mirror of https://github.com/F-Stack/f-stack.git
110 lines
3.7 KiB
ReStructuredText
110 lines
3.7 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
|
|
Copyright(c) 2010-2014 Intel Corporation.
|
|
|
|
Timer Sample Application
|
|
========================
|
|
|
|
The Timer sample application is a simple application that demonstrates the use of a timer in a DPDK application.
|
|
This application prints some messages from different lcores regularly, demonstrating the use of timers.
|
|
|
|
Compiling the Application
|
|
-------------------------
|
|
|
|
To compile the sample application see :doc:`compiling`.
|
|
|
|
The application is located in the ``timer`` sub-directory.
|
|
|
|
Running the Application
|
|
-----------------------
|
|
|
|
To run the example in linux environment:
|
|
|
|
.. code-block:: console
|
|
|
|
$ ./<build_dir>/examples/dpdk-timer -l 0-3 -n 4
|
|
|
|
Refer to the *DPDK Getting Started Guide* for general information on running applications and
|
|
the Environment Abstraction Layer (EAL) options.
|
|
|
|
Explanation
|
|
-----------
|
|
|
|
The following sections provide some explanation of the code.
|
|
|
|
Initialization and Main Loop
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
In addition to EAL initialization, the timer subsystem must be initialized, by calling the rte_timer_subsystem_init() function.
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: Init EAL. 8<
|
|
:end-before: >8 End of init EAL.
|
|
:dedent: 1
|
|
|
|
After timer creation (see the next paragraph), the main loop is
|
|
executed on each worker lcore using the well-known
|
|
rte_eal_remote_launch() and also on the main.
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: Call lcore_mainloop() on every worker lcore. 8<
|
|
:end-before: >8 End of call lcore_mainloop() on every worker lcore.
|
|
:dedent: 1
|
|
|
|
The main loop is very simple in this example:
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: Main loop. 8<
|
|
:end-before: >8 End of main loop.
|
|
:dedent: 1
|
|
|
|
As explained in the comment, it is better to use the TSC register (as it is a per-lcore register) to check if the
|
|
rte_timer_manage() function must be called or not.
|
|
In this example, the resolution of the timer is 10 milliseconds.
|
|
|
|
Managing Timers
|
|
~~~~~~~~~~~~~~~
|
|
|
|
In the main() function, the two timers are initialized.
|
|
This call to rte_timer_init() is necessary before doing any other operation on the timer structure.
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: Init timer structures. 8<
|
|
:end-before: >8 End of init timer structures.
|
|
:dedent: 1
|
|
|
|
Then, the two timers are configured:
|
|
|
|
* The first timer (timer0) is loaded on the main lcore and expires every second.
|
|
Since the PERIODICAL flag is provided, the timer is reloaded automatically by the timer subsystem.
|
|
The callback function is timer0_cb().
|
|
|
|
* The second timer (timer1) is loaded on the next available lcore every 333 ms.
|
|
The SINGLE flag means that the timer expires only once and must be reloaded manually if required.
|
|
The callback function is timer1_cb().
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: Load timer0, every second, on main lcore, reloaded automatically. 8<
|
|
:end-before: >8 End of two timers configured.
|
|
:dedent: 1
|
|
|
|
The callback for the first timer (timer0) only displays a message until a global counter reaches 20 (after 20 seconds).
|
|
In this case, the timer is stopped using the rte_timer_stop() function.
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: timer0 callback. 8<
|
|
:end-before: >8 End of timer0 callback.
|
|
|
|
The callback for the second timer (timer1) displays a message and reloads the timer on the next lcore, using the
|
|
rte_timer_reset() function:
|
|
|
|
.. literalinclude:: ../../../examples/timer/main.c
|
|
:language: c
|
|
:start-after: timer1 callback. 8<
|
|
:end-before: >8 End of timer1 callback.
|