Throughput caps at 6.9Gbps with Intel® Ethernet Network Adapter E810-XXVDA2

[AntGeorge]

Hello,

I am using the optical SFP Intel E25GSFP28SR installed in a Intel® Ethernet Network Adapter E810-XXVDA2. The operational system is Windows Server 2022 Standard.

The server contains two of these PCI cards/SFPs connected as loopback (one port of the first Card is connected to the other port of the second card).

Both of the cards are configured with

Speed & Duplex: 10 Gbps Full Duplex

Flow Control: Enabled

Tx/Rx Buffers: 4096

(also other properties are configured based on our application, like Jumbo frames size to 4096)

The goal is to achieve as high as possible throughput when transmitting UDP traffic.

When the Flow Control is Enabled we can only achieve 6.9Gbps.

When the Flow Control is Disabled we can achieve up to 9.9Gbps.

A similar test was performed using the Intel® Ethernet Network Adapter X710 and a copper SFP and with Flow Control Enabled we achieved 9.9Gbps.

So my question is whether there are other options at E810-XXVDA2 that might limit the receive buffer queues at the Flow Control logic and transmits pause frames more often than the X710.

Or if there are other settings than might effect the throughput.

Thanks,

George

[AntGeorge · Accepted solution]

It seems that the issue was that the E810 Network card was not installed at the appropriate PCI slot. Card supports PCIe 4.0 x8 but it was installed in a PCIe 3.0 at x1 lane which made the reception port to throttle the transmitter (since Flow Control was enabled) at the speed of 6.9Gbps