Re: IPv4 flows per queue on top of RSS for ixgbe and i40e drivers

[Pavel Vazharov <freakpv@gmail.com>]

On Wed, Feb 5, 2025 at 6:50 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> On Wed, 5 Feb 2025 18:21:33 +0200
> Pavel Vazharov <freakpv@gmail.com> wrote:
>
> > Hi there,
> >
> > We have a proxy application on top of DPDK where we use a symmetric
> > RSS key to receive the packets for a given connection in both
> > directions on a single queue. In addition to that, we've few IPv4
> > addresses where we need to receive their traffic on particular queues.
> > We use the rte flows functionality with RTE_FLOW_ACTION_TYPE_QUEUE to
> > achieve that and it seemed to work with the DPDK ixgbe driver.
> > However, today we tried the same application on top of DPDK i40e
> > driver and this setup doesn't seem to work there. It prints the
> > following errors:
> > `i40e_flow_add_del_fdir_filter(): Conflict with existing flow director rules!`
> > It seems that the i40e driver doesn't allow adding flow rules on top
> > of the already set RSS.
> >
> > Can somebody suggest a way to achieve what we need with i40e: to use a
> > symmetric RSS key for most of the traffic but to redirect the traffic
> > for a few specific IPv4 addresses to particular queues?
> >
> > Thanks,
> > Pavel.
>
> If you are mixing RSS and rte_flow the results are not well defined.
> Many drivers treat all active queues (including those used by rte_flow)
> as candidates for RSS.
>
> If you want to mix, the the safe way is:
>         - don't enable RSS in the device config (rx_mode)
>         - define an rte_flow rule with RTE_FLOW_ACTION_TYPE_RSS
>           with a match all
>         - define a rte_flow rule with RTE_FLOW_ACTION_TYPE_QUEUE
>           that matches the IP
> and set rule priorities so that specific IP rule matches before
> the match all.
Thank you for this idea. I'll give it a try.

> You still maybe at risk of hardware quirks and driver incompatibilities
> which is part of the problem with rte_flow.