30. Packet Ordering Application

The Packet Ordering sample app simply shows the impact of reordering a stream. It’s meant to stress the library with different configurations for performance.

30.1. Overview

The application uses at least three CPU cores:

  • RX core (maser core) receives traffic from the NIC ports and feeds Worker cores with traffic through SW queues.
  • Worker core (slave core) basically do some light work on the packet. Currently it modifies the output port of the packet for configurations with more than one port enabled.
  • TX Core (slave core) receives traffic from Worker cores through software queues, inserts out-of-order packets into reorder buffer, extracts ordered packets from the reorder buffer and sends them to the NIC ports for transmission.

30.2. Compiling the Application

  1. Go to the example directory:

    export RTE_SDK=/path/to/rte_sdk
cd ${RTE_SDK}/examples/helloworld

  2. Set the target (a default target is used if not specified). For example:

    export RTE_TARGET=x86_64-native-linuxapp-gcc

    See the DPDK Getting Started Guide for possible RTE_TARGET values.

  3. Build the application:

    make

30.3. Running the Application

Refer to DPDK Getting Started Guide for general information on running applications and the Environment Abstraction Layer (EAL) options.

30.3.1. Application Command Line

The application execution command line is:

./test-pipeline [EAL options] -- -p PORTMASK [--disable-reorder]

The -c EAL CPU_COREMASK option has to contain at least 3 CPU cores. The first CPU core in the core mask is the master core and would be assigned to RX core, the last to TX core and the rest to Worker cores.

The PORTMASK parameter must contain either 1 or even enabled port numbers. When setting more than 1 port, traffic would be forwarded in pairs. For example, if we enable 4 ports, traffic from port 0 to 1 and from 1 to 0, then the other pair from 2 to 3 and from 3 to 2, having [0,1] and [2,3] pairs.

The disable-reorder long option does, as its name implies, disable the reordering of traffic, which should help evaluate reordering performance impact.