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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 <petrm@mellanox.com> Reviewed-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: Ido Schimmel <idosch@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Petr Machata
David S. Miller
parent
a381ed12ea
commit
b5638d46c9
1 changed files with 347 additions and 0 deletions
347
tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh
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347
tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh
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#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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#
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# A test for switch behavior under MC overload. An issue in Spectrum chips
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# causes throughput of UC traffic to drop severely when a switch is under heavy
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# MC load. This issue can be overcome by putting the switch to MC-aware mode.
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# This test verifies that UC performance stays intact even as the switch is
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# under MC flood, and therefore that the MC-aware mode is enabled and correctly
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# configured.
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#
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# Because mlxsw throttles CPU port, the traffic can't actually reach userspace
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# at full speed. That makes it impossible to use iperf3 to simply measure the
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# throughput, because many packets (that reach $h3) don't get to the kernel at
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# all even in UDP mode (the situation is even worse in TCP mode, where one can't
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# hope to see more than a couple Mbps).
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#
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# So instead we send traffic with mausezahn and use RX ethtool counters at $h3.
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# Multicast traffic is untagged, unicast traffic is tagged with PCP 1. Therefore
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# each gets a different priority and we can use per-prio ethtool counters to
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# measure the throughput. In order to avoid prioritizing unicast traffic, prio
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# qdisc is installed on $swp3 and maps all priorities to the same band #7 (and
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# thus TC 0).
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#
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# Mausezahn can't actually saturate the links unless it's using large frames.
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# Thus we set MTU to 10K on all involved interfaces. Then both unicast and
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# multicast traffic uses 8K frames.
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#
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# +-----------------------+ +----------------------------------+
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# | H1 | | H2 |
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# | | | unicast --> + $h2.111 |
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# | | | traffic | 192.0.2.129/28 |
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# | multicast | | | e-qos-map 0:1 |
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# | traffic | | | |
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# | $h1 + <----- | | + $h2 |
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# +-----|-----------------+ +--------------|-------------------+
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# | |
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# +-----|-------------------------------------------------|-------------------+
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# | + $swp1 + $swp2 |
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# | | >1Gbps | >1Gbps |
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# | +---|----------------+ +----------|----------------+ |
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# | | + $swp1.1 | | + $swp2.111 | |
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# | | BR1 | SW | BR111 | |
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# | | + $swp3.1 | | + $swp3.111 | |
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# | +---|----------------+ +----------|----------------+ |
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# | \_________________________________________________/ |
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# | | |
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# | + $swp3 |
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# | | 1Gbps bottleneck |
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# | | prio qdisc: {0..7} -> 7 |
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# +------------------------------------|--------------------------------------+
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# |
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# +--|-----------------+
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# | + $h3 H3 |
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# | | |
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# | + $h3.111 |
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# | 192.0.2.130/28 |
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# +--------------------+
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ALL_TESTS="
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ping_ipv4
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test_mc_aware
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"
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lib_dir=$(dirname $0)/../../../net/forwarding
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NUM_NETIFS=6
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source $lib_dir/lib.sh
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h1_create()
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{
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simple_if_init $h1
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mtu_set $h1 10000
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}
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h1_destroy()
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{
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mtu_restore $h1
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simple_if_fini $h1
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}
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h2_create()
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{
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simple_if_init $h2
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mtu_set $h2 10000
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vlan_create $h2 111 v$h2 192.0.2.129/28
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ip link set dev $h2.111 type vlan egress-qos-map 0:1
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}
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h2_destroy()
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{
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vlan_destroy $h2 111
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mtu_restore $h2
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simple_if_fini $h2
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}
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h3_create()
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{
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simple_if_init $h3
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mtu_set $h3 10000
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vlan_create $h3 111 v$h3 192.0.2.130/28
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}
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h3_destroy()
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{
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vlan_destroy $h3 111
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mtu_restore $h3
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simple_if_fini $h3
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}
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switch_create()
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{
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ip link set dev $swp1 up
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mtu_set $swp1 10000
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ip link set dev $swp2 up
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mtu_set $swp2 10000
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ip link set dev $swp3 up
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mtu_set $swp3 10000
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vlan_create $swp2 111
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vlan_create $swp3 111
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ethtool -s $swp3 speed 1000 autoneg off
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tc qdisc replace dev $swp3 root handle 3: \
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prio bands 8 priomap 7 7 7 7 7 7 7 7
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ip link add name br1 type bridge vlan_filtering 0
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ip link set dev br1 up
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ip link set dev $swp1 master br1
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ip link set dev $swp3 master br1
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ip link add name br111 type bridge vlan_filtering 0
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ip link set dev br111 up
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ip link set dev $swp2.111 master br111
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ip link set dev $swp3.111 master br111
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}
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switch_destroy()
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{
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ip link del dev br111
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ip link del dev br1
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tc qdisc del dev $swp3 root handle 3:
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ethtool -s $swp3 autoneg on
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vlan_destroy $swp3 111
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vlan_destroy $swp2 111
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mtu_restore $swp3
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ip link set dev $swp3 down
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mtu_restore $swp2
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ip link set dev $swp2 down
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mtu_restore $swp1
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ip link set dev $swp1 down
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}
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setup_prepare()
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{
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h1=${NETIFS[p1]}
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swp1=${NETIFS[p2]}
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swp2=${NETIFS[p3]}
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h2=${NETIFS[p4]}
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swp3=${NETIFS[p5]}
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h3=${NETIFS[p6]}
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h3mac=$(mac_get $h3)
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vrf_prepare
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h1_create
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h2_create
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h3_create
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switch_create
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}
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cleanup()
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{
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pre_cleanup
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switch_destroy
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h3_destroy
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h2_destroy
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h1_destroy
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vrf_cleanup
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}
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ping_ipv4()
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{
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ping_test $h2 192.0.2.130
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}
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humanize()
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{
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local speed=$1; shift
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for unit in bps Kbps Mbps Gbps; do
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if (($(echo "$speed < 1024" | bc))); then
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break
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fi
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speed=$(echo "scale=1; $speed / 1024" | bc)
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done
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echo "$speed${unit}"
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}
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rate()
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{
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local t0=$1; shift
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local t1=$1; shift
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local interval=$1; shift
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echo $((8 * (t1 - t0) / interval))
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}
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check_rate()
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{
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local rate=$1; shift
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local min=$1; shift
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local what=$1; shift
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if ((rate > min)); then
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return 0
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fi
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echo "$what $(humanize $ir) < $(humanize $min_ingress)" > /dev/stderr
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return 1
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}
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measure_uc_rate()
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{
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local what=$1; shift
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local interval=10
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local i
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local ret=0
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# Dips in performance might cause momentary ingress rate to drop below
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# 1Gbps. That wouldn't saturate egress and MC would thus get through,
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# seemingly winning bandwidth on account of UC. Demand at least 2Gbps
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# average ingress rate to somewhat mitigate this.
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local min_ingress=2147483648
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mausezahn $h2.111 -p 8000 -A 192.0.2.129 -B 192.0.2.130 -c 0 \
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-a own -b $h3mac -t udp -q &
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sleep 1
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for i in {5..0}; do
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local t0=$(ethtool_stats_get $h3 rx_octets_prio_1)
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local u0=$(ethtool_stats_get $swp2 rx_octets_prio_1)
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sleep $interval
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local t1=$(ethtool_stats_get $h3 rx_octets_prio_1)
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local u1=$(ethtool_stats_get $swp2 rx_octets_prio_1)
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local ir=$(rate $u0 $u1 $interval)
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local er=$(rate $t0 $t1 $interval)
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if check_rate $ir $min_ingress "$what ingress rate"; then
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break
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fi
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# Fail the test if we can't get the throughput.
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if ((i == 0)); then
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ret=1
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fi
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done
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# Suppress noise from killing mausezahn.
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{ kill %% && wait; } 2>/dev/null
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echo $ir $er
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exit $ret
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}
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test_mc_aware()
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{
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RET=0
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local -a uc_rate
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uc_rate=($(measure_uc_rate "UC-only"))
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check_err $? "Could not get high enough UC-only ingress rate"
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local ucth1=${uc_rate[1]}
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mausezahn $h1 -p 8000 -c 0 -a own -b bc -t udp -q &
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local d0=$(date +%s)
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local t0=$(ethtool_stats_get $h3 rx_octets_prio_0)
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local u0=$(ethtool_stats_get $swp1 rx_octets_prio_0)
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local -a uc_rate_2
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uc_rate_2=($(measure_uc_rate "UC+MC"))
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check_err $? "Could not get high enough UC+MC ingress rate"
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local ucth2=${uc_rate_2[1]}
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local d1=$(date +%s)
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local t1=$(ethtool_stats_get $h3 rx_octets_prio_0)
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local u1=$(ethtool_stats_get $swp1 rx_octets_prio_0)
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local deg=$(bc <<< "
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scale=2
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ret = 100 * ($ucth1 - $ucth2) / $ucth1
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if (ret > 0) { ret } else { 0 }
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")
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check_err $(bc <<< "$deg > 10")
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local interval=$((d1 - d0))
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local mc_ir=$(rate $u0 $u1 $interval)
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local mc_er=$(rate $t0 $t1 $interval)
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# Suppress noise from killing mausezahn.
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{ kill %% && wait; } 2>/dev/null
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log_test "UC performace under MC overload"
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echo "UC-only throughput $(humanize $ucth1)"
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echo "UC+MC throughput $(humanize $ucth2)"
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echo "Degradation $deg %"
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echo
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echo "Full report:"
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echo " UC only:"
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echo " ingress UC throughput $(humanize ${uc_rate[0]})"
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echo " egress UC throughput $(humanize ${uc_rate[1]})"
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echo " UC+MC:"
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echo " ingress UC throughput $(humanize ${uc_rate_2[0]})"
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echo " egress UC throughput $(humanize ${uc_rate_2[1]})"
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echo " ingress MC throughput $(humanize $mc_ir)"
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echo " egress MC throughput $(humanize $mc_er)"
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}
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trap cleanup EXIT
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setup_prepare
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setup_wait
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tests_run
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exit $EXIT_STATUS
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