> > As discussed in that thread: > > http://dpdk.org/ml/archives/dev/2015-September/023603.html > > Different NIC models depending on HW offload requested might impose different > requirements on packets to be TX-ed in terms of: > > - Max number of fragments per packet allowed > - Max number of fragments per TSO segments > - The way pseudo-header checksum should be pre-calculated > - L3/L4 header fields filling > - etc. > > > MOTIVATION: > ----------- > > 1) Some work cannot (and didn't should) be done in rte_eth_tx_burst. > However, this work is sometimes required, and now, it's an > application issue. > > 2) Different hardware may have different requirements for TX offloads, > other subset can be supported and so on. > > 3) Some parameters (e.g. number of segments in ixgbe driver) may hung > device. These parameters may be vary for different devices. > > For example i40e HW allows 8 fragments per packet, but that is after > TSO segmentation. While ixgbe has a 38-fragment pre-TSO limit. > > 4) Fields in packet may require different initialization (like e.g. will > require pseudo-header checksum precalculation, sometimes in a > different way depending on packet type, and so on). Now application > needs to care about it. > > 5) Using additional API (rte_eth_tx_prep) before rte_eth_tx_burst let to > prepare packet burst in acceptable form for specific device. > > 6) Some additional checks may be done in debug mode keeping tx_burst > implementation clean. > > > PROPOSAL: > --------- > > To help user to deal with all these varieties we propose to: > > 1) Introduce rte_eth_tx_prep() function to do necessary preparations of > packet burst to be safely transmitted on device for desired HW > offloads (set/reset checksum field according to the hardware > requirements) and check HW constraints (number of segments per > packet, etc). > > While the limitations and requirements may differ for devices, it > requires to extend rte_eth_dev structure with new function pointer > "tx_pkt_prep" which can be implemented in the driver to prepare and > verify packets, in devices specific way, before burst, what should to > prevent application to send malformed packets. > > 2) Also new fields will be introduced in rte_eth_desc_lim: > nb_seg_max and nb_mtu_seg_max, providing an information about max > segments in TSO and non-TSO packets acceptable by device. > > This information is useful for application to not create/limit > malicious packet. > > > APPLICATION (CASE OF USE): > -------------------------- > > 1) Application should to initialize burst of packets to send, set > required tx offload flags and required fields, like l2_len, l3_len, > l4_len, and tso_segsz > > 2) Application passes burst to the rte_eth_tx_prep to check conditions > required to send packets through the NIC. > > 3) The result of rte_eth_tx_prep can be used to send valid packets > and/or restore invalid if function fails. > > e.g. > > for (i = 0; i < nb_pkts; i++) { > > /* initialize or process packet */ > > bufs[i]->tso_segsz = 800; > bufs[i]->ol_flags = PKT_TX_TCP_SEG | PKT_TX_IPV4 > | PKT_TX_IP_CKSUM; > bufs[i]->l2_len = sizeof(struct ether_hdr); > bufs[i]->l3_len = sizeof(struct ipv4_hdr); > bufs[i]->l4_len = sizeof(struct tcp_hdr); > } > > /* Prepare burst of TX packets */ > nb_prep = rte_eth_tx_prep(port, 0, bufs, nb_pkts); > > if (nb_prep < nb_pkts) { > printf("tx_prep failed\n"); > > /* nb_prep indicates here first invalid packet. rte_eth_tx_prep > * can be used on remaining packets to find another ones. > */ > > } > > /* Send burst of TX packets */ > nb_tx = rte_eth_tx_burst(port, 0, bufs, nb_prep); > > /* Free any unsent packets. */ > > > v5 changes: > - rebased csum engine modification > - added information to the csum engine about performance tests > - some performance improvements > > v4 changes: > - tx_prep is now set to default behavior (NULL) for simple/vector path > in fm10k, i40e and ixgbe drivers to increase performance, when > Tx offloads are not intentionally available > > v3 changes: > - reworked csum testpmd engine instead adding new one, > - fixed checksum initialization procedure to include also outer > checksum offloads, > - some minor formattings and optimalizations > > v2 changes: > - rte_eth_tx_prep() returns number of packets when device doesn't > support tx_prep functionality, > - introduced CONFIG_RTE_ETHDEV_TX_PREP allowing to turn off tx_prep > > > Tomasz Kulasek (6): > ethdev: add Tx preparation > e1000: add Tx preparation > fm10k: add Tx preparation > i40e: add Tx preparation > ixgbe: add Tx preparation > testpmd: use Tx preparation in csum engine > > app/test-pmd/csumonly.c | 36 ++++------ > config/common_base | 1 + > drivers/net/e1000/e1000_ethdev.h | 11 +++ > drivers/net/e1000/em_ethdev.c | 5 +- > drivers/net/e1000/em_rxtx.c | 48 ++++++++++++- > drivers/net/e1000/igb_ethdev.c | 4 ++ > drivers/net/e1000/igb_rxtx.c | 52 ++++++++++++++- > drivers/net/fm10k/fm10k.h | 6 ++ > drivers/net/fm10k/fm10k_ethdev.c | 5 ++ > drivers/net/fm10k/fm10k_rxtx.c | 50 +++++++++++++- > drivers/net/i40e/i40e_ethdev.c | 3 + > drivers/net/i40e/i40e_rxtx.c | 72 +++++++++++++++++++- > drivers/net/i40e/i40e_rxtx.h | 8 +++ > drivers/net/ixgbe/ixgbe_ethdev.c | 3 + > drivers/net/ixgbe/ixgbe_ethdev.h | 5 +- > drivers/net/ixgbe/ixgbe_rxtx.c | 58 +++++++++++++++- > drivers/net/ixgbe/ixgbe_rxtx.h | 2 + > lib/librte_ether/rte_ethdev.h | 85 +++++++++++++++++++++++ > lib/librte_mbuf/rte_mbuf.h | 9 +++ > lib/librte_net/Makefile | 3 +- > lib/librte_net/rte_pkt.h | 137 > ++++++++++++++++++++++++++++++++++++++ > 21 files changed, 572 insertions(+), 31 deletions(-) > create mode 100644 lib/librte_net/rte_pkt.h > > --
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com> > 1.7.9.5
