Re: Initial Setup and best practices

[Thomas Monjalon <thomas@monjalon.net>]

13/02/2022 18:37, Simon Brown:
> Hello,

Hello

> I'm new to DPDK and I'm trying to setup a simple project to count packets. I'm 
> using MoonGen to generate the traffic on one machine and can receive the data 
> using traditional sockets on another machine. So I know that part works.
> 
> I've built dpdk 21.11 and I've tried to modify the example rxtx callbacks 
> application to count packets, but it doesn't see any traffic. So I presume 
> there's something wrong with my environment.

You should explain more what is your setup.

> Can you advise on how to verify that my environment is correct and what is the 
> recommended setup for new projects? Should I be using the virtualisation 
> interface vfio-pci or the other interfaces? I have mlx5, i40e and ice NICs 
> available for test.

There is no best setup I think.
You should check your environment with dpdk-testpmd.

> For mlx5 dpdk-devbind suggests that vfio-pci is compatible

That's interesting, we should take mlx4 and mlx5 as exceptions
in this script because they are bifurcated, i.e. no need of UIO or VFIO.
We should use the accurate info given by dpdk-pmdinfo.py

> whereas mlx5_core 
> is a kernel driver, but trying to run with vfio-pci leads to:
> 
> mlx5_common: No Verbs device matches PCI device 0000:01:00.0, are kernel 
> drivers loaded?
> 
> mlx5 seems to work correctly with MoonGen.

mlx5 is working with its own kernel driver.
The DPDK PMD is negotiating with the kernel driver to get the traffic.
The main benefit is that we can choose some flows to go directly in kernel,
and the rest being managed directly by DPDK, bypassing the kernel.