96. Ethernet Link Flow Control Tests¶
The support of Ethernet link flow control features by Poll Mode Drivers consists in:
- At the receive side, if packet buffer is not enough, NIC will send out the pause frame to peer and ask the peer to slow down the Ethernet frame # transmission.
- At the transmit side, if pause frame is received, NIC will slow down the Ethernet frame transmission according to the pause frame.
MAC Control Frame Forwarding consists in:
- Control frames (PAUSE Frames) are taken by the NIC and do not pass to the host.
- When Flow Control and MAC Control Frame Forwarding are enabled the PAUSE frames will be passed to the host and can be handled by testpmd.
Note
Priority flow control is not included in this test plan.
Configuration Functions in testpmd:
Set the link flow control parameter on a port:
testpmd> set flow_ctrl rx (on|off) tx (on|off) (high_water) (low_water) \ (pause_time) (send_xon) mac_ctrl_frame_fwd (on|off) \ autoneg (on|off) (port_id)
high_water(integer): High threshold value to trigger XOFF.low_water(integer): Low threshold value to trigger XON.pause_time(integer): Pause quota in the Pause frame.send_xon(0/1): Send XON frame.mac_ctrl_frame_fwd: Enable receiving MAC control frames.autoneg: Change the auto-negotiation parameter.Note
the high_water, low_water, pause_time, send_xon are configured into the NIC register. It is not necessary to validate the accuracy of these parameters. And what change it can cause. The port_id is used to indicate the NIC to be configured. In certain case, a system can contain multiple NIC. However the NIC need not be configured multiple times.
96.1. Prerequisites¶
Assuming that ports 0 and 2 are connected to a traffic generator,
launch the testpmd with the following arguments:
./build/app/dpdk-testpmd -cffffff -n 3 -- -i --burst=1 --txpt=32 \
--txht=8 --txwt=0 --txfreet=0 --rxfreet=64 --mbcache=250 --portmask=0x5
The -n command is used to select the number of memory channels. It should match the number of memory channels on that setup.
If using vfio the kernel must be >= 3.6+ and VT-d must be enabled in bios.When using vfio, use the following commands to load the vfio driver and bind it to the device under test:
modprobe vfio
modprobe vfio-pci
usertools/dpdk-devbind.py --bind=vfio-pci device_bus_id
96.2. Test Case: Ethernet link flow control¶
This case series are focus on Ethernet link flow control features, requires a high-speed packet generator, such as ixia.
96.2.1. Subcase: test_perf_flowctrl_on_pause_fwd_on¶
Enable both link flow control and PAUSE frame forwarding:
testpmd> set flow_ctrl rx on tx on high_water low_water pause_time
send_xon mac_ctrl_frame_fwd on autoneg on port_id
Setup the csum forwarding mode:
testpmd> set fwd csum
Set csum packet forwarding mode
Start the packet forwarding:
testpmd> start
csum packet forwarding - CRC stripping disabled - packets/burst=32
nb forwarding cores=1 - nb forwarding ports=10
RX queues=1 - RX desc=128 - RX free threshold=64
RX threshold registers: pthresh=8 hthresh=8 wthresh=4
TX queues=1 - TX desc=512 - TX free threshold=0
TX threshold registers: pthresh=32 hthresh=8 wthresh=8
Validate the NIC can generate the pause frame(tx on).
Configure the traffic generator to send IPv4/UDP packet at the length of 66Byte
at the line speed (10G). Because the 66Byte packet cannot reach line rate when
running with testpmd, so it is expected that the pause frame will be sent to the
peer (traffic generator). Ideally this mechanism can avoid the packet loss. And
this depends on high_water/low_water and other parameters are configured properly.
It is strongly recommended that the user look into the data sheet before doing
any flow control configuration. By default, the flow control on 10G is disabled.
the flow control for 1G is enabled.
Validate the NIC can deal with the pause frame(rx on).
Configure the traffic generator to send out large amount of pause frames, this
will cause the NIC to disable / slow down the packet transmission according to
the pause time. Once the traffic generator stop sending the pause frame, the NIC
will restore the packet transmission to the expected rate.
96.2.2. Subcase: test_perf_flowctrl_on_pause_fwd_off¶
Enable link flow control and Disable PAUSE frame forwarding:
testpmd> set flow_ctrl rx on tx on high_water low_water pause_time
send_xon mac_ctrl_frame_fwd off autoneg on port_id
Validate same behavior as test_perf_flowctrl_on_pause_fwd_on
96.2.3. Subcase: test_perf_flowctrl_rx_on¶
Enable only rx link flow control:
testpmd> set flowctrl rx on tx off high_water low_water pause_time
send_xon mac_ctrl_frame_fwd off autoneg on port_id
Validate the NIC can deal with the pause frame(rx on).
96.2.4. Subcase: test_perf_flowctrl_off_pause_fwd_off¶
Disable both link flow control and PAUSE frame forwarding. This is the default mode for 10G PMD, by default, testpmd is running on this mode. no need to execute any command:
testpmd> set flowctrl rx off tx off high_water low_water pause_time
send_xon mac_ctrl_frame_fwd off autoneg on port_id
Validate the NIC won’t generate the pause frame when the packet buffer is not enough. Packet loss can be observed. Validate the NIC will not slow down the packet transmission after receiving the pause frame.
96.2.5. Subcase: test_perf_flowctrl_off_pause_fwd_on¶
Disable link flow control and enable PAUSE frame forwarding:
testpmd> set flowctrl rx off tx off high_water low_water pause_time
send_xon mac_ctrl_frame_fwd on autoneg on port_id
Validate same behavior as test_perf_flowctrl_off_pause_fwd_off
96.2.6. Subcase: test_perf_flowctrl_tx_on¶
Enable only tx link flow control:
testpmd> set flowctrl rx off tx on high_water low_water pause_time
send_xon mac_ctrl_frame_fwd off autoneg on port_id
Validate same behavior as test_perf_flowctrl_on_pause_fwd_off
96.2.7. Subcase: test_perf_flowctrl_on_port_stop_start¶
Link flow control setting still working after port stop/start.
enableLink flow control:testpmd> set flow_ctrl rx on tx on high_water low_water pause_time send_xon mac_ctrl_frame_fwd off autoneg on port_id
validate behavior same as
test_perf_flowctrl_on_pause_fwd_off.Stop and start port:
testpmd> stop testpmd> port stop 0 testpmd> port start 0 testpmd> start
validate behavior same as
test_perf_flowctrl_on_pause_fwd_off.disableLink flow control:testpmd> set flowctrl rx off tx off high_water low_water pause_time send_xon mac_ctrl_frame_fwd off autoneg on port_id
validate behavior same as
test_perf_flowctrl_off_pause_fwd_off.Stop and start port:
testpmd> stop testpmd> port stop 0 testpmd> port start 0 testpmd> start
validate behavior same as
test_perf_flowctrl_off_pause_fwd_off.
96.3. Test Case: MAC Control Frame Forwarding¶
This case series foucs on MAC Control Frame Forwarding, no requirment of
high-speed packets, it’s very friendship to use scapy as packet generator.
96.3.1. Subcase: test_flowctrl_off_pause_fwd_off¶
PAUSE Frames will not be received by testpmd while Flow Control disabled and MAC Control Frame Forwarding disabled:
testpmd> set flow_ctrl rx off tx off 300 50 10 1 mac_ctrl_frame_fwd off autoneg off 0
Send PAUSE packets to DUT with below options:
- Regular frame (correct src and dst mac addresses and opcode)
- Wrong source frame (wrong src, correct and dst mac address and correct opcode)
- Wrong opcode frame (correct src and dst mac address and wrong opcode)
- Wrong destination frame (correct src mac and opcode, wrong dst mac address)
Validate no packet received by testpmd according to show port stats all
96.3.2. Subcase: test_flowctrl_off_pause_fwd_on¶
All PAUSE Frames will be forwarded by testpmd while Flow Control disabled and MAC Control Frame Forwarding enabled:
testpmd> set flow_ctrl rx off tx off 300 50 10 1 mac_ctrl_frame_fwd on autoneg off 0
Send PAUSE packets to DUT with same options as test_flowctrl_off_pause_fwd_off
Validate port statistic match below table
| # | Frames | Received |
|---|---|---|
| 0 | Regular frame | Yes |
| 1 | Wrong src mac | Yes |
| 2 | Wrong opcode | Yes |
| 3 | Wrong dst mac | Yes |
96.3.3. Subcase: test_pause_fwd_port_stop_start¶
MAC Control Frame Forwarding setting still working after port stop/start.
enableMAC Control Frame Forwarding, and validate packets are received:testpmd> set flow_ctrl mac_ctrl_frame_fwd on 0
Send regular PAUSE packets to DUT, and validate packets are received.
Stop and start port:
testpmd> stop testpmd> port stop 0 testpmd> port start 0 testpmd> start
Send regular PAUSE packets to DUT, and validate packets are received.
disableMAC Control Frame Forwarding, and validatenopackets are received:testpmd> set flow_ctrl mac_ctrl_frame_fwd off 0
Send regular PAUSE packets to DUT, and validate
nopackets are received.Stop and start port:
testpmd> stop testpmd> port stop 0 testpmd> port start 0 testpmd> start
Send regular PAUSE packets to DUT, and validate
nopackets are received.