.. code-block:: console
- $ ./build/timer -l 0-3 -n 4
+ $ ./<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.
In addition to EAL initialization, the timer subsystem must be initialized, by calling the rte_timer_subsystem_init() function.
-.. code-block:: c
+.. literalinclude:: ../../../examples/timer/main.c
+ :language: c
+ :start-after: Init EAL. 8<
+ :end-before: >8 End of init EAL.
+ :dedent: 1
- /* init EAL */
+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.
- ret = rte_eal_init(argc, argv);
- if (ret < 0)
- rte_panic("Cannot init EAL\n");
-
- /* init RTE timer library */
-
- rte_timer_subsystem_init();
-
-After timer creation (see the next paragraph),
-the main loop is executed on each slave lcore using the well-known rte_eal_remote_launch() and also on the master.
-
-.. code-block:: c
-
- /* call lcore_mainloop() on every slave lcore */
-
- RTE_LCORE_FOREACH_SLAVE(lcore_id) {
- rte_eal_remote_launch(lcore_mainloop, NULL, lcore_id);
- }
-
- /* call it on master lcore too */
-
- (void) lcore_mainloop(NULL);
+.. 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:
-.. code-block:: c
-
- while (1) {
- /*
- * Call the timer handler on each core: as we don't
- * need a very precise timer, so only call
- * rte_timer_manage() every ~10ms (at 2 GHz). In a real
- * application, this will enhance performances as
- * reading the HPET timer is not efficient.
- */
-
- cur_tsc = rte_rdtsc();
-
- diff_tsc = cur_tsc - prev_tsc;
-
- if (diff_tsc > TIMER_RESOLUTION_CYCLES) {
- rte_timer_manage();
- prev_tsc = cur_tsc;
- }
- }
+.. 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 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.
-.. code-block:: c
-
- /* init timer structures */
-
- rte_timer_init(&timer0);
- rte_timer_init(&timer1);
+.. 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 master lcore and expires every second.
+* 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 SINGLE flag means that the timer expires only once and must be reloaded manually if required.
The callback function is timer1_cb().
-.. code-block:: c
-
- /* load timer0, every second, on master lcore, reloaded automatically */
-
- hz = rte_get_hpet_hz();
-
- lcore_id = rte_lcore_id();
-
- rte_timer_reset(&timer0, hz, PERIODICAL, lcore_id, timer0_cb, NULL);
-
- /* load timer1, every second/3, on next lcore, reloaded manually */
-
- lcore_id = rte_get_next_lcore(lcore_id, 0, 1);
-
- rte_timer_reset(&timer1, hz/3, SINGLE, lcore_id, timer1_cb, NULL);
+.. 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.
-.. code-block:: c
-
- /* timer0 callback */
-
- static void
- timer0_cb(__rte_unused struct rte_timer *tim, __rte_unused void *arg)
- {
- static unsigned counter = 0;
-
- unsigned lcore_id = rte_lcore_id();
-
- printf("%s() on lcore %u\n", FUNCTION , lcore_id);
-
- /* this timer is automatically reloaded until we decide to stop it, when counter reaches 20. */
-
- if ((counter ++) == 20)
- rte_timer_stop(tim);
- }
+.. 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:
-.. code-block:: c
-
- /* timer1 callback */
-
- static void
- timer1_cb(__rte_unused struct rte_timer *tim, __rte_unused void *arg)
- {
- unsigned lcore_id = rte_lcore_id();
- uint64_t hz;
-
- printf("%s() on lcore %u\\n", FUNCTION , lcore_id);
-
- /* reload it on another lcore */
-
- hz = rte_get_hpet_hz();
-
- lcore_id = rte_get_next_lcore(lcore_id, 0, 1);
-
- rte_timer_reset(&timer1, hz/3, SINGLE, lcore_id, timer1_cb, NULL);
- }
+.. literalinclude:: ../../../examples/timer/main.c
+ :language: c
+ :start-after: timer1 callback. 8<
+ :end-before: >8 End of timer1 callback.
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