..  SPDX-License-Identifier: BSD-3-Clause
    Copyright(c) 2020 Intel Corporation.


DPDK Telemetry User Guide
=========================

The Telemetry library provides users with the ability to query DPDK for
telemetry information, currently including information such as ethdev stats,
ethdev port list, and eal parameters.

.. Note::

   This library is experimental and the output format may change in the future.


Telemetry Interface
-------------------

The :doc:`../prog_guide/telemetry_lib` opens a socket with path
*<runtime_directory>/dpdk_telemetry.<version>*. The version represents the
telemetry version, the latest is v2. For example, a client would connect to a
socket with path  */var/run/dpdk/\*/dpdk_telemetry.v2* (when the primary process
is run by a root user).


Telemetry Initialization
------------------------

The library is enabled by default, however an EAL flag to enable the library
exists, to provide backward compatibility for the previous telemetry library
interface::

  --telemetry

A flag exists to disable Telemetry also::

  --no-telemetry


Running Telemetry
-----------------

The following steps show how to run an application with telemetry support,
and query information using the telemetry client python script.

#. Launch testpmd as the primary application with telemetry::

      ./app/dpdk-testpmd

#. Launch the telemetry client script::

      ./usertools/dpdk-telemetry.py

#. When connected, the script displays the following, waiting for user input::

     Connecting to /var/run/dpdk/rte/dpdk_telemetry.v2
     {"version": "DPDK 20.05.0-rc2", "pid": 60285, "max_output_len": 16384}
     -->

#. The user can now input commands to send across the socket, and receive the
   response. Some available commands are shown below.

   * List all commands::

       --> /
       {"/": ["/", "/eal/app_params", "/eal/params", "/ethdev/list",
       "/ethdev/link_status", "/ethdev/xstats", "/help", "/info"]}

   * Get the list of ethdev ports::

       --> /ethdev/list
       {"/ethdev/list": [0, 1]}

   .. Note::

      For commands that expect a parameter, use "," to separate the command
      and parameter. See examples below.

   * Get extended statistics for an ethdev port::

       --> /ethdev/xstats,0
       {"/ethdev/xstats": {"rx_good_packets": 0, "tx_good_packets": 0,
       "rx_good_bytes": 0, "tx_good_bytes": 0, "rx_missed_errors": 0,
       ...
       "tx_priority7_xon_to_xoff_packets": 0}}

   * Get the help text for a command. This will indicate what parameters are
     required. Pass the command as a parameter::

       --> /help,/ethdev/xstats
       {"/help": {"/ethdev/xstats": "Returns the extended stats for a port.
       Parameters: int port_id"}}
