sys/event: add event loop debug threshold

Author: kfessel

sys/include/event.h

@@ -405,6 +405,17 @@ event_t *event_wait_timeout_ztimer(event_queue_t *queue,
                                    ztimer_clock_t *clock, uint32_t timeout);
 #endif
 
+/**
+ * @brief Threshold (USEC) below which event_handler are not printed,
+ *        while debugging eventloop setting a value (!0) will also remove
+ *        event_handler start message
+ *
+ *        Use this to prevent *a lot* of output when debugging.
+ */
+#ifndef CONFIG_EVENT_LOOP_DEBUG_THRESHOLD
+#define CONFIG_EVENT_LOOP_DEBUG_THRESHOLD  (0)
+#endif
+
 /**
  * @brief   Simple event loop with multiple queues
  *
@@ -442,17 +453,23 @@ static inline void event_loop_multi(event_queue_t *queues, size_t n_queues)
             ztimer_acquire(ZTIMER_USEC);
 
             void _event_callback_handler(event_t *event);
-            if (!IS_USED(MODULE_EVENT_CALLBACK) ||
-                event->handler != _event_callback_handler) {
+            if ((CONFIG_EVENT_LOOP_DEBUG_THRESHOLD == 0) &&
+                (!IS_USED(MODULE_EVENT_CALLBACK) ||
+                event->handler != _event_callback_handler)) {
                 printf("event: executing %p->%p\n",
                        (void *)event, (void *)(uintptr_t)event->handler);
             }
             now = ztimer_now(ZTIMER_USEC);
-
+            void * h =  event->handler;
             event->handler(event);
 
-            printf("event: %p took %" PRIu32 " µs\n",
-                   (void *)event, ztimer_now(ZTIMER_USEC) - now);
+            uint32_t now2 = ztimer_now(ZTIMER_USEC);
+            uint32_t dt = now2 - now;
+
+            if ((CONFIG_EVENT_LOOP_DEBUG_THRESHOLD == 0) || dt > CONFIG_EVENT_LOOP_DEBUG_THRESHOLD) {
+                printf("eventh: %p took %" PRIu32 " µs\n",
+                       (void *)h, dt);
+            }
             ztimer_release(ZTIMER_USEC);
         }
         else {