Re: [PATCH 1/2] usertools/rss: add driver abstractions

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 23 Oct 2023 10:07:11 +0200
Robin Jarry <rjarry@redhat.com> wrote:

> +class DriverInfo:
> +    def __init__(self, key: bytes = None, reta_size: int = None):
> +        self.__key = key
> +        self.__reta_size = reta_size
> +
> +    def rss_key(self) -> bytes:
> +        return self.__key
> +
> +    def reta_size(self, num_queues: int) -> int:
> +        return self.__reta_size
> +
> +
> +class MlxDriverInfo(DriverInfo):
> +    def rss_key(self) -> bytes:
> +        return bytes(
> +            (
> +                # fmt: off
> +                # rss_hash_default_key, see drivers/net/mlx5/mlx5_rxq.c
> +                0x2c, 0xc6, 0x81, 0xd1, 0x5b, 0xdb, 0xf4, 0xf7,
> +                0xfc, 0xa2, 0x83, 0x19, 0xdb, 0x1a, 0x3e, 0x94,
> +                0x6b, 0x9e, 0x38, 0xd9, 0x2c, 0x9c, 0x03, 0xd1,
> +                0xad, 0x99, 0x44, 0xa7, 0xd9, 0x56, 0x3d, 0x59,
> +                0x06, 0x3c, 0x25, 0xf3, 0xfc, 0x1f, 0xdc, 0x2a,
> +                # fmt: on
> +            )
> +        )
> +
> +    def reta_size(self, num_queues: int) -> int:
> +        if num_queues & (num_queues - 1) == 0:
> +            # If the requested number of RX queues is power of two,
> +            # use a table of this size.
> +            return num_queues
> +        # otherwise, use the maximum table size
> +        return 512
> +
> +
> +DEFAULT_DRIVERS = {
> +    "intel": DriverInfo(
> +        key=bytes(
> +            (
> +                # fmt: off
> +                # rss_intel_key, see drivers/net/ixgbe/ixgbe_rxtx.c
> +                0x6d, 0x5a, 0x56, 0xda, 0x25, 0x5b, 0x0e, 0xc2,
> +                0x41, 0x67, 0x25, 0x3d, 0x43, 0xa3, 0x8f, 0xb0,
> +                0xd0, 0xca, 0x2b, 0xcb, 0xae, 0x7b, 0x30, 0xb4,
> +                0x77, 0xcb, 0x2d, 0xa3, 0x80, 0x30, 0xf2, 0x0c,
> +                0x6a, 0x42, 0xb7, 0x3b, 0xbe, 0xac, 0x01, 0xfa,
> +                # fmt: on
> +            )
> +        ),
> +        reta_size=128,
> +    ),
> +    "mlx": MlxDriverInfo(),
> +    "i40e": DriverInfo(
> +        key=bytes(
> +            (
> +                # fmt: off
> +                # rss_key_default, see drivers/net/i40e/i40e_ethdev.c
> +                # i40e is the only driver that takes 52 bytes keys
> +                0x44, 0x39, 0x79, 0x6b, 0xb5, 0x4c, 0x50, 0x23,
> +                0xb6, 0x75, 0xea, 0x5b, 0x12, 0x4f, 0x9f, 0x30,
> +                0xb8, 0xa2, 0xc0, 0x3d, 0xdf, 0xdc, 0x4d, 0x02,
> +                0xa0, 0x8c, 0x9b, 0x33, 0x4a, 0xf6, 0x4a, 0x4c,
> +                0x05, 0xc6, 0xfa, 0x34, 0x39, 0x58, 0xd8, 0x55,
> +                0x7d, 0x99, 0x58, 0x3a, 0xe1, 0x38, 0xc9, 0x2e,
> +                0x81, 0x15, 0x03, 0x66,
> +                # fmt: on
> +            )
> +        ),
> +        reta_size=512,
> +    ),
>  }

The tool should not need to have driver specific tables like this.
DPDK is already riddled with enough driver specific quirks..

That shows a flaw in the rss design, which should have been fixed.
I should have seen this in the earlier versions, would have rejected the patch.