mlx5/connectx-4 out of order packets w/ a single queue?

charles.myers · April 28, 2017, 5:29am

Hi,

I am writing packet generation/analysis software using the ConnectX-4 (mlx5) DPDK driver.

With all other NICs I have tried (including ConnectX-3) when only a single queue on an interface is used

all packets are usually received in the order they are sent regardless of changing IP/MAC addresses

because RSS is not being used.

Is the ConnectX-4 doing RX flow classification/analysis all the time which would cause this?

Is there a way to turn it off?

I am using DPDK 16.11 with Mellanox 4.0-1.5.2.0 kernel drivers w/ linux 4.4 kernel in a VM running on QEMU/KVM w/ PCI passthru.

ConnectX-4 EN

Firmware: 12.18.2000

Board ID: MT_2150110033

Attached is a simple program which reproduces the issue.

See the readme.txt file in the .tgz file for additional details and description of program.

I thought the issue might be caused by the WQ indirection in the DPDK driver so I modified the

DPDK mlx5 driver code to use a QP directly, but there are still out of order packet issues.

Any idea why this is occurring?

Thanks,

Charles