RE: [PATCH v5 2/4] ethdev: introduce protocol hdr based buffer split

["Wang, YuanX" <yuanx.wang@intel.com>]

Hi Andrew,

Did you get a chance to review this patch? Please let me know your thoughts on it.

Regards,
Yuan

> -----Original Message-----
> From: Wang, YuanX <yuanx.wang@intel.com>
> Sent: Monday, September 26, 2022 5:41 PM
> To: dev@dpdk.org; Thomas Monjalon <thomas@monjalon.net>; Ferruh Yigit
> <ferruh.yigit@xilinx.com>; Andrew Rybchenko
> <andrew.rybchenko@oktetlabs.ru>
> Cc: mdr@ashroe.eu; Li, Xiaoyun <xiaoyun.li@intel.com>; Singh, Aman Deep
> <aman.deep.singh@intel.com>; Zhang, Yuying <yuying.zhang@intel.com>;
> Zhang, Qi Z <qi.z.zhang@intel.com>; Yang, Qiming <qiming.yang@intel.com>;
> jerinjacobk@gmail.com; viacheslavo@nvidia.com;
> stephen@networkplumber.org; Ding, Xuan <xuan.ding@intel.com>;
> hpothula@marvell.com; Tang, Yaqi <yaqi.tang@intel.com>; Wang, YuanX
> <yuanx.wang@intel.com>; Wenxuan Wu <wenxuanx.wu@intel.com>
> Subject: [PATCH v5 2/4] ethdev: introduce protocol hdr based buffer split
> 
> Currently, Rx buffer split supports length based split. With Rx queue offload
> RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT enabled and Rx packet segment
> configured, PMD will be able to split the received packets into multiple
> segments.
> 
> However, length based buffer split is not suitable for NICs that do split based
> on protocol headers. Given an arbitrarily variable length in Rx packet
> segment, it is almost impossible to pass a fixed protocol header to driver.
> Besides, the existence of tunneling results in the composition of a packet is
> various, which makes the situation even worse.
> 
> This patch extends current buffer split to support protocol header based
> buffer split. A new proto_hdr field is introduced in the reserved field of
> rte_eth_rxseg_split structure to specify protocol header. The proto_hdr field
> defines the split position of packet, splitting will always happen after the
> protocol header defined in the Rx packet segment. When Rx queue offload
> RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT is enabled and corresponding
> protocol header is configured, driver will split the ingress packets into
> multiple segments.
> 
> Examples for proto_hdr field defines:
> To split after ETH-IPV4-UDP, it should be defined as RTE_PTYPE_L2_ETHER |
> RTE_PTYPE_L3_IPV4_EXT_UNKNOWN | RTE_PTYPE_L4_UDP
> 
> For inner ETH-IPV4-UDP, it should be defined as
> RTE_PTYPE_TUNNEL_GRENAT | RTE_PTYPE_INNER_L2_ETHER |
> RTE_PTYPE_INNER_L3_IPV4_EXT_UNKNOWN | RTE_PTYPE_INNER_L4_UDP
> 
> struct rte_eth_rxseg_split {
>         struct rte_mempool *mp; /* memory pools to allocate segment from */
>         uint16_t length; /* segment maximal data length,
>                             configures split point */
>         uint16_t offset; /* data offset from beginning
>                             of mbuf data buffer */
>         /**
> 	 * Proto_hdr defines a bit mask of the protocol sequence as
>          * RTE_PTYPE_*, configures split point. The last RTE_PTYPE*
>          * in the mask indicates the split position.
> 	 * For non-tunneling packets, the complete protocol sequence
>          * should be defined.
> 	 * For tunneling packets, for simplicity, only the tunnel and
>          * inner protocol sequence should be defined.
> 	 */
>         uint32_t proto_hdr;
> };
> 
> If protocol header split can be supported by a PMD, the
> rte_eth_buffer_split_get_supported_hdr_ptypes function can be use to
> obtain a list of these protocol headers.
> 
> For example, let's suppose we configured the Rx queue with the following
> segments:
>         seg0 - pool0, proto_hdr0=RTE_PTYPE_L2_ETHER | RTE_PTYPE_L3_IPV4,
>                off0=2B
>         seg1 - pool1, proto_hdr1=RTE_PTYPE_L2_ETHER | RTE_PTYPE_L3_IPV4
>                | RTE_PTYPE_L4_UDP, off1=128B
>         seg2 - pool2, off1=0B
> 
> The packet consists of ETH_IPV4_UDP_PAYLOAD will be split like
> following:
>         seg0 - ipv4 header @ RTE_PKTMBUF_HEADROOM + 2 in mbuf from pool0
>         seg1 - udp header @ 128 in mbuf from pool1
>         seg2 - payload @ 0 in mbuf from pool2
> 
> Note: NIC will only do split when the packets exactly match all the protocol
> headers in the segments. For example, if ARP packets received with above
> config, the NIC won't do split for ARP packets since it does not contains ipv4
> header and udp header. These packets will be put into the last valid
> mempool, with zero offset.
> 
> Now buffer split can be configured in two modes. For length based buffer
> split, the mp, length, offset field in Rx packet segment should be configured,
> while the proto_hdr field will be ignored.
> For protocol header based buffer split, the mp, offset, proto_hdr field in Rx
> packet segment should be configured, while the length field will be ignored.
> 
> The split limitations imposed by underlying driver is reported in the
> rte_eth_dev_info->rx_seg_capa field. The memory attributes for the split
> parts may differ either, dpdk memory and external memory, respectively.
> 
> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> Signed-off-by: Wenxuan Wu <wenxuanx.wu@intel.com>
> ---
>  doc/guides/rel_notes/release_22_11.rst |  7 +++
>  lib/ethdev/rte_ethdev.c                | 74 ++++++++++++++++++++++----
>  lib/ethdev/rte_ethdev.h                | 29 +++++++++-
>  3 files changed, 98 insertions(+), 12 deletions(-)
> 
> diff --git a/doc/guides/rel_notes/release_22_11.rst
> b/doc/guides/rel_notes/release_22_11.rst
> index 8e5bdde46a..cce1f6e50c 100644
> --- a/doc/guides/rel_notes/release_22_11.rst
> +++ b/doc/guides/rel_notes/release_22_11.rst
> @@ -64,6 +64,13 @@ New Features
>    Added ``rte_eth_buffer_split_get_supported_hdr_ptypes()``, to get
> supported
>    header protocols of a PMD to split.
> 
> +* **Added protocol header based buffer split.**
> +
> +  Ethdev: The ``reserved`` field in the ``rte_eth_rxseg_split``
> + structure is  replaced with ``proto_hdr`` to support protocol header based
> buffer split.
> +  User can choose length or protocol header to configure buffer split
> + according to NIC's capability.
> +
> 
>  Removed Items
>  -------------
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c index
> 1f0a7f8f3f..27ec19faed 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -1649,9 +1649,10 @@ rte_eth_dev_is_removed(uint16_t port_id)  }
> 
>  static int
> -rte_eth_rx_queue_check_split(const struct rte_eth_rxseg_split *rx_seg,
> -			     uint16_t n_seg, uint32_t *mbp_buf_size,
> -			     const struct rte_eth_dev_info *dev_info)
> +rte_eth_rx_queue_check_split(uint16_t port_id,
> +			const struct rte_eth_rxseg_split *rx_seg,
> +			uint16_t n_seg, uint32_t *mbp_buf_size,
> +			const struct rte_eth_dev_info *dev_info)
>  {
>  	const struct rte_eth_rxseg_capa *seg_capa = &dev_info-
> >rx_seg_capa;
>  	struct rte_mempool *mp_first;
> @@ -1674,6 +1675,7 @@ rte_eth_rx_queue_check_split(const struct
> rte_eth_rxseg_split *rx_seg,
>  		struct rte_mempool *mpl = rx_seg[seg_idx].mp;
>  		uint32_t length = rx_seg[seg_idx].length;
>  		uint32_t offset = rx_seg[seg_idx].offset;
> +		uint32_t proto_hdr = rx_seg[seg_idx].proto_hdr;
> 
>  		if (mpl == NULL) {
>  			RTE_ETHDEV_LOG(ERR, "null mempool pointer\n");
> @@ -1707,13 +1709,63 @@ rte_eth_rx_queue_check_split(const struct
> rte_eth_rxseg_split *rx_seg,
>  		}
>  		offset += seg_idx != 0 ? 0 : RTE_PKTMBUF_HEADROOM;
>  		*mbp_buf_size = rte_pktmbuf_data_room_size(mpl);
> -		length = length != 0 ? length : *mbp_buf_size;
> -		if (*mbp_buf_size < length + offset) {
> -			RTE_ETHDEV_LOG(ERR,
> -				       "%s mbuf_data_room_size %u < %u
> (segment length=%u + segment offset=%u)\n",
> -				       mpl->name, *mbp_buf_size,
> -				       length + offset, length, offset);
> -			return -EINVAL;
> +
> +		if (proto_hdr > 0) {
> +			/* Split based on protocol headers. */
> +
> +			/* skip the payload */
> +			if (proto_hdr == RTE_PTYPE_ALL_MASK)
> +				continue;
> +
> +			int ptype_cnt;
> +
> +			ptype_cnt =
> rte_eth_buffer_split_get_supported_hdr_ptypes(port_id, NULL, 0);
> +			if (ptype_cnt <= 0) {
> +				RTE_ETHDEV_LOG(ERR,
> +					"Port %u failed to supported buffer
> split header protocols\n",
> +					port_id);
> +				return -EINVAL;
> +			}
> +
> +			uint32_t ptypes[ptype_cnt];
> +			int i;
> +
> +			ptype_cnt =
> rte_eth_buffer_split_get_supported_hdr_ptypes(port_id,
> +
> 	ptypes, ptype_cnt);
> +			if (ptype_cnt < 0) {
> +				RTE_ETHDEV_LOG(ERR,
> +					"Port %u failed to supported buffer
> split header protocols\n",
> +					port_id);
> +				return -EINVAL;
> +			}
> +
> +			for (i = 0; i < ptype_cnt; i++)
> +				if (ptypes[i] == proto_hdr)
> +					break;
> +			if (i == ptype_cnt) {
> +				RTE_ETHDEV_LOG(ERR,
> +					"Requested Rx split header protocols
> 0x%x is not supported.\n",
> +					proto_hdr);
> +				return -EINVAL;
> +			}
> +
> +			if (*mbp_buf_size < offset) {
> +				RTE_ETHDEV_LOG(ERR,
> +						"%s
> mbuf_data_room_size %u < %u segment offset)\n",
> +						mpl->name, *mbp_buf_size,
> +						offset);
> +				return -EINVAL;
> +			}
> +		} else {
> +			/* Split at fixed length. */
> +			length = length != 0 ? length : *mbp_buf_size;
> +			if (*mbp_buf_size < length + offset) {
> +				RTE_ETHDEV_LOG(ERR,
> +					"%s mbuf_data_room_size %u < %u
> (segment length=%u + segment offset=%u)\n",
> +					mpl->name, *mbp_buf_size,
> +					length + offset, length, offset);
> +				return -EINVAL;
> +			}
>  		}
>  	}
>  	return 0;
> @@ -1793,7 +1845,7 @@ rte_eth_rx_queue_setup(uint16_t port_id,
> uint16_t rx_queue_id,
>  		n_seg = rx_conf->rx_nseg;
> 
>  		if (rx_conf->offloads &
> RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT) {
> -			ret = rte_eth_rx_queue_check_split(rx_seg, n_seg,
> +			ret = rte_eth_rx_queue_check_split(port_id, rx_seg,
> n_seg,
>  							   &mbp_buf_size,
>  							   &dev_info);
>  			if (ret != 0)
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h index
> c440e3863a..ba7c11f735 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -994,6 +994,9 @@ struct rte_eth_txmode {
>   *   specified in the first array element, the second buffer, from the
>   *   pool in the second element, and so on.
>   *
> + * - The proto_hdrs in the elements define the split position of
> + *   received packets.
> + *
>   * - The offsets from the segment description elements specify
>   *   the data offset from the buffer beginning except the first mbuf.
>   *   The first segment offset is added with RTE_PKTMBUF_HEADROOM.
> @@ -1015,12 +1018,36 @@ struct rte_eth_txmode {
>   *     - pool from the last valid element
>   *     - the buffer size from this pool
>   *     - zero offset
> + *
> + * - Length based buffer split:
> + *     - mp, length, offset should be configured.
> + *     - The proto_hdr field will be ignored.
> + *
> + * - Protocol header based buffer split:
> + *     - mp, offset, proto_hdr should be configured.
> + *     - The length field will be ignored.
> + *
> + * - For Protocol header based buffer split, if the received packets
> + *   don't exactly match all protocol headers in the elements, packets
> + *   will not be split.
> + *   These packets will be put into:
> + *     - pool from the last valid element
> + *     - the buffer size from this pool
> + *     - zero offset
>   */
>  struct rte_eth_rxseg_split {
>  	struct rte_mempool *mp; /**< Memory pool to allocate segment
> from. */
>  	uint16_t length; /**< Segment data length, configures split point. */
>  	uint16_t offset; /**< Data offset from beginning of mbuf data buffer.
> */
> -	uint32_t reserved; /**< Reserved field. */
> +	/**
> +	 * Proto_hdr defines a bit mask of the protocol sequence as
> RTE_PTYPE_*,
> +	 * configures split point. The last RTE_PTYPE* in the mask indicates
> the
> +	 * split position.
> +	 * For non-tunneling packets, the complete protocol sequence
> should be defined.
> +	 * For tunneling packets, for simplicity, only the tunnel and inner
> +	 * protocol sequence should be defined.
> +	 */
> +	uint32_t proto_hdr;
>  };
> 
>  /**
> --
> 2.25.1