This patch adds examples to the Telemetry HowTo guide, to demonstrate
commands that use parameters. The programmer's guide is also modified to
include details on writing a callback function for a new command.
Signed-off-by: Ciara Power <ciara.po...@intel.com>
---
v3:
- Replaced direct code examples with generic examples.
- Replaced ref label with :doc: syntax to link guides.
- Replaced console code-block label with :: on previous lines.
- Added links to API doc.
- Modified some formatting.
v2:
- Replaced examples of using commands in the programmer's guide with
a link to the HowTo guide.
- Added an example showing the use of a single string value.
- Replaced inline functions with a synthetic example function below
the list of parameters.
---
doc/guides/howto/telemetry.rst | 67 ++++++----
doc/guides/prog_guide/telemetry_lib.rst | 160 +++++++++++++++++++-----
2 files changed, 172 insertions(+), 55 deletions(-)
diff --git a/doc/guides/howto/telemetry.rst b/doc/guides/howto/telemetry.rst
index b4a34ed674..e7b5434152 100644
--- a/doc/guides/howto/telemetry.rst
+++ b/doc/guides/howto/telemetry.rst
@@ -29,17 +29,13 @@ 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.
+interface::
-.. code-block:: console
+ --telemetry
- --telemetry
+A flag exists to disable Telemetry also::
-A flag exists to disable Telemetry also.
-
-.. code-block:: console
-
- --no-telemetry
+ --no-telemetry
Running Telemetry
@@ -48,33 +44,50 @@ 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.
-
- .. code-block:: console
+#. Launch testpmd as the primary application with telemetry::
./app/dpdk-testpmd
-#. Launch the telemetry client script.
-
- .. code-block:: console
+#. Launch the telemetry client script::
python usertools/dpdk-telemetry.py
-#. When connected, the script displays the following, waiting for user input.
+#. When connected, the script displays the following, waiting for user input::
- .. code-block:: console
-
- Connecting to /var/run/dpdk/rte/dpdk_telemetry.v2
- {"version": "DPDK 20.05.0-rc0", "pid": 60285, "max_output_len": 16384}
- -->
+ 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.
+ 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}}
- .. code-block:: console
+ * Get the help text for a command. This will indicate what parameters are
+ required. Pass the command as a parameter::
- --> /
- {"/": ["/", "/eal/app_params", "/eal/params", "/ethdev/list",
- "/ethdev/link_status", "/ethdev/xstats", "/help", "/info"]}
- --> /ethdev/list
- {"/ethdev/list": [0, 1]}
+ --> /help,/ethdev/xstats
+ {"/help": {"/ethdev/xstats": "Returns the extended stats for a port.
+ Parameters: int port_id"}}
diff --git a/doc/guides/prog_guide/telemetry_lib.rst
b/doc/guides/prog_guide/telemetry_lib.rst
index 8563a7200e..c01e2480ce 100644
--- a/doc/guides/prog_guide/telemetry_lib.rst
+++ b/doc/guides/prog_guide/telemetry_lib.rst
@@ -16,47 +16,151 @@ function that will format the library specific stats into
the correct data
format, when requested.
-Registering Commands
---------------------
+Creating Callback Functions
+---------------------------
-Libraries and applications must register commands to make their information
-available via the Telemetry library. This involves providing a string command
-in the required format ("/library/command"), the callback function that
-will handle formatting the information when required, and help text for the
-command. An example showing ethdev commands being registered is shown below:
+
+Function Type
+~~~~~~~~~~~~~
+
+When creating a callback function in a library/app, it must be of the
following type:
.. code-block:: c
- rte_telemetry_register_cmd("/ethdev/list", handle_port_list,
- "Returns list of available ethdev ports. Takes no parameters");
- rte_telemetry_register_cmd("/ethdev/xstats", handle_port_xstats,
- "Returns the extended stats for a port. Parameters: int port_id");
- rte_telemetry_register_cmd("/ethdev/link_status", handle_port_link_status,
- "Returns the link status for a port. Parameters: int port_id");
+ typedef int (*telemetry_cb)(const char *cmd, const char *params,
+ struct rte_tel_data *info);
+
+An example callback function is shown below:
+
+.. code-block:: c
+ static int
+ handle_example_cmd(const char *cmd __rte_unused, const char *params
__rte_unused,
+ struct rte_tel_data *d)
-Formatting JSON response
-------------------------
+For more detail on the callback function parameters, please refer to the
+`definition in the API doc
+<https://doc.dpdk.org/api/rte__telemetry_8h.html#a41dc74d561442bb6184ee6dd1f9b5bcc>`_
+
+**Example Callback**
+
+This callback is an example of handling multiple commands in one callback,
+and also shows the use of params which holds a port ID. The params input needs
+to be validated and converted to the required integer type for port ID. The cmd
+parameter is then used in a comparison to decide which command was requested,
+which will decide what port information should fill the rte_tel_data structure.
+
+.. code-block:: c
+
+ int
+ handle_cmd_request(const char *cmd, const char *params,
+ struct rte_tel_data *d)
+ {
+ int port_id, used = 0;
+
+ if (params == NULL || strlen(params) == 0 || !isdigit(*params))
+ return -1;
+
+ port_id = atoi(params);
+ if (!rte_eth_dev_is_valid_port(port_id))
+ return -1;
+
+ if (strcmp(cmd, "/cmd_1") == 0)
+ /* Build up port data requested for command 1 */
+ else
+ /* Build up port data requested for command 2 */
+
+ return used;
+ }
+
+
+Formatting Data
+~~~~~~~~~~~~~~~
The callback function provided by the library must format its telemetry
information in the required data format. The Telemetry library provides a data
-utilities API to build up the response. For example, the ethdev library
provides a
-list of available ethdev ports in a formatted data response, constructed using
the
-following functions to build up the list:
+utilities API to build up the data structure with the required information.
+The telemetry library is then responsible for formatting the data structure
+into a JSON response before sending to the client.
-.. code-block:: c
- rte_tel_data_start_array(d, RTE_TEL_INT_VAL);
- RTE_ETH_FOREACH_DEV(port_id)
- rte_tel_data_add_array_int(d, port_id);
+Array Data
+^^^^^^^^^^
+
+ Some data will need to be formatted in a list structure. For example, if a
+ callback needs to return five integer values in the data response, it can be
+ constructed using the following functions to build up the list:
+
+ .. code-block:: c
+
+ rte_tel_data_start_array(d, RTE_TEL_INT_VAL);
+ for(i = 0; i < 5; i++)
+ rte_tel_data_add_array_int(d, i);
+
+ The resulting response to the client shows the list data provided above
+ by the handler function in the library/app, placed in a JSON reply by
+ telemetry::
-The data structure is then formatted into a JSON response before sending.
-The resulting response shows the port list data provided above by the handler
-function in ethdev, placed in a JSON reply by telemetry:
+ {"/example_lib/five_ints": [0, 1, 2, 3, 4]}
-.. code-block:: console
- {"/ethdev/list": [0, 1]}
+Dictionary Data
+^^^^^^^^^^^^^^^
+
+ For data that needs to be structured in a dictionary with key/value pairs,
+ the data utilities API can also be used. For example, some information about
+ a brownie recipe is constructed in the callback function shown below:
+
+ .. code-block:: c
+
+ rte_tel_data_start_dict(d);
+ rte_tel_data_add_dict_string(d, "Recipe", "Brownies");
+ rte_tel_data_add_dict_int(d, "Prep time (mins)", 25);
+ rte_tel_data_add_dict_int(d, "Cooking time (mins)", 30);
+ rte_tel_data_add_dict_int(d, "Serves", 16);
+
+ The resulting response to the client shows the key/value data provided above
+ by the handler function in telemetry, placed in a JSON reply by telemetry::
+
+ {"/example_lib/brownie_recipe": {"Recipe": "Brownies", "Prep time (mins)":
25,
+ "Cooking time (mins)": 30, "Serves": 16}}
+
+
+String Data
+^^^^^^^^^^^
+
+ Telemetry also supports single string data. The data utilities API can again
+ be used for this, see the example below.
+
+ .. code-block:: c
+
+ rte_tel_data_string(d, "This is an example string");
+
+ Giving the following response to the client::
+
+ {"/example_lib/string_example": "This is an example string"}
For more information on the range of data functions available in the API,
-please refer to the docs.
+please refer to the `API doc
<https://doc.dpdk.org/api-20.05/rte__telemetry_8h.html>`_
+
+
+Registering Commands
+--------------------
+
+Libraries and applications must register commands to make their information
+available via the Telemetry library. This involves providing a string command
+in the required format ("/library/command"), the callback function that
+will handle formatting the information when required, and help text for the
+command. An example command being registered is shown below:
+
+.. code-block:: c
+
+ rte_telemetry_register_cmd("/example_lib/string_example", handle_string,
+ "Returns an example string. Takes no parameters");
+
+
+Using Commands
+--------------
+
+To use commands, with a DPDK app running (e.g. testpmd), use the
+dpdk-telemetry.py script. For details on its use, see the
:doc:`../howto/telemetry`.
--
2.17.1
