Fix link speed when link is down at startup.

When link is down at startup, the link_speed returned by DPDK
is 0. This results in un-optimized latency estimates in gen and lat.
With this fix, lat and gen do nothing until link_speed is
properly initialized, and use the right link speed in the fast path.

Change-Id: Id2d14b6966ccfac7cc78db3c5a74e704b42edae7
Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>

2 files changed, 40 insertions, 8 deletions

diff --git a/VNFs/DPPD-PROX/handle_gen.c b/VNFs/DPPD-PROX/handle_gen.c
index 9bb34fc7..89dbe9e4 100644
--- a/VNFs/DPPD-PROX/handle_gen.c
+++ b/VNFs/DPPD-PROX/handle_gen.c
@@ -641,6 +641,16 @@ static int handle_gen_bulk(struct task_base *tbase, struct rte_mbuf **mbufs, uin
 
 	int i, j;
 
+	// If link is down, link_speed is 0
+	if (unlikely(task->link_speed == 0)) {
+		if (task->port && task->port->link_speed != 0) {
+			task->link_speed = task->port->link_speed * 125000L;
+			plog_info("\tPort %u: link speed is %ld Mbps\n",
+				(uint8_t)(task->port - prox_port_cfg), 8 * task->link_speed / 1000000);
+		} else
+			return 0;
+	}
+
 	task_gen_update_config(task);
 
 	if (task->pkt_count == 0) {
@@ -1145,11 +1155,17 @@ static void start(struct task_base *tbase)
 	if (tbase->l3.tmaster) {
 		register_all_ip_to_ctrl_plane(task);
 	}
-	if (task->port && task->port->link_speed) {
-		// task->port->link->speed reports the link speed in Mbps e.g. 40k for a 40 Gbps NIC
-		// task->link_speed reported link speed in Bytes per sec.
+	if (task->port) {
+		// task->port->link_speed reports the link speed in Mbps e.g. 40k for a 40 Gbps NIC.
+		// task->link_speed reports link speed in Bytes per sec.
+		// It can be 0 if link is down, and must hence be updated in fast path.
 		task->link_speed = task->port->link_speed * 125000L;
-		plog_info("\tGenerating at %ld Mbps\n", 8 * task->link_speed / 1000000);
+		if (task->link_speed)
+			plog_info("\tPort %u: link speed is %ld Mbps\n",
+				(uint8_t)(task->port - prox_port_cfg), 8 * task->link_speed / 1000000);
+		else
+			plog_info("\tPort %u: link speed is %ld Mbps - link might be down\n",
+				(uint8_t)(task->port - prox_port_cfg), 8 * task->link_speed / 1000000);
 	}
 	/* TODO
 	   Handle the case when two tasks transmit to the same port
diff --git a/VNFs/DPPD-PROX/handle_lat.c b/VNFs/DPPD-PROX/handle_lat.c
index 1fa44137..8cc5c32b 100644
--- a/VNFs/DPPD-PROX/handle_lat.c
+++ b/VNFs/DPPD-PROX/handle_lat.c
@@ -520,6 +520,16 @@ static int handle_lat_bulk(struct task_base *tbase, struct rte_mbuf **mbufs, uin
 
 	uint32_t pkt_rx_time, pkt_tx_time;
 
+	// If link is down, link_speed is 0
+	if (unlikely(task->link_speed == 0)) {
+		if (task->port && task->port->link_speed != 0) {
+			task->link_speed = task->port->link_speed * 125000L;
+			plog_info("\tPort %u: link speed is %ld Mbps\n",
+				(uint8_t)(task->port - prox_port_cfg), 8 * task->link_speed / 1000000);
+		} else
+			return 0;
+	}
+
 	if (n_pkts == 0) {
 		task->begin = tbase->aux->tsc_rx.before;
 		return 0;
@@ -688,11 +698,17 @@ static void lat_start(struct task_base *tbase)
 {
 	struct task_lat *task = (struct task_lat *)tbase;
 
-	if (task->port && task->port->link_speed) {
-		// task->port->link->speed reports the link speed in Mbps e.g. 40k for a 40 Gbps NIC
-		// task->link_speed reported link speed in Bytes per sec.
+	if (task->port) {
+		// task->port->link_speed reports the link speed in Mbps e.g. 40k for a 40 Gbps NIC.
+		// task->link_speed reports link speed in Bytes per sec.
+		// It can be 0 if link is down, and must hence be updated in fast path.
 		task->link_speed = task->port->link_speed * 125000L;
-		plog_info("\tReceiving at %lu Mbps\n", 8 * task->link_speed / 1000000);
+		if (task->link_speed)
+			plog_info("\tPort %u: link speed is %ld Mbps\n",
+				(uint8_t)(task->port - prox_port_cfg), 8 * task->link_speed / 1000000);
+		else
+			plog_info("\tPort %u: link speed is %ld Mbps - link might be down\n",
+				(uint8_t)(task->port - prox_port_cfg), 8 * task->link_speed / 1000000);
 	}
 }