1474a341d5
The example shown for registering telemetry commands was previously
missing the help text parameter.
Fixes: 24cd1b529f35 ("doc: update telemetry guides")
Signed-off-by: Ciara Power <ciara.power@intel.com>
Reviewed-by: Kevin Laatz <kevin.laatz@intel.com>
63 lines
2.5 KiB
ReStructuredText
63 lines
2.5 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2020 Intel Corporation.
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Telemetry Library
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=================
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The Telemetry library provides an interface to retrieve information from a
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variety of DPDK libraries. The library provides this information via socket
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connection, taking requests from a connected client and replying with the JSON
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response containing the requested telemetry information.
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Telemetry is enabled to run by default when running a DPDK application, and the
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telemetry information from enabled libraries is made available. Libraries are
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responsible for registering their own commands, and providing the callback
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function that will format the library specific stats into the correct data
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format, when requested.
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Registering Commands
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--------------------
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Libraries and applications must register commands to make their information
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available via the Telemetry library. This involves providing a string command
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in the required format ("/library/command"), the callback function that
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will handle formatting the information when required, and help text for the
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command. An example showing ethdev commands being registered is shown below:
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.. code-block:: c
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rte_telemetry_register_cmd("/ethdev/list", handle_port_list,
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"Returns list of available ethdev ports. Takes no parameters");
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rte_telemetry_register_cmd("/ethdev/xstats", handle_port_xstats,
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"Returns the extended stats for a port. Parameters: int port_id");
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rte_telemetry_register_cmd("/ethdev/link_status", handle_port_link_status,
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"Returns the link status for a port. Parameters: int port_id");
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Formatting JSON response
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------------------------
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The callback function provided by the library must format its telemetry
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information in the required data format. The Telemetry library provides a data
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utilities API to build up the response. For example, the ethdev library provides a
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list of available ethdev ports in a formatted data response, constructed using the
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following functions to build up the list:
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.. code-block:: c
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rte_tel_data_start_array(d, RTE_TEL_INT_VAL);
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RTE_ETH_FOREACH_DEV(port_id)
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rte_tel_data_add_array_int(d, port_id);
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The data structure is then formatted into a JSON response before sending.
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The resulting response shows the port list data provided above by the handler
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function in ethdev, placed in a JSON reply by telemetry:
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.. code-block:: console
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{"/ethdev/list": [0, 1]}
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For more information on the range of data functions available in the API,
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please refer to the docs.
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