Re: [dpdk-users] Basic doubt on testpmd app working on x86_64 linux host

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 7 Jul 2021 18:03:24 +0530
Ashish Mishra <ashishm@mvista.com> wrote:

> Hi Members ,
> 
> I am trying to learn DPDK on my laptop for which I installed
> dpdk-stable-19.11.8  +
> testpmd on x86_64 linux host
> ( will move to latest DPDK once i have some idea )
> 
> When I tried testpmd , I had below gaps in my understanding / doubts .
> If member's can please provide some pointer on below point :
> 
> 1) NUMA socket -1
>    I am trying to understand DPDK using testpmd.
>    When i execute testpmd , i am getting the below message .
>    Are these normal message or something is wrong in my setup
>         EAL: PCI device 0000:00:1f.6 on NUMA socket -1
>         EAL:   Invalid NUMA socket, default to 0

Ignore this, it means your system only has a single numa node, so then
kernel reports all devices as attached to that node.

> 2) What is the memory-channels parameter  usage ,which is being passed to
> testpmd.

It is is an optimization to spread memory.
If you want to figure out what is best for your machine, use dmidecode to
look at memory banks, and count how many channels.

> 
> 3) Do we have any logical loopback mode in DPDK?
>    So that we can try tx & rx logically without being dependent on hardware
> ports

There are various ring pseudo-device that might be useful for this.
Or TAP on a dummy network device.

> 4) How to know if the ethernet should be binded to IGB-UIO or VFIO module
>    As of now , i try both & continue with which doesn't throw errors.

There are some flags but no script I know uses them.

> I am reading the Documentation but felt short for these aspects
> & hence thought to check with the community for any pointers / guidance.
> 
> Apologies if these are vary basic in nature as i am just starting with DPDK
> environment
> 
> Thanks ,
> Ashish