Max link speed of E810-CAM2 on Windows

[gitcchi]

I am using a Intel E810-CAM2 based pcie card, with a QSFP28 passive cable. My development platform is Windows 11 and with this config I am limited to 8-9Gbps.
I am only getting a link speed of 10g instead of 100g, which is what I believe is limiting the performance.
MT: 2023-12-24 01:26:44, mt_eth_link_dump(0), link_speed 10g link_status 1 link_duplex 1 link_autoneg 1

Am I missing something or is this normal behavior due to some lacking driver/runtime support on Windows?

[frankdjx]

Our Windows setup successfully achieves the full 100Gbps with the E810 NIC. The 10Gbps link speed might result from hardware negotiation issues between the NIC and the switch. I have two clarifications to request:

What is the link speed when the NIC uses the default Windows driver?
Have you encountered a similar issue when operating under a Linux OS?

[gitcchi]

I am not using a switch, the ports on the card are connected directly to each other. It serves as a minimal dev environment.

When in using the default driver (E810-C for QSFP) it shows 10Gbps with auto negotiation. If I force both ports to 100Gbps they will connect with that speed.
I have no Linux setup for this this card, so I cannot tell you what happens there.

Is it possible to disable autoneg and force network link speeds with MTL and the netuio driver?

[frankdjx]

Seems like the 100g cable used has compatible problem on the auto negotiation. Can you find another one?

And for the fixed speed, link_speeds can be specified in struct rte_eth_conf

struct rte_eth_conf {
	uint32_t link_speeds; /**< bitmap of RTE_ETH_LINK_SPEED_XXX of speeds to be
				used. RTE_ETH_LINK_SPEED_FIXED disables link
				autonegotiation, and a unique speed shall be
				set. Otherwise, the bitmap defines the set of
				speeds to be advertised. If the special value
				RTE_ETH_LINK_SPEED_AUTONEG (0) is used, all speeds
				supported are advertised. */

Below is the code part of MTL to initial struct rte_eth_conf, can you try if below diff works for your case.

git diff
diff --git a/lib/src/dev/mt_dev.c b/lib/src/dev/mt_dev.c
index d0fb891..7316565 100644
--- a/lib/src/dev/mt_dev.c
+++ b/lib/src/dev/mt_dev.c
@@ -916,6 +916,7 @@ static int dev_config_port(struct mt_interface* inf) {
     port_conf.rxmode.mq_mode = RTE_ETH_MQ_RX_RSS;
   }

+  port_conf.link_speeds = RTE_ETH_LINK_SPEED_100G;
   ret = rte_eth_dev_configure(port_id, nb_rx_q, nb_tx_q, &port_conf);
   if (ret < 0) {
     err("%s(%d), rte_eth_dev_configure fail %d\n", __func__, port, ret);