RE: Issue in testpmd when using RSS Flows with Mellanox NICs

[Dariusz Sosnowski <dsosnowski@nvidia.com>]

Hi,

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Wednesday, July 31, 2024 15:02
> To: Alex Chapman <alex.chapman@arm.com>
> Cc: dev@dpdk.org; Luca.Vizzarro@arm.com; Paul.Szczepanek@arm.com; Dariusz
> Sosnowski <dsosnowski@nvidia.com>; Slava Ovsiienko
> <viacheslavo@nvidia.com>; Bing Zhao <bingz@nvidia.com>; Ori Kam
> <orika@nvidia.com>; Suanming Mou <suanmingm@nvidia.com>; Matan Azrad
> <matan@nvidia.com>
> 
> Hello,
> 
> 31/07/2024 14:55, Alex Chapman:
> > Hello maintainers,
> 
> Do not hesitate to read the file MAINTAINERS to place the appropriate Cc list.
> Adding mlx5 maintainers.
> 
> 
> > I am currently facing issues when creating RSS flows using testpmd.
> > When using the following flow on an intel NIC, it works as expected,
> > using the reta table to redirect ipv4-udp packets to the correct queue.
> >
> >         flow create 0 ingress pattern eth / ipv4 / udp / end actions
> > rss types ipv4-udp end queues end func toeplitz / end
> >
> > However when executing the same command on a Mellanox NIC, the
> > following error occurs.
> >
> >      Caught PMD error type 15 (action configuration): No queues
> > configured: Invalid argument
> >
> > This error can be resolved by manually specifying the queues used:
> >
> >      flow create 0 ingress pattern eth / ipv4 / udp / end actions rss
> > types ipv4-udp end queues 0 1 2 3 4 5 6 7 8 end func toeplitz / end
> >
> > However the packets are not placed into their expected queues using
> > the reta table.

Currently mlx5 PMD requires that array of Rx queues is provided with RSS flow action.
There's no support right now for default set of queues on mlx5 PMD side.

"queues" parameter of RSS flow action takes Rx queue indices directly, not redirection table indices,
so when RSS hash is calculated during processing of that action,
then the queue is selected as:

	queues[hash % nb_of_queues]

> >
> > When looking through the Generic flow API guide under RSS
> > (https://doc.dpdk.org/guides/prog_guide/rte_flow.html), the attribute
> > queues does not exist.
> >  From my understanding this seems to be a mistake, as the attribute
> > "queue" does exist with the definition "queue indices to use"
> > However when attempting to use this attribute I get the error "Bad
> > arguments"

Yes, that's a mistake and we should fix that.

> > If anyone is able to shed some light on the use of RSS in flows, that
> > would be greatly appreciated.
> >
> > Thanks,
> > Alex
> 
> 

Best regards,
Dariusz Sosnowski