KB dynamic                                 |                   |
+# | iPOOL1: 500KB dynamic                                 |                   |
+# | iPOOL2: 10MB dynamic                                  + $swp2             |
+# | ePOOL4: 500KB dynamic                                 | iPOOL0            |
+# | ePOOL5: 500KB dnamic                                  | ePOOL6            |
+# | ePOOL6: 10MB dynamic                                  | 1Gbps             |
+# +-------------------------------------------------------|-------------------+
+#                                                         |
+#                                                     +---|-------------------+
+#                                                     |   + $h2            H2 |
+#                                                     |   | 1Gbps             |
+#                                                     |   |                   |
+#                                                     |   + $h2.111           |
+#                                                     |     192.0.2.34/28     |
+#                                                     +-----------------------+
+#
+# iPOOL0+ePOOL4 are helper pools for control traffic etc.
+# iPOOL1+ePOOL5 are helper pools for modeling the 1Gbps stream
+# iPOOL2+ePOOL6 are pools for soaking the burst traffic
+
+ALL_TESTS="
+	ping_ipv4
+	test_8K
+	test_800
+"
+
+lib_dir=$(dirname $0)/../../../net/forwarding
+
+NUM_NETIFS=8
+source $lib_dir/lib.sh
+source $lib_dir/devlink_lib.sh
+source qos_lib.sh
+source mlxsw_lib.sh
+
+_1KB=1000
+_500KB=$((500 * _1KB))
+_1MB=$((1000 * _1KB))
+
+# The failure mode that this specifically tests is exhaustion of descriptor
+# buffer. The point is to produce a burst that shared buffer should be able
+# to accommodate, but produce it with small enough packets that the machine
+# runs out of the descriptor buffer space with default configuration.
+#
+# The machine therefore needs to be able to produce line rate with as small
+# packets as possible, and at the same time have large enough buffer that
+# when filled with these small packets, it runs out of descriptors.
+# Spectrum-2 is very close, but cannot perform this test. Therefore use
+# Spectrum-3 as a minimum, and permit larger burst size, and therefore
+# larger packets, to reduce spurious failures.
+#
+mlxsw_only_on_spectrum 3+ || exit
+
+BURST_SIZE=$((50000000))
+POOL_SIZE=$BURST_SIZE
+
+h1_create()
+{
+	simple_if_init $h1
+	mtu_set $h1 10000
+
+	vlan_create $h1 111 v$h1 192.0.2.33/28
+	ip link set dev $h1.111 type vlan egress-qos-map 0:1
+}
+
+h1_destroy()
+{
+	vlan_destroy $h1 111
+
+	mtu_restore $h1
+	simple_if_fini $h1
+}
+
+h2_create()
+{
+	simple_if_init $h2
+	mtu_set $h2 10000
+	ethtool -s $h2 speed 1000 autoneg off
+
+	vlan_create $h2 111 v$h2 192.0.2.34/28
+}
+
+h2_destroy()
+{
+	vlan_destroy $h2 111
+
+	ethtool -s $h2 autoneg on
+	mtu_restore $h2
+	simple_if_fini $h2
+}
+
+h3_create()
+{
+	simple_if_init $h3
+	mtu_set $h3 10000
+
+	vlan_create $h3 111 v$h3 192.0.2.35/28
+}
+
+h3_destroy()
+{
+	vlan_destroy $h3 111
+
+	mtu_restore $h3
+	simple_if_fini $h3
+}
+
+switch_create()
+{
+	# pools
+	# -----
+
+	devlink_pool_size_thtype_save 0
+	devlink_pool_size_thtype_save 4
+	devlink_pool_size_thtype_save 1
+	devlink_pool_size_thtype_save 5
+	devlink_pool_size_thtype_save 2
+	devlink_pool_size_thtype_save 6
+
+	devlink_port_pool_th_save $swp1 1
+	devlink_port_pool_th_save $swp2 6
+	devlink_port_pool_th_save $swp3 5
+	devlink_port_pool_th_save $swp4 2
+	devlink_port_pool_th_save $swp5 2
+
+	devlink_tc_bind_pool_th_save $swp1 1 ingress
+	devlink_tc_bind_pool_th_save $swp2 1 egress
+	devlink_tc_bind_pool_th_save $swp3 1 egress
+	devlink_tc_bind_pool_th_save $swp4 1 ingress
+	devlink_tc_bind_pool_th_save $swp5 1 ingress
+
+	# Control traffic pools. Just reduce the size.
+	devlink_pool_size_thtype_set 0 dynamic $_500KB
+	devlink_pool_size_thtype_set 4 dynamic $_500KB
+
+	# Stream modeling pools.
+	devlink_pool_size_thtype_set 1 dynamic $_500KB
+	devlink_pool_size_thtype_set 5 dynamic $_500KB
+
+	# Burst soak pools.
+	devlink_pool_size_thtype_set 2 static $POOL_SIZE
+	devlink_pool_size_thtype_set 6 static $POOL_SIZE
+
+	# $swp1
+	# -----
+
+	ip link set dev $swp1 up
+	mtu_set $swp1 10000
+	vlan_create $swp1 111
+	ip link set dev $swp1.111 type vlan ingress-qos-map 0:0 1:1
+
+	devlink_port_pool_th_set $swp1 1 16
+	devlink_tc_bind_pool_th_set $swp1 1 ingress 1 16
+
+	# Configure qdisc...
+	tc qdisc replace dev $swp1 root handle 1: \
+	   ets bands 8 strict 8 priomap 7 6
+	# ... so that we can assign prio1 traffic to PG1.
+	dcb buffer set dev $swp1 prio-buffer all:0 1:1
+
+	# $swp2
+	# -----
+
+	ip link set dev $swp2 up
+	mtu_set $swp2 10000
+	ethtool -s $swp2 speed 1000 autoneg off
+	vlan_create $swp2 111
+	ip link set dev $swp2.111 type vlan egress-qos-map 0:0 1:1
+
+	devlink_port_pool_th_set $swp2 6 $POOL_SIZE
+	devlink_tc_bind_pool_th_set $swp2 1 egress 6 $POOL_SIZE
+
+	# prio 0->TC0 (band 7), 1->TC1 (band 6)
+	tc qdisc replace dev $swp2 root handle 1: \
+	   ets bands 8 strict 8 priomap 7 6
+
+	# $swp3
+	# -----
+
+	ip link set dev $swp3 up
+	mtu_set $swp3 10000
+	ethtool -s $swp3 speed 1000 autoneg off
+	vlan_create $swp3 111
+	ip link set dev $swp3.111 type vlan egress-qos-map 0:0 1:1
+
+	devlink_port_pool_th_set $swp3 5 16
+	devlink_tc_bind_pool_th_set $swp3 1 egress 5 16
+
+	# prio 0->TC0 (band 7), 1->TC1 (band 6)
+	tc qdisc replace dev $swp3 root handle 1: \
+	   ets bands 8 strict 8 priomap 7 6
+
+	# $swp4
+	# -----
+
+	ip link set dev $swp4 up
+	mtu_set $swp4 10000
+	ethtool -s $swp4 speed 1000 autoneg off
+	vlan_create $swp4 111
+	ip link set dev $swp4.111 type vlan ingress-qos-map 0:0 1:1
+
+	devlink_port_pool_th_set $swp4 2 $POOL_SIZE
+	devlink_tc_bind_pool_th_set $swp4 1 ingress 2 $POOL_SIZE
+
+	# Configure qdisc...
+	tc qdisc replace dev $swp4 root handle 1: \
+	   ets bands 8 strict 8 priomap 7 6
+	# ... so that we can assign prio1 traffic to PG1.
+	dcb buffer set dev $swp4 prio-buffer all:0 1:1
+
+	# $swp5
+	# -----
+
+	ip link set dev $swp5 up
+	mtu_set $swp5 10000
+	vlan_create $swp5 111
+	ip link set dev $swp5.111 type vlan ingress-qos-map 0:0 1:1
+
+	devlink_port_pool_th_set $swp5 2 $POOL_SIZE
+	devlink_tc_bind_pool_th_set $swp5 1 ingress 2 $POOL_SIZE
+
+	# Configure qdisc...
+	tc qdisc replace dev $swp5 root handle 1: \
+	   ets bands 8 strict 8 priomap 7 6
+	# ... so that we can assign prio1 traffic to PG1.
+	dcb buffer set dev $swp5 prio-buffer all:0 1:1
+
+	# bridges
+	# -------
+
+	ip link add name br1 type bridge vlan_filtering 0
+	ip link set dev $swp1.111 master br1
+	ip link set dev $swp3.111 master br1
+	ip link set dev br1 up
+
+	ip link add name br2 type bridge vlan_filtering 0
+	ip link set dev $swp2.111 master br2
+	ip link set dev $swp4.111 master br2
+	ip link set dev $swp5.111 master br2
+	ip link set dev br2 up
+}
+
+switch_destroy()
+{
+	# Do this first so that we can reset the limits to values that are only
+	# valid for the original static / dynamic setting.
+	devlink_pool_size_thtype_restore 6
+	devlink_pool_size_thtype_restore 5
+	devlink_pool_size_thtype_restore 4
+	devlink_pool_size_thtype_restore 2
+	devlink_pool_size_thtype_restore 1
+	devlink_pool_size_thtype_restore 0
+
+	# bridges
+	# -------
+
+	ip link set dev br2 down
+	ip link set dev $swp5.111 nomaster
+	ip link set dev $swp4.111 nomaster
+	ip link set dev $swp2.111 nomaster
+	ip link del dev br2
+
+	ip link set dev br1 down
+	ip link set dev $swp3.111 nomaster
+	ip link set dev $swp1.111 nomaster
+	ip link del dev br1
+
+	# $swp5
+	# -----
+
+	dcb buffer set dev $swp5 prio-buffer all:0
+	tc qdisc del dev $swp5 root
+
+	devlink_tc_bind_pool_th_restore $swp5 1 ingress
+	devlink_port_pool_th_restore $swp5 2
+
+	vlan_destroy $swp5 111
+	mtu_restore $swp5
+	ip link set dev $swp5 down
+
+	# $swp4
+	# -----
+
+	dcb buffer set dev $swp4 prio-buffer all:0
+	tc qdisc del dev $swp4 root
+
+	devlink_tc_bind_pool_th_restore $swp4 1 ingress
+	devlink_port_pool_th_restore $swp4 2
+
+	vlan_destroy $swp4 111
+	ethtool -s $swp4 autoneg on
+	mtu_restore $swp4
+	ip link set dev $swp4 down
+
+	# $swp3
+	# -----
+
+	tc qdisc del dev $swp3 root
+
+	devlink_tc_bind_pool_th_restore $swp3 1 egress
+	devlink_port_pool_th_restore $swp3 5
+
+	vlan_destroy $swp3 111
+	ethtool -s $swp3 autoneg on
+	mtu_restore $swp3
+	ip link set dev $swp3 down
+
+	# $swp2
+	# -----
+
+	tc qdisc del dev $swp2 root
+
+	devlink_tc_bind_pool_th_restore $swp2 1 egress
+	devlink_port_pool_th_restore $swp2 6
+
+	vlan_destroy $swp2 111
+	ethtool -s $swp2 autoneg on
+	mtu_restore $swp2
+	ip link set dev $swp2 down
+
+	# $swp1
+	# -----
+
+	dcb buffer set dev $swp1 prio-buffer all:0
+	tc qdisc del dev $swp1 root
+
+	devlink_tc_bind_pool_th_restore $swp1 1 ingress
+	devlink_port_pool_th_restore $swp1 1
+
+	vlan_destroy $swp1 111
+	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]}
+	swp4=${NETIFS[p6]}
+
+	swp5=${NETIFS[p7]}
+	h3=${NETIFS[p8]}
+
+	h2mac=$(mac_get $h2)
+
+	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 $h1 192.0.2.34 " h1->h2"
+	ping_test $h3 192.0.2.34 " h3->h2"
+}
+
+__test_qos_burst()
+{
+	local pktsize=$1; shift
+
+	RET=0
+
+	start_traffic_pktsize $pktsize $h1.111 192.0.2.33 192.0.2.34 $h2mac
+	sleep 1
+
+	local q0=$(ethtool_stats_get $swp2 tc_transmit_queue_tc_1)
+	((q0 == 0))
+	check_err $? "Transmit queue non-zero?"
+
+	local d0=$(ethtool_stats_get $swp2 tc_no_buffer_discard_uc_tc_1)
+
+	local cell_size=$(devlink_cell_size_get)
+	local cells=$((BURST_SIZE / cell_size))
+	# Each packet is $pktsize of payload + headers.
+	local pkt_cells=$(((pktsize + 50 + cell_size - 1)  / cell_size))
+	# How many packets can we admit:
+	local pkts=$((cells / pkt_cells))
+
+	$MZ $h3 -p $pktsize -Q 1:111 -A 192.0.2.35 -B 192.0.2.34 \
+		-a own -b $h2mac -c $pkts -t udp -q
+	sleep 1
+
+	local d1=$(ethtool_stats_get $swp2 tc_no_buffer_discard_uc_tc_1)
+	((d1 == d0))
+	check_err $? "Drops seen on egress port: $d0 -> $d1 ($((d1 - d0)))"
+
+	# Check that the queue is somewhat close to the burst size This
+	# makes sure that the lack of drops above was not due to port
+	# undersubscribtion.
+	local q0=$(ethtool_stats_get $swp2 tc_transmit_queue_tc_1)
+	local qe=$((90 * BURST_SIZE / 100))
+	((q0 > qe))
+	check_err $? "Queue size expected >$qe, got $q0"
+
+	stop_traffic
+	sleep 2
+
+	log_test "Burst: absorb $pkts ${pktsize}-B packets"
+}
+
+test_8K()
+{
+	__test_qos_burst 8000
+}
+
+test_800()
+{
+	__test_qos_burst 800
+}
+
+bail_on_lldpad
+
+trap cleanup EXIT
+setup_prepare
+setup_wait
+tests_run
+
+exit $EXIT_STATUS