RE: [PATCH v8 1/3] ethdev: introduce protocol header based buffer split

["Ding, Xuan" <xuan.ding@intel.com>]

Hi Andrew,

> -----Original Message-----
> From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> Sent: Thursday, June 2, 2022 9:21 PM
> To: Wu, WenxuanX <wenxuanx.wu@intel.com>; thomas@monjalon.net; Li,
> Xiaoyun <xiaoyun.li@intel.com>; ferruh.yigit@xilinx.com; Singh, Aman Deep
> <aman.deep.singh@intel.com>; dev@dpdk.org; Zhang, Yuying
> <yuying.zhang@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>;
> jerinjacobk@gmail.com
> Cc: stephen@networkplumber.org; Ding, Xuan <xuan.ding@intel.com>;
> Wang, YuanX <yuanx.wang@intel.com>; Ray Kinsella <mdr@ashroe.eu>
> Subject: Re: [PATCH v8 1/3] ethdev: introduce protocol header based buffer
> split
> 
> There are two v8 1/3 patches in my mailbox. Which one is the right one?

Yes, you are right, the second one is the latest one, sorry for the inconvenience.

Thanks,
Xuan

> 
> On 6/1/22 16:50, wenxuanx.wu@intel.com wrote:
> > From: Wenxuan Wu <wenxuanx.wu@intel.com>
> >
> > 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 a arbitrarily variable length
> > in Rx packet segment, it is almost impossible to pass a fixed protocol
> header to PMD.
> > 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 happens 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, PMD will split the ingress packets into multiple
> segments.
> >
> > 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 */
> >          uint32_t proto_hdr; /* inner/outer L2/L3/L4 protocol header,
> > 			       configures "split point" */
> >      };
> >
> > Both inner and outer L2/L3/L4 level protocol header split can be supported.
> > Corresponding protocol header capability is RTE_PTYPE_L2_ETHER,
> > RTE_PTYPE_L3_IPV4, RTE_PTYPE_L3_IPV6, RTE_PTYPE_L4_TCP,
> > RTE_PTYPE_L4_UDP, RTE_PTYPE_L4_SCTP, RTE_PTYPE_INNER_L2_ETHER,
> > RTE_PTYPE_INNER_L3_IPV4, RTE_PTYPE_INNER_L3_IPV6,
> > RTE_PTYPE_INNER_L4_TCP, RTE_PTYPE_INNER_L4_UDP,
> RTE_PTYPE_INNER_L4_SCTP.
> >
> > For example, let's suppose we configured the Rx queue with the
> > following segments:
> >      seg0 - pool0, proto_hdr0=RTE_PTYPE_L3_IPV4, off0=2B
> >      seg1 - pool1, proto_hdr1=RTE_PTYPE_L4_UDP, off1=128B
> >      seg2 - pool2, off1=0B
> >
> > The packet consists of MAC_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
> >
> > Now buffet 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 should not be configured.
> > For protocol header based buffer split, the mp, offset, proto_hdr
> > field in Rx packet segment should be configured, while the length
> > field should not be configured.
> >
> > The split limitations imposed by underlying PMD 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: Xuan Ding <xuan.ding@intel.com>
> > Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> > Signed-off-by: Wenxuan Wu <wenxuanx.wu@intel.com>
> > Reviewed-by: Qi Zhang <qi.z.zhang@intel.com>
> > Acked-by: Ray Kinsella <mdr@ashroe.eu>
> 
> [snip]