testpmd 应用可以用于以包转发模式（packet forwarding mode）测试 DPDK，也可以访问具有如 Flow Director 特性的硬件网卡。它也被用作说明如何使用 DPDK SDK构建更多功能的应用程序。
testpmd 支持的转发模式
testpmd> set fwd (io|mac|macswap|flowgen| \
rxonly|txonly|csum|icmpecho|noisy|5tswap|shared-rxq) (""|retry)
转发模式说明：
io：按 原始I/O 方式转发报文。这是最快的转发操作，因为它不访问数据包数据。这是默认模式mac：在转发报文之前改变报文的源以太网地址和目的以太网地址。应用程序的默认行为是将源以太网地址设置为发送接口的地址，将目的地址设置为一个虚拟值(在init时设置)。用户可以通过命令行选项 eth-peer 或 eth-peers-configfile 指定目标目的以太网地址。目前还不能指定特定的源以太网地址macswap：MAC交换转发模式。在转发数据包之前，交换数据包的源和目的以太网地址flowgen：多流生成方式。发起大量流(具有不同的目的IP地址)，并终止接收流量rxonly：接收报文但不发送txonly：不接收报文，生成并发送报文csum：根据数据包上的卸载标志用硬件或软件方法改变校验和字段icmpecho：接收大量报文，查找ICMP echo请求，如果有，返回ICMP echo应答ieee1588：演示 L2 IEEE1588 V2 点对 RX 和 TX 的时间戳noisy：吵闹的邻居模拟。模拟执行虚拟网络功能(VNF)的接收和发送数据包的客户机器的更真实的行为5tswap：Swap the source and destination of L2,L3,L4 if they exist.shared-rxq：只接收共享的Rx队列。从mbuf解析数据包的源端口，并相应地更新流统计信息
参考：http://doc.dpdk.org/guides/testpmd_app_ug/testpmd_funcs.html#set-fwd
编译
执行 /usertools/dpdk-setup.sh 选择 [58] Run testpmd application in interactive mode ($RTE_TARGET/app/testpmd)：
$ export RTE_SDK=/root/dpdk-stable-19.11.7/
$ export RTE_TARGET=x86_64-native-linux-gcc
$ ./usertools/dpdk-setup.sh
...
----------------------------------------------------------
Step 3: Run test application for linux environment
----------------------------------------------------------
[57] Run test application ($RTE_TARGET/app/test)
[58] Run testpmd application in interactive mode ($RTE_TARGET/app/testpmd)
...
[65] Exit Script
Option: 58
Enter hex bitmask of cores to execute testpmd app on
Example: to execute app on cores 0 to 7, enter 0xff
bitmask: 0xc # 二进制为 1100，表示把 CPU 的 3,4 分配给app
Launching app
EAL: Detected 4 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: No available hugepages reported in hugepages-1048576kB
EAL: Probing VFIO support...
EAL: VFIO support initialized
EAL: PCI device 0000:02:06.0 on NUMA socket -1
EAL: Invalid NUMA socket, default to 0
EAL: probe driver: 8086:100f net_e1000_em
EAL: PCI device 0000:03:00.0 on NUMA socket -1
EAL: Invalid NUMA socket, default to 0
EAL: probe driver: 15ad:7b0 net_vmxnet3
Interactive-mode selected
Failed to set MTU to 1500 for port 0
testpmd: create a new mbuf pool <mbuf_pool_socket_0>: n=155456, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc
Warning! port-topology=paired and odd forward ports number, the last port will pair with itself.
Configuring Port 0 (socket 0)
Port 0: 00:50:56:30:10:14
Checking link statuses...
Done
testpmd>
testpmd> show port info 0
********************* Infos for port 0 *********************
MAC address: 00:50:56:30:10:14
Device name: 0000:03:00.0
Driver name: net_vmxnet3
Connect to socket: 0
memory allocation on the socket: 0
Link status: up
Link speed: 10000 Mbps
Link duplex: full-duplex
MTU: 1500
Promiscuous mode: enabled
Allmulticast mode: disabled
Maximum number of MAC addresses: 1
Maximum number of MAC addresses of hash filtering: 0
VLAN offload:
strip off, filter off, extend off, qinq strip off
Supported RSS offload flow types:
ipv4
ipv4-tcp
ipv6
ipv6-tcp
Minimum size of RX buffer: 1646
Maximum configurable length of RX packet: 16384
Maximum configurable size of LRO aggregated packet: 0
Current number of RX queues: 1
Max possible RX queues: 16
Max possible number of RXDs per queue: 4096
Min possible number of RXDs per queue: 128
RXDs number alignment: 1
Current number of TX queues: 1
Max possible TX queues: 8
Max possible number of TXDs per queue: 4096
Min possible number of TXDs per queue: 512
TXDs number alignment: 1
Max segment number per packet: 255
Max segment number per MTU/TSO: 16
TestPMD可以使用如下几种不同的转发模式。
输入/输出模式（INPUT/OUTPUT MODE）
此模式通常称为IO模式，是最常用的转发模式，也是TestPMD启动时的默认模式。 在IO模式下，CPU内核从一个端口接收数据包（Rx），并将其发送到另一个端口（Tx）。 如果需要的话，一个端口可同时用于接收和发送。
收包模式（RX-ONLY MODE）
在此模式下，应用程序会轮询Rx端口的数据包，然后直接释放而不发送。 它以这种方式充当数据包接收器。
发包模式（TX-ONLY MODE）
在此模式下，应用程序生成64字节的IP数据包，并从Tx端口发送出去。 它不接收数据包，仅作为数据包源。
后两种模式（收包模式和发包模式）对于单独检查收包或者发包非常有用。
除了这三种模式，TestPMD文档中还介绍了其他一些转发模式。
执行命令sudo ./build/app/testpmd –l 0,1,2 –n 4 – -i
在此例中， –l选项指定了逻辑核。核0用于管理命令行，核1和2将用于转发数据包。 -n选项用于指定系统的内存通道数。–（破折号）分开了EAL参数和应用程序参数。-i选项运行在交互模式（交互模式下通过命令行改变转发配置）
set fwd rxonly 收包模式
set fwd txonly 发包模式
show port stats all 查看端口统计信息
clear port stats all 清除端口统计信息
show config fwd 查看转发配置
set nbcore 2 启用两个核转发
查看转发配置 show config fwd
开始转发 start
查看端口统计信息show port stats all
结束转发stop
链接：https://www.jianshu.com/p/0ac29ac0936e
testpmd
$ testpmd
EAL: Detected 4 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: No free hugepages reported in hugepages-1048576kB
EAL: Probing VFIO support...
testpmd: No probed ethernet devices
testpmd: create a new mbuf pool <mbuf_pool_socket_0>: n=171456, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc
EAL: Error - exiting with code: 1
Cause: Creation of mbuf pool for socket 0 failed: Cannot allocate memory
该问题是由于 hugepage 分配的太小导致，可以适当的增大 hugepage 即可正常。
$ testpmd --help
EAL: Detected 4 lcore(s)
EAL: Detected 1 NUMA nodes
Usage: testpmd [options]
EAL common options:
-c COREMASK Hexadecimal bitmask of cores to run on
-l CORELIST List of cores to run on
The argument format is <c1>[-c2][,c3[-c4],...]
where c1, c2, etc are core indexes between 0 and 128
--lcores COREMAP Map lcore set to physical cpu set
The argument format is
'<lcores[@cpus]>[<,lcores[@cpus]>...]'
lcores and cpus list are grouped by '(' and ')'
Within the group, '-' is used for range separator,
',' is used for single number separator.
'( )' can be omitted for single element group,
'@' can be omitted if cpus and lcores have the same value
-s SERVICE COREMASK Hexadecimal bitmask of cores to be used as service cores
--master-lcore ID Core ID that is used as master
--mbuf-pool-ops-name Pool ops name for mbuf to use
-n CHANNELS Number of memory channels
-m MB Memory to allocate (see also --socket-mem)
-r RANKS Force number of memory ranks (don't detect)
-b, --pci-blacklist Add a PCI device in black list.
Prevent EAL from using this PCI device. The argument
format is <domain:bus:devid.func>.
-w, --pci-whitelist Add a PCI device in white list.
Only use the specified PCI devices. The argument format
is <[domain:]bus:devid.func>. This option can be present
several times (once per device).
[NOTE: PCI whitelist cannot be used with -b option]
--vdev Add a virtual device.
The argument format is <driver><id>[,key=val,...]
(ex: --vdev=net_pcap0,iface=eth2).
--iova-mode Set IOVA mode. 'pa' for IOVA_PA
'va' for IOVA_VA
-d LIB.so|DIR Add a driver or driver directory
(can be used multiple times)
--vmware-tsc-map Use VMware TSC map instead of native RDTSC
--proc-type Type of this process (primary|secondary|auto)
--syslog Set syslog facility
--log-level=<int> Set global log level
--log-level=<type-match>:<int>
Set specific log level
-v Display version information on startup
-h, --help This help
--in-memory Operate entirely in memory. This will
disable secondary process support
EAL options for DEBUG use only:
--huge-unlink Unlink hugepage files after init
--no-huge Use malloc instead of hugetlbfs
--no-pci Disable PCI
--no-hpet Disable HPET
--no-shconf No shared config (mmap'd files)
EAL Linux options:
--socket-mem Memory to allocate on sockets (comma separated values)
--socket-limit Limit memory allocation on sockets (comma separated values)
--huge-dir Directory where hugetlbfs is mounted
--file-prefix Prefix for hugepage filenames
--base-virtaddr Base virtual address
--create-uio-dev Create /dev/uioX (usually done by hotplug)
--vfio-intr Interrupt mode for VFIO (legacy|msi|msix)
--legacy-mem Legacy memory mode (no dynamic allocation, contiguous segments)
--single-file-segments Put all hugepage memory in single files
$ testpmd -l 2,3 --socket-mem 1024 -n 4 --log-level=8 -- -i
EAL: Detected 4 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: No free hugepages reported in hugepages-1048576kB
EAL: Probing VFIO support...
testpmd: No probed ethernet devices
Interactive-mode selected
testpmd: create a new mbuf pool <mbuf_pool_socket_0>: n=155456, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc
Done
testpmd>
-l：指定运行 TestPMD 的 lcore，Core 1 用于管理命令行，Core 2、3 用于转发数据包
-n：指定系统的内存通道数
–：用于分开 EAL 参数和应用程序参数
testpmd> show port stats all
testpmd> show config fwd
io packet forwarding - ports=0 - cores=0 - streams=0 - NUMA support enabled, MP allocation mode: native
- must-read-for-dpdk-beginner
用户空间IO（UIO）驱动程序
testpmd> start tx_first
testpmd> stop