.. 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
-
- /* init EAL */
-
- ret = rte_eal_init(argc, argv);
- if (ret < 0)
- rte_panic("Cannot init EAL\n");
-
- /* init RTE timer library */
-
- rte_timer_subsystem_init();
+.. 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.
-.. code-block:: c
-
- /* call lcore_mainloop() on every worker lcore */
- RTE_LCORE_FOREACH_WORKER(lcore_id) {
- rte_eal_remote_launch(lcore_mainloop, NULL, lcore_id);
- }
-
- /* call it on main 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 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 main 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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