[PATCH v3 3/3] examples/l3fwd-power: enable PMD power monitor on Arm

[Feifei Wang <feifei.wang2@arm.com>]

For Arm aarch, power monitor uses WFE instruction to enable, which can
not exit automatically within the time limit. This means
'rte_power_monitor_wakeup' API needs to be called to wake up sleep cores
if there is no store operation to monitored address.

Furthermore, we disable power monitor feature on the main core so that
it can be used to wake up other sleeping cores after it exit from loop.

Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: David Hunt <david.hunt@intel.com>
---
 examples/l3fwd-power/main.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/examples/l3fwd-power/main.c b/examples/l3fwd-power/main.c
index fd3ade330f..7c41159c43 100644
--- a/examples/l3fwd-power/main.c
+++ b/examples/l3fwd-power/main.c
@@ -3006,6 +3006,18 @@ main(int argc, char **argv)
 						"Error setting scaling freq max: err=%d, lcore %d\n",
 							ret, lcore_id);
 
+#if defined(RTE_ARCH_ARM64)
+				/* Ensure the main lcore does not enter the power-monitor state,
+				 * so that it can be used to wake up other lcores on ARM.
+				 * This is due to WFE instruction has no timeout wake-up mechanism,
+				 * and if users want to exit actively, the main lcore is needed
+				 * to send SEV instruction to wake up other lcores.
+				 */
+				unsigned int main_lcore = rte_get_main_lcore();
+				if (lcore_id == main_lcore &&
+						pmgmt_type == RTE_POWER_MGMT_TYPE_MONITOR)
+					continue;
+#endif
 				ret = rte_power_ethdev_pmgmt_queue_enable(
 						lcore_id, portid, queueid,
 						pmgmt_type);
@@ -3113,6 +3125,19 @@ main(int argc, char **argv)
 	if (app_mode == APP_MODE_EMPTY_POLL || app_mode == APP_MODE_TELEMETRY)
 		launch_timer(rte_lcore_id());
 
+	/* wake up all worker cores from sleeping state */
+	if (pmgmt_type == RTE_POWER_MGMT_TYPE_MONITOR) {
+		for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
+			if (rte_lcore_is_enabled(lcore_id) == 0)
+				continue;
+
+			if (lcore_id == rte_get_main_lcore())
+				continue;
+
+			rte_power_monitor_wakeup(lcore_id);
+		}
+	}
+
 	RTE_LCORE_FOREACH_WORKER(lcore_id) {
 		if (rte_eal_wait_lcore(lcore_id) < 0)
 			return -1;
-- 
2.25.1