Low (weird) throughput with ConnectX-3

Dear all,

I have a problem when receiving traffic with Mellanox ConnectX-3 VPI (dual 40Gbps ports).

Problem description: I connect the two 40G ports to tow traffic generator (shown as below). When G#1 sends traffic (128B packets), port 1 of the server can receive packets with 28Gbps. However, while G#2 send traffic to port 2 concurrently, the traffic speed of port 1 becomes 14Gbps and that of port 2 is also 14Gbps.

Naturally, the total traffic of two ports should be 56Gbps (28 * 2), not be divided 14Gbps per port.

So, Is there a reasonable comment about this problem, or is there some problem in my system setting?

Additional information: I have tuned performance guided by the document( ) and my PCI-E speed is 8GB (PCI-E 3.0 8x).

Can anyone help me with this problem?

Many thanks,



I use the Ethernet mode.

The totally capacity of chipset is about 26Mpps.

Mellanox NIC use 1 chipset in each card.

So seems you can’t get more performance when you use dual port

You use InfiniBand or Ethernet mode ?