白云区建材网站建设,成都网站建设培训学校,大型门户网站建设多少钱,绘画做动作的网站一、硬件卸载
硬件加速#xff0c;听名字就是明白是利用硬件加速。不太准确#xff0c;硬件加速其实更有效进行硬件的分工#xff0c;通过分工实现硬件的整体的效率的提升。其实硬件卸载就是硬件加速#xff0c;而实现硬件加速就需要进行功能卸载#xff0c;整体上就可以…一、硬件卸载
硬件加速听名字就是明白是利用硬件加速。不太准确硬件加速其实更有效进行硬件的分工通过分工实现硬件的整体的效率的提升。其实硬件卸载就是硬件加速而实现硬件加速就需要进行功能卸载整体上就可以叫做硬件卸载。 硬件卸载是指将某些任务或计算从计算机的主处理器 (CPU) 或一些软件功能转移到专用硬件组件例如网络接口卡 (NIC) 或图形处理单元 (GPU)的过程以提高系统性能和效率。而提到硬件卸载就不得提到软件定义网络 软件定义网络的主流的解决方案是从传统的包含专用硬件与控制平面相结合并提供选定的功能的交换机等单个设备转移到软件定义网络抽象出的控制平面、数据平面、管理平面三个不同的层。 第一层是管理层或管理平面。它包括像OpenStack这类应用所在的位置可以将一些配置应用于网络并将其用于虚拟化等领域。下一层是控制平面。最下面是数据平面。它由硬件例如白盒交换机和软件软件数据平面组成数据平面就是硬件卸载所在的地方。而软件定义网络一般是指通过某种技术将网络设备的控制面与数据面分离开形成灵活智能的网络。 软件数据平面是一个常用的术语用来描述处理网络数据包中用户数据的应用程序。DPDK数据平面开发套件这下明白了吧。
二、DPDK中的应用
DPDK主要是应对网络应用开发所以其主要和网卡打交道。DPDK为了支持网卡的硬件卸载需要提供相关的软件接口具体到实际情况网卡的硬件卸载可能是基于端口设置也可能是基于每个包设置使能。DPDK的mbuf可能是对应着一个包也可能多个mbuf对应着一个包这在mbuf中都有对应的标识来标定ol_flags。在“\dpdk-stable-19.11.14\lib\librte_mbuf\rte_mbuf_core.h”中有这些具体的定义如“PKT_RX_IP_CKSUM_NONE”等等。在相同文件夹下还有其它一些具体的宏定义大家也可以参考。 相关的硬件卸载功能主要是与实际的网卡的实现情况有关其主要有以下几种情况 1、硬件与更新功能卸载 它根据实际情况又可以分为 a.VLAN硬件卸载通过报文中Tag标识来进行标识控制。通过硬件卸载可以直接使用硬件操作而非软件利用CPU来进行操作减轻了CPU的负荷。 b.IEEE1588硬件卸载功能PTPPrecision Timing Protocol精准时间同步协议这个用硬件实现更便捷准确 c.IP TCP/UDP/SCTP checksum硬件卸载功能这个就不用说了硬件更快捷高效 d.Tunnel硬件卸载功能这个更好理解其实就是纯粹的协议的控制隧道就是一个安全通道一个专门的通道可以将不同的协议连接起来。类似于集装箱直接把原始包扔进去做负载。这种简单的封装其实更适合用硬件来完成。
2、分片功能卸载 分片说得有点高级其实也很好理解一个大城市不好管理划成一个个小片不就好管理了这就是分片。在网络通信中上层应用可能不会顾及底层的硬件和驱动的缓冲大小向下输出大量数据可实际的TCP的传输是有大小控制的这就需要将上层的数据分片成合适的大小。而这个分片的过程软件其实是不如硬件更容易实现。因为这种机械的固定的功能最是硬件的擅长的了。
3、组包功能卸载 组包其实就上面分片的逆操作。毕竟数据最终还是回流到上层应用必须保持数据的一致性呈现这就需要把在数据传输过程中的一系列辅助的动作恢复原样。这就和在网上购物一样可能是一个很小的物件但在实际传输中可能不断的被打包验证然后装箱运输。等到达目的地时再逆向操作最终原样送到购买者手中。
三、源码分析
在DPDK提供了对IEEE1588的功能支持
int
rte_eth_timesync_enable(uint16_t port_id)
{struct rte_eth_dev *dev;RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);dev rte_eth_devices[port_id];RTE_FUNC_PTR_OR_ERR_RET(*dev-dev_ops-timesync_enable, -ENOTSUP);return eth_err(port_id, (*dev-dev_ops-timesync_enable)(dev));
}int
rte_eth_timesync_disable(uint16_t port_id)
{struct rte_eth_dev *dev;RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);dev rte_eth_devices[port_id];RTE_FUNC_PTR_OR_ERR_RET(*dev-dev_ops-timesync_disable, -ENOTSUP);return eth_err(port_id, (*dev-dev_ops-timesync_disable)(dev));
}
int
rte_eth_timesync_read_rx_timestamp(uint16_t port_id, struct timespec *timestamp,uint32_t flags)
{struct rte_eth_dev *dev;RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);dev rte_eth_devices[port_id];RTE_FUNC_PTR_OR_ERR_RET(*dev-dev_ops-timesync_read_rx_timestamp, -ENOTSUP);return eth_err(port_id, (*dev-dev_ops-timesync_read_rx_timestamp)(dev, timestamp, flags));
}int
rte_eth_timesync_read_tx_timestamp(uint16_t port_id,struct timespec *timestamp)
{struct rte_eth_dev *dev;RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);dev rte_eth_devices[port_id];RTE_FUNC_PTR_OR_ERR_RET(*dev-dev_ops-timesync_read_tx_timestamp, -ENOTSUP);return eth_err(port_id, (*dev-dev_ops-timesync_read_tx_timestamp)(dev, timestamp));
}上面的代码很清晰就是使能和读取双向的时间戳。而在app/test-pmd中有计算checksum的方法
/* if possible, calculate the checksum of a packet in hw or sw,* depending on the testpmd command line configuration */
static uint64_t
process_inner_cksums(void *l3_hdr, const struct testpmd_offload_info *info,uint64_t tx_offloads)
{struct rte_ipv4_hdr *ipv4_hdr l3_hdr;struct rte_udp_hdr *udp_hdr;struct rte_tcp_hdr *tcp_hdr;struct rte_sctp_hdr *sctp_hdr;uint64_t ol_flags 0;uint32_t max_pkt_len, tso_segsz 0;/* ensure packet is large enough to require tso */if (!info-is_tunnel) {max_pkt_len info-l2_len info-l3_len info-l4_len info-tso_segsz;if (info-tso_segsz ! 0 info-pkt_len max_pkt_len)tso_segsz info-tso_segsz;} else {max_pkt_len info-outer_l2_len info-outer_l3_len info-l2_len info-l3_len info-l4_len info-tunnel_tso_segsz;if (info-tunnel_tso_segsz ! 0 info-pkt_len max_pkt_len)tso_segsz info-tunnel_tso_segsz;}if (info-ethertype _htons(RTE_ETHER_TYPE_IPV4)) {ipv4_hdr l3_hdr;ol_flags | PKT_TX_IPV4;if (info-l4_proto IPPROTO_TCP tso_segsz) {ol_flags | PKT_TX_IP_CKSUM;} else {if (tx_offloads DEV_TX_OFFLOAD_IPV4_CKSUM) {ol_flags | PKT_TX_IP_CKSUM;} else {ipv4_hdr-hdr_checksum 0;ipv4_hdr-hdr_checksum rte_ipv4_cksum(ipv4_hdr);}}} else if (info-ethertype _htons(RTE_ETHER_TYPE_IPV6))ol_flags | PKT_TX_IPV6;elsereturn 0; /* packet type not supported, nothing to do */if (info-l4_proto IPPROTO_UDP) {udp_hdr (struct rte_udp_hdr *)((char *)l3_hdr info-l3_len);/* do not recalculate udp cksum if it was 0 */if (udp_hdr-dgram_cksum ! 0) {if (tx_offloads DEV_TX_OFFLOAD_UDP_CKSUM) {ol_flags | PKT_TX_UDP_CKSUM;} else {udp_hdr-dgram_cksum 0;udp_hdr-dgram_cksum get_udptcp_checksum(l3_hdr, udp_hdr,info-ethertype);}}if (info-gso_enable)ol_flags | PKT_TX_UDP_SEG;} else if (info-l4_proto IPPROTO_TCP) {tcp_hdr (struct rte_tcp_hdr *)((char *)l3_hdr info-l3_len);if (tso_segsz)ol_flags | PKT_TX_TCP_SEG;else if (tx_offloads DEV_TX_OFFLOAD_TCP_CKSUM) {ol_flags | PKT_TX_TCP_CKSUM;} else {tcp_hdr-cksum 0;tcp_hdr-cksum get_udptcp_checksum(l3_hdr, tcp_hdr,info-ethertype);}if (info-gso_enable)ol_flags | PKT_TX_TCP_SEG;} else if (info-l4_proto IPPROTO_SCTP) {sctp_hdr (struct rte_sctp_hdr *)((char *)l3_hdr info-l3_len);/* sctp payload must be a multiple of 4 to be* offloaded */if ((tx_offloads DEV_TX_OFFLOAD_SCTP_CKSUM) ((ipv4_hdr-total_length 0x3) 0)) {ol_flags | PKT_TX_SCTP_CKSUM;} else {sctp_hdr-cksum 0;/* XXX implement CRC32c, example available in* RFC3309 */}}return ol_flags;
}看一下组包的支持
* Initializes Receive Unit.
*/
int __attribute__((cold))
ixgbe_dev_rx_init(struct rte_eth_dev *dev)
{struct ixgbe_hw *hw;struct ixgbe_rx_queue *rxq;uint64_t bus_addr;uint32_t rxctrl;uint32_t fctrl;uint32_t hlreg0;uint32_t maxfrs;uint32_t srrctl;uint32_t rdrxctl;uint32_t rxcsum;uint16_t buf_size;uint16_t i;struct rte_eth_rxmode *rx_conf dev-data-dev_conf.rxmode;int rc;PMD_INIT_FUNC_TRACE();hw IXGBE_DEV_PRIVATE_TO_HW(dev-data-dev_private);/** Make sure receives are disabled while setting* up the RX context (registers, descriptor rings, etc.).*/rxctrl IXGBE_READ_REG(hw, IXGBE_RXCTRL);IXGBE_WRITE_REG(hw, IXGBE_RXCTRL, rxctrl ~IXGBE_RXCTRL_RXEN);/* Enable receipt of broadcasted frames */fctrl IXGBE_READ_REG(hw, IXGBE_FCTRL);fctrl | IXGBE_FCTRL_BAM;fctrl | IXGBE_FCTRL_DPF;fctrl | IXGBE_FCTRL_PMCF;IXGBE_WRITE_REG(hw, IXGBE_FCTRL, fctrl);/** Configure CRC stripping, if any.*/hlreg0 IXGBE_READ_REG(hw, IXGBE_HLREG0);if (rx_conf-offloads DEV_RX_OFFLOAD_KEEP_CRC)hlreg0 ~IXGBE_HLREG0_RXCRCSTRP;elsehlreg0 | IXGBE_HLREG0_RXCRCSTRP;/** Configure jumbo frame support, if any.*/if (rx_conf-offloads DEV_RX_OFFLOAD_JUMBO_FRAME) {hlreg0 | IXGBE_HLREG0_JUMBOEN;maxfrs IXGBE_READ_REG(hw, IXGBE_MAXFRS);maxfrs 0x0000FFFF;maxfrs | (rx_conf-max_rx_pkt_len 16);IXGBE_WRITE_REG(hw, IXGBE_MAXFRS, maxfrs);} elsehlreg0 ~IXGBE_HLREG0_JUMBOEN;/** If loopback mode is configured, set LPBK bit.*/if (dev-data-dev_conf.lpbk_mode ! 0) {rc ixgbe_check_supported_loopback_mode(dev);if (rc 0) {PMD_INIT_LOG(ERR, Unsupported loopback mode);return rc;}hlreg0 | IXGBE_HLREG0_LPBK;} else {hlreg0 ~IXGBE_HLREG0_LPBK;}IXGBE_WRITE_REG(hw, IXGBE_HLREG0, hlreg0);/** Assume no header split and no VLAN strip support* on any Rx queue first .*/rx_conf-offloads ~DEV_RX_OFFLOAD_VLAN_STRIP;/* Setup RX queues */for (i 0; i dev-data-nb_rx_queues; i) {rxq dev-data-rx_queues[i];/** Reset crc_len in case it was changed after queue setup by a* call to configure.*/if (rx_conf-offloads DEV_RX_OFFLOAD_KEEP_CRC)rxq-crc_len RTE_ETHER_CRC_LEN;elserxq-crc_len 0;/* Setup the Base and Length of the Rx Descriptor Rings */bus_addr rxq-rx_ring_phys_addr;IXGBE_WRITE_REG(hw, IXGBE_RDBAL(rxq-reg_idx),(uint32_t)(bus_addr 0x00000000ffffffffULL));IXGBE_WRITE_REG(hw, IXGBE_RDBAH(rxq-reg_idx),(uint32_t)(bus_addr 32));IXGBE_WRITE_REG(hw, IXGBE_RDLEN(rxq-reg_idx),rxq-nb_rx_desc * sizeof(union ixgbe_adv_rx_desc));IXGBE_WRITE_REG(hw, IXGBE_RDH(rxq-reg_idx), 0);IXGBE_WRITE_REG(hw, IXGBE_RDT(rxq-reg_idx), 0);/* Configure the SRRCTL register */srrctl IXGBE_SRRCTL_DESCTYPE_ADV_ONEBUF;/* Set if packets are dropped when no descriptors available */if (rxq-drop_en)srrctl | IXGBE_SRRCTL_DROP_EN;/** Configure the RX buffer size in the BSIZEPACKET field of* the SRRCTL register of the queue.* The value is in 1 KB resolution. Valid values can be from* 1 KB to 16 KB.*/buf_size (uint16_t)(rte_pktmbuf_data_room_size(rxq-mb_pool) -RTE_PKTMBUF_HEADROOM);srrctl | ((buf_size IXGBE_SRRCTL_BSIZEPKT_SHIFT) IXGBE_SRRCTL_BSIZEPKT_MASK);IXGBE_WRITE_REG(hw, IXGBE_SRRCTL(rxq-reg_idx), srrctl);buf_size (uint16_t) ((srrctl IXGBE_SRRCTL_BSIZEPKT_MASK) IXGBE_SRRCTL_BSIZEPKT_SHIFT);/* It adds dual VLAN length for supporting dual VLAN */if (dev-data-dev_conf.rxmode.max_rx_pkt_len 2 * IXGBE_VLAN_TAG_SIZE buf_size)dev-data-scattered_rx 1;if (rxq-offloads DEV_RX_OFFLOAD_VLAN_STRIP)rx_conf-offloads | DEV_RX_OFFLOAD_VLAN_STRIP;}if (rx_conf-offloads DEV_RX_OFFLOAD_SCATTER)dev-data-scattered_rx 1;/** Device configured with multiple RX queues.*/ixgbe_dev_mq_rx_configure(dev);/** Setup the Checksum Register.* Disable Full-Packet Checksum which is mutually exclusive with RSS.* Enable IP/L4 checkum computation by hardware if requested to do so.*/rxcsum IXGBE_READ_REG(hw, IXGBE_RXCSUM);rxcsum | IXGBE_RXCSUM_PCSD;if (rx_conf-offloads DEV_RX_OFFLOAD_CHECKSUM)rxcsum | IXGBE_RXCSUM_IPPCSE;elserxcsum ~IXGBE_RXCSUM_IPPCSE;IXGBE_WRITE_REG(hw, IXGBE_RXCSUM, rxcsum);if (hw-mac.type ixgbe_mac_82599EB ||hw-mac.type ixgbe_mac_X540) {rdrxctl IXGBE_READ_REG(hw, IXGBE_RDRXCTL);if (rx_conf-offloads DEV_RX_OFFLOAD_KEEP_CRC)rdrxctl ~IXGBE_RDRXCTL_CRCSTRIP;elserdrxctl | IXGBE_RDRXCTL_CRCSTRIP;rdrxctl ~IXGBE_RDRXCTL_RSCFRSTSIZE;IXGBE_WRITE_REG(hw, IXGBE_RDRXCTL, rdrxctl);}rc ixgbe_set_rsc(dev);if (rc)return rc;ixgbe_set_rx_function(dev);return 0;
}
/*** ixgbe_set_rsc - configure RSC related port HW registers** Configures the ports RSC related registers according to the 4.6.7.2 chapter* of 82599 Spec (x540 configuration is virtually the same).** dev port handle** Returns 0 in case of success or a non-zero error code*/
static int
ixgbe_set_rsc(struct rte_eth_dev *dev)
{struct rte_eth_rxmode *rx_conf dev-data-dev_conf.rxmode;struct ixgbe_hw *hw IXGBE_DEV_PRIVATE_TO_HW(dev-data-dev_private);struct rte_eth_dev_info dev_info { 0 };bool rsc_capable false;uint16_t i;uint32_t rdrxctl;uint32_t rfctl;/* Sanity check */dev-dev_ops-dev_infos_get(dev, dev_info);if (dev_info.rx_offload_capa DEV_RX_OFFLOAD_TCP_LRO)rsc_capable true;if (!rsc_capable (rx_conf-offloads DEV_RX_OFFLOAD_TCP_LRO)) {PMD_INIT_LOG(CRIT, LRO is requested on HW that doesnt support it);return -EINVAL;}/* RSC global configuration (chapter 4.6.7.2.1 of 82599 Spec) */if ((rx_conf-offloads DEV_RX_OFFLOAD_KEEP_CRC) (rx_conf-offloads DEV_RX_OFFLOAD_TCP_LRO)) {/** According to chapter of 4.6.7.2.1 of the Spec Rev.* 3.0 RSC configuration requires HW CRC stripping being* enabled. If user requested both HW CRC stripping off* and RSC on - return an error.*/PMD_INIT_LOG(CRIT, LRO cant be enabled when HW CRC is disabled);return -EINVAL;}/* RFCTL configuration */rfctl IXGBE_READ_REG(hw, IXGBE_RFCTL);if ((rsc_capable) (rx_conf-offloads DEV_RX_OFFLOAD_TCP_LRO))rfctl ~IXGBE_RFCTL_RSC_DIS;elserfctl | IXGBE_RFCTL_RSC_DIS;/* disable NFS filtering */rfctl | IXGBE_RFCTL_NFSW_DIS | IXGBE_RFCTL_NFSR_DIS;IXGBE_WRITE_REG(hw, IXGBE_RFCTL, rfctl);/* If LRO hasnt been requested - we are done here. */if (!(rx_conf-offloads DEV_RX_OFFLOAD_TCP_LRO))return 0;/* Set RDRXCTL.RSCACKC bit */rdrxctl IXGBE_READ_REG(hw, IXGBE_RDRXCTL);rdrxctl | IXGBE_RDRXCTL_RSCACKC;IXGBE_WRITE_REG(hw, IXGBE_RDRXCTL, rdrxctl);/* Per-queue RSC configuration (chapter 4.6.7.2.2 of 82599 Spec) */for (i 0; i dev-data-nb_rx_queues; i) {struct ixgbe_rx_queue *rxq dev-data-rx_queues[i];uint32_t srrctl IXGBE_READ_REG(hw, IXGBE_SRRCTL(rxq-reg_idx));uint32_t rscctl IXGBE_READ_REG(hw, IXGBE_RSCCTL(rxq-reg_idx));uint32_t psrtype IXGBE_READ_REG(hw, IXGBE_PSRTYPE(rxq-reg_idx));uint32_t eitr IXGBE_READ_REG(hw, IXGBE_EITR(rxq-reg_idx));/** ixgbe PMD doesnt support header-split at the moment.** Following the 4.6.7.2.1 chapter of the 82599/x540* Spec if RSC is enabled the SRRCTL[n].BSIZEHEADER* should be configured even if header split is not* enabled. We will configure it 128 bytes following the* recommendation in the spec.*/srrctl ~IXGBE_SRRCTL_BSIZEHDR_MASK;srrctl | (128 IXGBE_SRRCTL_BSIZEHDRSIZE_SHIFT) IXGBE_SRRCTL_BSIZEHDR_MASK;/** TODO: Consider setting the Receive Descriptor Minimum* Threshold Size for an RSC case. This is not an obviously* beneficiary option but the one worth considering...*/rscctl | IXGBE_RSCCTL_RSCEN;rscctl | ixgbe_get_rscctl_maxdesc(rxq-mb_pool);psrtype | IXGBE_PSRTYPE_TCPHDR;/** RSC: Set ITR interval corresponding to 2K ints/s.** Full-sized RSC aggregations for a 10Gb/s link will* arrive at about 20K aggregation/s rate.** 2K inst/s rate will make only 10% of the* aggregations to be closed due to the interrupt timer* expiration for a streaming at wire-speed case.** For a sparse streaming case this setting will yield* at most 500us latency for a single RSC aggregation.*/eitr ~IXGBE_EITR_ITR_INT_MASK;eitr | IXGBE_EITR_INTERVAL_US(IXGBE_QUEUE_ITR_INTERVAL_DEFAULT);eitr | IXGBE_EITR_CNT_WDIS;IXGBE_WRITE_REG(hw, IXGBE_SRRCTL(rxq-reg_idx), srrctl);IXGBE_WRITE_REG(hw, IXGBE_RSCCTL(rxq-reg_idx), rscctl);IXGBE_WRITE_REG(hw, IXGBE_PSRTYPE(rxq-reg_idx), psrtype);IXGBE_WRITE_REG(hw, IXGBE_EITR(rxq-reg_idx), eitr);/** RSC requires the mapping of the queue to the* interrupt vector.*/ixgbe_set_ivar(dev, rxq-reg_idx, i, 0);}dev-data-lro 1;PMD_INIT_LOG(DEBUG, enabling LRO mode);return 0;
}ixgbe_set_rsc会对DEV_RX_OFFLOAD_TCP_LRO进行判断来决定是否组包这个LROLarge Receive Offload其实是RSCReceive Side Coalescing的另外一种描述方式。
四、总结
将整个转发的流程相关内容搞清楚后再去和代码匹配学习就会发现学习起来相对容易了很多。其实还是推荐大家多看一下DPDK的官方文档这样会更准确更清晰。但看官方文档有时对小白确实不是一个很友好的入门的方法。这就需要看一看别人学习和实践的心得了。 仁者见仁吧目的只有一个学会并能熟练使用DPDK。
