Re: [dpdk-dev] [PATCH v5 0/3] i40e VXLAN TX checksum rework

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jijiang Liu
> Sent: Tuesday, December 02, 2014 3:06 PM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH v5 0/3] i40e VXLAN TX checksum rework
> 
> We have got some feedback about backward compatibility of VXLAN TX checksum offload API with 1G/10G NIC after the i40e VXLAN
> TX checksum codes were applied, so we have to rework the APIs on i40e, including the changes of mbuf, i40e PMD and csum forward
> engine.
> 
> The main changes in mbuf are as follows, in place of removing PKT_TX_VXLAN_CKSUM, we introduce 4 new flags:
> PKT_TX_OUTER_IP_CKSUM, PKT_TX_OUTER_IPV4, PKT_TX_OUTER_IPV6 and PKT_TX_UDP_TUNNEL_PKT. Replace the inner_l2_len
> and the inner_l3_len field with the outer_l2_len and outer_l3_len field.
> 
> Let's use a few examples to demonstrate how to use these new flags and existing flags in rte_mbuf.h
> Let say we have a tunnel packet: eth_hdr_out/ipv4_hdr_out/udp_hdr_out/vxlan_hdr/ehtr_hdr_in/ipv4_hdr_in/tcp_hdr_in. There
> could be several scenarios:
> 
> A) User requests HW offload for ipv4_hdr_out checksum.
> He doesn't care is it a tunnelled packet or not. So he sets:
> 
> mb->l2_len = eth_hdr_out;
> mb->l3_len = ipv4_hdr_out;
> mb->ol_flags |= PKT_TX_IPV4_CSUM;
> 
> B) User is aware that it is a tunnelled packet and requests HW offload for ipv4_hdr_in and tcp_hdr_in *only*.
> He doesn't care about outer IP checksum offload. In that case, for FVL  he has 2 choices:
>    1. Treat that packet as a 'proper' tunnelled packet, and fill all the fields:
>      mb->l2_len = udp_hdr_out + vxlan_hdr +eth_hdr_in;
>      mb->l3_len = ipv4_hdr_in;
>      mb->outer_l2_len = eth_hdr_out;
>      mb->outer_l3_len = ipv4_hdr_out;
>      mb->ol_flags |= PKT_TX_UDP_TUNNEL_PKT | PKT_TX_IP_CKSUM |  PKT_TX_TCP_CKSUM;
> 
>    2. As user doesn't care about outer IP hdr checksum, he can treat everything before ipv4_hdr_in as L2 header.
>    So he knows, that it is a tunnelled packet, but makes HW to treat it as ordinary (non-tunnelled) packet:
>      mb->l2_len = eth_hdr_out + ipv4_hdr_out + udp_hdr_out + vxlan_hdr + ehtr_hdr_in;
>      mb->l3_len = ipv4_hdr_in;
>      mb->ol_flags |= PKT_TX_IP_CKSUM |  PKT_TX_TCP_CKSUM;
> 
> i40e PMD will support both B.1 and B.2, but ixgbe/igb/em PMD supports only B.2.
> if HW supports both - it will be up to user app which method to choose.
> tespmd will support both methods, and it should be configurable by user which approach to use (cmdline parameter).
> So the user can try/test both methods and select an appropriate for him.
> 
> C) User knows that is a tunnelled packet, and wants HW offload for all 3 checksums:  outer IP hdr checksum, inner IP checksum, inner
> TCP checksum.
> Then he has to setup all TX checksum fields:
>      mb->l2_len =  udp_hdr_out + vxlan_hdr +eth_hdr_in;;
>      mb->l3_len = ipv4_hdr_in;
>      mb->outer_l2_len = eth_hdr_out;
>      mb->outer_l3_len = ipv4_hdr_out;
>      mb->ol_flags |= PKT_TX_OUT_IP_CKSUM  | PKT_TX_UDP_TUNNEL_PKT | PKT_TX_IP_CKSUM |  PKT_TX_TCP_CKSUM;
> 
> Change notes:
> v2 changes:
>      remove PKT_TX_IP_CKSUM alias.
>      add PKT_TX_OUT_IP_CKSUM and PKT_TX_OUTER_IPV6 in rte_get_tx_ol_flag_name.
>      spliting mbuf changes into two patches.
>      fix MACLEN caculation issue in i40e driver
>      fix some issues in csumonly.c
>      change cover letter.
> v3 changes:
>      fix MACLEN caculation issue in i40e driver when non-tunneling packet
> v4 changes:
>      reorganize patches to avoid compilation to be broken between patches.
>      remove l4_tun_len from mbuf structure.
>      add PKT_TX_OUTER_IPV4 to indicate no IP checksum offload requirement for tunneling packet.
>      change i40e PMD and csum engine due to above changes.
> 
> v5 changes:
>      according to Konstantin's comments, optimize process_outer_cksums() in order to avoid setting PKT_TX_OUTER_IPV4 flags for the
> case when user didn't enable TESTPMD_TX_OFFLOAD_VXLAN_CKSUM
> 
> Jijiang Liu (3):
>   Redefine PKT_TX_IPV4, PKT_TX_IPV6 and PKT_TX_VLAN_PKT;
>   Replace PKT_TX_VXLAN_CKSUM with PKT_TX_UDP_TUNNEL_PKT, and add 3 TX flags, which are PKT_TX_OUTER_IP_CKSUM,
> PKT_TX_OUTER_IPV4 and PKT_TX_OUTER_IPV6,and rework csum forward engine and i40e pmd due to these changes;
>   Replace the inner_l2_len and the inner_l3_len field with the outer_l2_len and outer_l3_len field, and rework csum forward engine
> and i40e pmd due to  these changes;
> 
>  app/test-pmd/csumonly.c         |   69 ++++++++++++++++++++++----------------
>  lib/librte_mbuf/rte_mbuf.c      |    7 +++-
>  lib/librte_mbuf/rte_mbuf.h      |   25 +++++++++----
>  lib/librte_pmd_i40e/i40e_rxtx.c |   44 +++++++++++++------------
>  4 files changed, 86 insertions(+), 59 deletions(-)
> 
> --
> 1.7.7.6

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>