From b5638d46c90a6998859a4fc9ea697b264da96092 Mon Sep 17 00:00:00 2001 From: Petr Machata Date: Thu, 20 Sep 2018 09:21:36 +0300 Subject: [PATCH] selftests: mlxsw: Add a test for UC behavior under MC flood A so-called "MC-aware" mode has recently been enabled in mlxsw. In MC-aware mode, BUM traffic is handled in a special way so that when a switch is flooded with BUM, UC performance isn't unduly impacted. Without enablement of this mode, a stream of BUM traffic can cause sustained UC throughput drop in excess of 99 %. Add a test for this behavior. Compare how much UC throughput degrades as a stream of broadcast frames floods the switch. A minimal degradation is tolerated to cover for glitches in traffic injection performance. Signed-off-by: Petr Machata Reviewed-by: Jiri Pirko Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller --- .../selftests/drivers/net/mlxsw/qos_mc_aware.sh | 347 +++++++++++++++++++++ 1 file changed, 347 insertions(+) create mode 100644 tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh diff --git a/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh b/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh new file mode 100644 index 0000000..0150bb2 --- /dev/null +++ b/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh @@ -0,0 +1,347 @@ +#!/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 -- 2.7.4