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 6:53 PM Pavel Vazharov <freakpv@gmail.com> wrote:
>
> 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.
The proposed setup worked for NICs with e1000 and ixgb drivers but
with i40e driver it returns error "Not support priority.".
I poke through the code of the DPDK i40e driver and the
`i40e_flow_parse_attr` is called for every type of flow - rss, fdir,
etc.
And inside this function, there is this piece of code:
    /* Not supported */
    if (attr->priority) {
        rte_flow_error_set(error, EINVAL,
                   RTE_FLOW_ERROR_TYPE_ATTR_PRIORITY,
                   attr, "Not support priority.");
        return -rte_errno;
    }
So, it seems to me that the driver don't support any flows with priority.
>
> > You still maybe at risk of hardware quirks and driver incompatibilities
> > which is part of the problem with rte_flow.