Bluetooth: Controller: Use reschedule margin as minimum ticks_slot

Use reschedule margin as minimum ticks_slot when ticker with reschedule expires. This will ensure not too many unreserved tickers expire in close proximity that can lead of pile up of CPU processing time and eventually causing timeout callbacks to be delayed. This mitigate possible LL asserts due to overhead in start of radio events. Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>
zephyrproject-rtos · May 2, 2024 · 64f4130 · 64f4130
1 parent 263357e
commit 64f4130
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Showing 2 changed files with 36 additions and 8 deletions.
diff --git a/subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/ticker.h b/subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/ticker.h
@@ -68,8 +68,9 @@
 	HAL_TICKER_TICKS_TO_US(HAL_TICKER_PSEC_PER_USEC)
 
 /* Macro defining the margin for positioning re-scheduled nodes */
+#define HAL_TICKER_RESCHEDULE_MARGIN_US 150U
 #define HAL_TICKER_RESCHEDULE_MARGIN \
-	HAL_TICKER_US_TO_TICKS(150)
+	HAL_TICKER_US_TO_TICKS(HAL_TICKER_RESCHEDULE_MARGIN_US)
 
 /* Remove ticks and return positive remainder value in microseconds */
 static inline void hal_ticker_remove_jitter(uint32_t *ticks,

diff --git a/subsys/bluetooth/controller/ticker/ticker.c b/subsys/bluetooth/controller/ticker/ticker.c
@@ -840,15 +840,25 @@ static uint8_t ticker_resolve_collision(struct ticker_node *nodes,
 
 		while (id_head != TICKER_NULL) {
 			struct ticker_node *ticker_next = &nodes[id_head];
+			uint32_t ticker_next_ticks_slot;
 
 			/* Accumulate ticks_to_expire for each node */
 			acc_ticks_to_expire += ticker_next->ticks_to_expire;
 			if (acc_ticks_to_expire > ticker_ticks_slot) {
 				break;
 			}
 
+			if (TICKER_HAS_SLOT_WINDOW(ticker_next) &&
+			    (ticker_next->ticks_slot == 0U)) {
+				ticker_next_ticks_slot =
+					HAL_TICKER_RESCHEDULE_MARGIN;
+			} else {
+				ticker_next_ticks_slot =
+					ticker_next->ticks_slot;
+			}
+
 			/* We only care about nodes with slot reservation */
-			if (ticker_next->ticks_slot == 0U) {
+			if (ticker_next_ticks_slot == 0U) {
 				id_head = ticker_next->next;
 				continue;
 			}
@@ -977,7 +987,8 @@ static uint8_t ticker_resolve_collision(struct ticker_node *nodes,
 			/* Check if next node is within this reservation slot
 			 * and wins conflict resolution
 			 */
-			if (curr_has_ticks_slot_window ||
+			if ((curr_has_ticks_slot_window &&
+			     next_not_ticks_slot_window) ||
 			    (!lazy_next_periodic_skip &&
 			     (next_is_critical ||
 			      next_force ||
@@ -1295,11 +1306,19 @@ void ticker_worker(void *param)
 
 #if !defined(CONFIG_BT_TICKER_LOW_LAT) && \
 	!defined(CONFIG_BT_TICKER_SLOT_AGNOSTIC)
+		uint32_t ticker_ticks_slot;
+
+		if (TICKER_HAS_SLOT_WINDOW(ticker) &&
+		    (ticker->ticks_slot == 0U)) {
+			ticker_ticks_slot = HAL_TICKER_RESCHEDULE_MARGIN;
+		} else {
+			ticker_ticks_slot = ticker->ticks_slot;
+		}
+
 		/* Check if node has slot reservation and resolve any collision
 		 * with other ticker nodes
 		 */
-		if (((ticker->ticks_slot != 0U) ||
-		      TICKER_HAS_SLOT_WINDOW(ticker)) &&
+		if ((ticker_ticks_slot != 0U) &&
 		    (slot_reserved ||
 		     (instance->ticks_slot_previous > ticks_expired) ||
 		     ticker_resolve_collision(node, ticker))) {
@@ -1431,7 +1450,7 @@ void ticker_worker(void *param)
 
 #if !defined(CONFIG_BT_TICKER_LOW_LAT) && \
 	!defined(CONFIG_BT_TICKER_SLOT_AGNOSTIC)
-				if (ticker->ticks_slot != 0U) {
+				if (ticker_ticks_slot != 0U) {
 					/* Any further nodes will be skipped */
 					slot_reserved = 1U;
 				}
@@ -2061,13 +2080,21 @@ static inline void ticker_job_worker_bh(struct ticker_instance *instance,
 			instance->ticks_slot_previous = 0U;
 		}
 
+		uint32_t ticker_ticks_slot;
+
+		if (TICKER_HAS_SLOT_WINDOW(ticker) && !ticker->ticks_slot) {
+			ticker_ticks_slot = HAL_TICKER_RESCHEDULE_MARGIN;
+		} else {
+			ticker_ticks_slot = ticker->ticks_slot;
+		}
+
 		/* If a reschedule is set pending, we will need to keep
 		 * the slot_previous information
 		 */
-		if (ticker->ticks_slot && (state == 2U) && !skip_collision &&
+		if (ticker_ticks_slot && (state == 2U) && !skip_collision &&
 		    !TICKER_RESCHEDULE_PENDING(ticker)) {
 			instance->ticker_id_slot_previous = id_expired;
-			instance->ticks_slot_previous = ticker->ticks_slot;
+			instance->ticks_slot_previous = ticker_ticks_slot;
 		}
 #endif /* CONFIG_BT_TICKER_SLOT_AGNOSTIC */