The af_packet pmd driver binds to a raw socket and allows sending and receiving of packets through the kernel.
Since commit [1], the kernel strips the vlan tags early in __netif_receive_skb_core(), so we receive untagged packets while running with the af_packet pmd. Luckily for us, the skb vlan-related fields are still populated from the stripped vlan tags, so we end up having all the information that we need in the mbuf. Having the pmd driver support DEV_RX_OFFLOAD_VLAN_STRIP allows the application to control the desired vlan stripping behavior, until we have a way to describe offloads that can't be disabled by pmd drivers. This patch will cause a change in the default way that the af_packet pmd treats received vlan-tagged frames. While previously, the application was required to check the PKT_RX_VLAN_STRIPPED flag, after this patch, the pmd will re-insert the vlan tag transparently to the user, unless the DEV_RX_OFFLOAD_VLAN_STRIP is enabled in rxmode.offloads. I've attempted a preliminary benchmark to understand if the change could cause a sizable performance hit. Setup: Two virtual machines running on top of an ESXi hypervisor Tx: DPDK app (running on top of vmxnet3 PMD) Rx: af_packet (running on top of a kernel vmxnet3 interface) Packet size :68 (packet contains a vlan tag) Rates: Tx - 1.419 Mpps Rx (without vlan insertion) - 1227636 pps Rx (with vlan insertion) - 1220081 pps At a first glance, we don't seem to have a large degradation in terms of packet rate. [1] https://github.com/torvalds/linux/commit/bcc6d47903612c3861201cc3a866fb604f26b8b2 Signed-off-by: Tudor Cornea <tudor.cor...@gmail.com> --- v4: * Updated the af_packet documentation v3: * Updated release note and documentation * Updated commit with performance measurements v2: * Added DEV_RX_OFFLOAD_VLAN_STRIP to rxmode->offloads --- doc/guides/nics/af_packet.rst | 5 +++++ doc/guides/rel_notes/release_21_11.rst | 4 ++++ drivers/net/af_packet/rte_eth_af_packet.c | 12 ++++++++++++ 3 files changed, 21 insertions(+) diff --git a/doc/guides/nics/af_packet.rst b/doc/guides/nics/af_packet.rst index efd6f1c..c87310b 100644 --- a/doc/guides/nics/af_packet.rst +++ b/doc/guides/nics/af_packet.rst @@ -65,3 +65,8 @@ framecnt=512): .. code-block:: console --vdev=eth_af_packet0,iface=tap0,blocksz=4096,framesz=2048,framecnt=512,qpairs=1,qdisc_bypass=0 + +Features and Limitations of the af_packet PMD +--------------------------------------------- + +Af_packet PMD now works with VLAN's on Linux diff --git a/doc/guides/rel_notes/release_21_11.rst b/doc/guides/rel_notes/release_21_11.rst index ad7c1af..095fd5b 100644 --- a/doc/guides/rel_notes/release_21_11.rst +++ b/doc/guides/rel_notes/release_21_11.rst @@ -66,6 +66,10 @@ New Features * Added rte_flow support for dual VLAN insert and strip actions. +* **Updated af_packet ethdev driver.** + + * Added DEV_RX_OFFLOAD_VLAN_STRIP capability. + * **Updated Marvell cnxk crypto PMD.** * Added AES-CBC SHA1-HMAC support in lookaside protocol (IPsec) for CN10K. diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c index b73b211..5ed9dd6 100644 --- a/drivers/net/af_packet/rte_eth_af_packet.c +++ b/drivers/net/af_packet/rte_eth_af_packet.c @@ -48,6 +48,7 @@ struct pkt_rx_queue { struct rte_mempool *mb_pool; uint16_t in_port; + uint8_t vlan_strip; volatile unsigned long rx_pkts; volatile unsigned long rx_bytes; @@ -78,6 +79,7 @@ struct pmd_internals { struct pkt_rx_queue *rx_queue; struct pkt_tx_queue *tx_queue; + uint8_t vlan_strip; }; static const char *valid_arguments[] = { @@ -148,6 +150,9 @@ eth_af_packet_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) if (ppd->tp_status & TP_STATUS_VLAN_VALID) { mbuf->vlan_tci = ppd->tp_vlan_tci; mbuf->ol_flags |= (PKT_RX_VLAN | PKT_RX_VLAN_STRIPPED); + + if (!pkt_q->vlan_strip && rte_vlan_insert(&mbuf)) + PMD_LOG(ERR, "Failed to reinsert VLAN tag"); } /* release incoming frame and advance ring buffer */ @@ -302,6 +307,11 @@ eth_dev_stop(struct rte_eth_dev *dev) static int eth_dev_configure(struct rte_eth_dev *dev __rte_unused) { + struct rte_eth_conf *dev_conf = &dev->data->dev_conf; + const struct rte_eth_rxmode *rxmode = &dev_conf->rxmode; + struct pmd_internals *internals = dev->data->dev_private; + + internals->vlan_strip = !!(rxmode->offloads & DEV_RX_OFFLOAD_VLAN_STRIP); return 0; } @@ -318,6 +328,7 @@ eth_dev_info(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info) dev_info->min_rx_bufsize = 0; dev_info->tx_offload_capa = DEV_TX_OFFLOAD_MULTI_SEGS | DEV_TX_OFFLOAD_VLAN_INSERT; + dev_info->rx_offload_capa = DEV_RX_OFFLOAD_VLAN_STRIP; return 0; } @@ -448,6 +459,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev, dev->data->rx_queues[rx_queue_id] = pkt_q; pkt_q->in_port = dev->data->port_id; + pkt_q->vlan_strip = internals->vlan_strip; return 0; } -- 2.7.4
