rte-flow: unmatched ingress traffic default action

[Robin Jarry]

Hi Ori, all,

>From what I can read in the docs in the "Isolated Mode"[1] section:

> The general expectation for ingress traffic is that flow rules process
> it first; the remaining unmatched or pass-through traffic usually ends
> up in a queue (with or without RSS, locally or in some sub-device
> instance) depending on the global configuration settings of a port.

[1]: https://doc.dpdk.org/guides/prog_guide/rte_flow.html#flow-isolated-mode

Should I read "general expectation" as a simple recommendation or is it
a requirement from the RTE flow API?

I realize that this eventually will depend on each driver, firmware
and/or hardware. However, would it be reasonable to rely on such
a behaviour to implement preemptive queue redirection prior to regular
RSS?

For the sake of argument, let's say I have 3 RX queues configured with
an RSS redirection table set as follows:

    0 1 0 1 0 1 0 1 0 1 ..... 1 0 1

And I configure a single flow:

    struct rte_flow_error error;
    struct rte_flow *flow;

    flow = rte_flow_create(
        port_id,
        (const struct rte_flow_attr){ .ingress = 1 },
        (const struct rte_flow_item []) {
            {
                .type = RTE_FLOW_ITEM_TYPE_ETH,
                .spec = &(const struct rte_flow_item_eth){
                    .type = htons(0x1234),
                },
                .mask = &(const struct rte_flow_item_eth){
                    .type = htons(0xffff),
                },
            },
            { .type = RTE_FLOW_ITEM_TYPE_END },
        },
        (const struct rte_flow_action actions[]){
            {
                .type = RTE_FLOW_ACTION_TYPE_QUEUE,
                .conf = &(const struct rte_flow_action_queue) {
                    .index = 2,
                },
            },
            { .type = RTE_FLOW_ACTION_TYPE_END },
        },
        &error,
    );

Can I expect *all* ingress traffic *not* matching ether_type=0x1234 to
be redirected to queues 0 and 1 following the default RSS algorithm?

If folks from NIC vendors could comment on their own implementation, it
would be much appreciated.

Thanks in advance.

-- 
Robin Jarry
Principal Software Engineer
Red Hat