DPDK-实战之skeleton(basicfwd)

0x01 缘由

     继续学习DPDK示例，主要熟悉每个环节和设计理念，今天要学习的是一个相对简答的服务，仅仅从一个网口抓取数据包转发到另外一个网口，这样做双向转发，相当于桥的功能。其他基础业务都不做。

0x02 直接上源码分析

#include <stdint.h>#include <inttypes.h>#include <rte_eal.h>#include <rte_ethdev.h>#include <rte_cycles.h>#include <rte_lcore.h>#include <rte_mbuf.h>#define RX_RING_SIZE 128#define TX_RING_SIZE 512#define NUM_MBUFS 8191#define MBUF_CACHE_SIZE 250#define BURST_SIZE 32static const struct rte_eth_conf port_conf_default = {    .rxmode = { .max_rx_pkt_len = ETHER_MAX_LEN }};/* basicfwd.c: Basic DPDK skeleton forwarding example. *//* * 用全局默认的配置来初始化网口。在内存池中分配接收队列和发送队列。 */static inline intport_init(uint8_t port, struct rte_mempool *mbuf_pool){    struct rte_eth_conf port_conf = port_conf_default; //全部配置模式    const uint16_t rx_rings = 1, tx_rings = 1;   //每个网口队列多少，这里都为1    int retval;    uint16_t q;    if (port >= rte_eth_dev_count())  //检查网口编号        return -1;    /* 配置以太网设备 */    retval = rte_eth_dev_configure(port, rx_rings, tx_rings, &port_conf);    if (retval != 0)        return retval;    /* 为每个以太网网口分配和设置1个接收队列 */    for (q = 0; q < rx_rings; q++) {        retval = rte_eth_rx_queue_setup(port, q, RX_RING_SIZE,                rte_eth_dev_socket_id(port), NULL, mbuf_pool);        if (retval < 0)            return retval;    }    /* 为每个以太网网口分配和设置1个发送队列 */    for (q = 0; q < tx_rings; q++) {        retval = rte_eth_tx_queue_setup(port, q, TX_RING_SIZE,                rte_eth_dev_socket_id(port), NULL);        if (retval < 0)            return retval;    }    /* 开启以太网网口 */    retval = rte_eth_dev_start(port);    if (retval < 0)        return retval;    /* 打印网卡地址 MAC address. */    struct ether_addr addr;    rte_eth_macaddr_get(port, &addr);    printf("Port %u MAC: %02" PRIx8 " %02" PRIx8 " %02" PRIx8               " %02" PRIx8 " %02" PRIx8 " %02" PRIx8 "\n",            (unsigned)port,            addr.addr_bytes[0], addr.addr_bytes[1],            addr.addr_bytes[2], addr.addr_bytes[3],            addr.addr_bytes[4], addr.addr_bytes[5]);    /* 网口开启混杂模式 */    rte_eth_promiscuous_enable(port);    return 0;}/* * 一个线程处理一对网口，数据包一进一出。 */static __attribute__((noreturn)) voidlcore_main(void){    const uint8_t nb_ports = rte_eth_dev_count(); //网口数    uint8_t port;    /*     * 当有NUMA结构时，检查网口是否在同一个NUMA node节点上，只有在一个NUMA node上时轮询线程效率最好。     */    for (port = 0; port < nb_ports; port++)        if (rte_eth_dev_socket_id(port) > 0 &&                rte_eth_dev_socket_id(port) !=                        (int)rte_socket_id())            printf("WARNING, port %u is on remote NUMA node to "                    "polling thread.\n\tPerformance will "                    "not be optimal.\n", port);    printf("\nCore %u forwarding packets. [Ctrl+C to quit]\n",            rte_lcore_id());    /* 死循环处理数据包的搬运 */    for (;;) {        /*         * 一个端口接收包，然后直接转发到这对数据包上。         * 如 0 -> 1, 1 -> 0, 2 -> 3, 3 -> 2 等。         */        for (port = 0; port < nb_ports; port++) {            /* 从一个端口接收数据包 */            struct rte_mbuf *bufs[BURST_SIZE];            const uint16_t nb_rx = rte_eth_rx_burst(port, 0,                    bufs, BURST_SIZE);            if (unlikely(nb_rx == 0))                continue;            /* Send burst of TX packets, to second port of pair. */            const uint16_t nb_tx = rte_eth_tx_burst(port ^ 1, 0,                    bufs, nb_rx);            /* 释放没有发送的数据包。 */            if (unlikely(nb_tx < nb_rx)) {                uint16_t buf;                for (buf = nb_tx; buf < nb_rx; buf++)                    rte_pktmbuf_free(bufs[buf]);            }        }    }}/* * The main function, which does initialization and calls the per-lcore * functions. */intmain(int argc, char *argv[]){    struct rte_mempool *mbuf_pool; //使用内存池空间来容纳ring队列，接收和发送数据包    unsigned nb_ports;             //网卡数    uint8_t portid;                //网卡编号    /* Initialize the Environment Abstraction Layer (EAL). */    int ret = rte_eal_init(argc, argv);    if (ret < 0)        rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");    argc -= ret;    argv += ret;    /* 检查网卡是否为偶数 send/receive */    nb_ports = rte_eth_dev_count();    if (nb_ports < 2 || (nb_ports & 1))        rte_exit(EXIT_FAILURE, "Error: number of ports must be even\n");    /*  创建一个内存池来容纳mbufs。大小按网口多少来分配。相当于每个网口都要有一个接受和发送队列。*/    mbuf_pool = rte_pktmbuf_pool_create("MBUF_POOL", NUM_MBUFS * nb_ports,        MBUF_CACHE_SIZE, 0, RTE_MBUF_DEFAULT_BUF_SIZE, rte_socket_id());    if (mbuf_pool == NULL)        rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");    /* 初始化所有网口配置 */    for (portid = 0; portid < nb_ports; portid++)        if (port_init(portid, mbuf_pool) != 0)            rte_exit(EXIT_FAILURE, "Cannot init port %"PRIu8 "\n",                    portid);    if (rte_lcore_count() > 1)        printf("\nWARNING: Too many lcores enabled. Only 1 used.\n");    /* 仅仅用一个主线程调用，相当与一个线程处理一对网口的数据包。*/    lcore_main();    return 0;}

0x03 运行实例

[root@Huawei x86_64-native-linuxapp-gcc]# ./basicfwd -l 1 -n 4EAL: Detected lcore 0 as core 0 on socket 0EAL: Detected lcore 1 as core 1 on socket 0EAL: Detected lcore 2 as core 2 on socket 0EAL: Detected lcore 3 as core 3 on socket 0EAL: Detected lcore 4 as core 4 on socket 0EAL: Detected lcore 5 as core 5 on socket 0EAL: Detected lcore 6 as core 6 on socket 0EAL: Detected lcore 7 as core 7 on socket 0EAL: Detected lcore 8 as core 0 on socket 1EAL: Detected lcore 9 as core 1 on socket 1EAL: Detected lcore 10 as core 2 on socket 1EAL: Detected lcore 11 as core 3 on socket 1EAL: Detected lcore 12 as core 4 on socket 1EAL: Detected lcore 13 as core 5 on socket 1EAL: Detected lcore 14 as core 6 on socket 1EAL: Detected lcore 15 as core 7 on socket 1EAL: Detected lcore 16 as core 0 on socket 0EAL: Detected lcore 17 as core 1 on socket 0EAL: Detected lcore 18 as core 2 on socket 0EAL: Detected lcore 19 as core 3 on socket 0EAL: Detected lcore 20 as core 4 on socket 0EAL: Detected lcore 21 as core 5 on socket 0EAL: Detected lcore 22 as core 6 on socket 0EAL: Detected lcore 23 as core 7 on socket 0EAL: Detected lcore 24 as core 0 on socket 1EAL: Detected lcore 25 as core 1 on socket 1EAL: Detected lcore 26 as core 2 on socket 1EAL: Detected lcore 27 as core 3 on socket 1EAL: Detected lcore 28 as core 4 on socket 1EAL: Detected lcore 29 as core 5 on socket 1EAL: Detected lcore 30 as core 6 on socket 1EAL: Detected lcore 31 as core 7 on socket 1EAL: Support maximum 128 logical core(s) by configuration.EAL: Detected 32 lcore(s)EAL: Setting up physically contiguous memory...EAL: Ask a virtual area of 0x200000 bytesEAL: Virtual area found at 0x7f45f8000000 (size = 0x200000)EAL: Ask a virtual area of 0x7c00000 bytesEAL: Virtual area found at 0x7f45f0200000 (size = 0x7c00000)EAL: Ask a virtual area of 0x200000 bytesEAL: Virtual area found at 0x7f45efe00000 (size = 0x200000)EAL: Ask a virtual area of 0x7c00000 bytesEAL: Virtual area found at 0x7f45e8000000 (size = 0x7c00000)EAL: Ask a virtual area of 0x400000 bytesEAL: Virtual area found at 0x7f45e7a00000 (size = 0x400000)EAL: Requesting 64 pages of size 2MB from socket 0EAL: Requesting 64 pages of size 2MB from socket 1EAL: TSC frequency is ~2593994 KHzEAL: Master lcore 1 is ready (tid=f83f2880;cpuset=[1])EAL: PCI device 0000:04:00.0 on NUMA socket 0EAL:   probe driver: 8086:1521 rte_igb_pmdEAL:   Not managed by a supported kernel driver, skippedEAL: PCI device 0000:04:00.1 on NUMA socket 0EAL:   probe driver: 8086:1521 rte_igb_pmdEAL:   Not managed by a supported kernel driver, skippedEAL: PCI device 0000:04:00.2 on NUMA socket 0EAL:   probe driver: 8086:1521 rte_igb_pmdEAL:   PCI memory mapped at 0x7f45f7f00000EAL:   PCI memory mapped at 0x7f45f7efc000PMD: eth_igb_dev_init(): port_id 0 vendorID=0x8086 deviceID=0x1521EAL: PCI device 0000:04:00.3 on NUMA socket 0EAL:   probe driver: 8086:1521 rte_igb_pmdEAL:   PCI memory mapped at 0x7f45f0100000EAL:   PCI memory mapped at 0x7f45f8408000PMD: eth_igb_dev_init(): port_id 1 vendorID=0x8086 deviceID=0x1521EAL: PCI device 0000:05:00.0 on NUMA socket 0EAL:   probe driver: 8086:1522 rte_igb_pmdEAL:   Not managed by a supported kernel driver, skippedEAL: PCI device 0000:05:00.1 on NUMA socket 0EAL:   probe driver: 8086:1522 rte_igb_pmdEAL:   Not managed by a supported kernel driver, skippedEAL: PCI device 0000:05:00.2 on NUMA socket 0EAL:   probe driver: 8086:1522 rte_igb_pmdEAL:   Not managed by a supported kernel driver, skippedEAL: PCI device 0000:05:00.3 on NUMA socket 0EAL:   probe driver: 8086:1522 rte_igb_pmdEAL:   Not managed by a supported kernel driver, skippedPMD: eth_igb_rx_queue_setup(): sw_ring=0x7f45eff90fc0 hw_ring=0x7f45eff91400 dma_addr=0x67391400PMD: eth_igb_tx_queue_setup(): sw_ring=0x7f45eff7ee40 hw_ring=0x7f45eff80e80 dma_addr=0x67380e80PMD: eth_igb_start(): <<Port 0 MAC: a0 36 9f 03 a8 caPMD: eth_igb_rx_queue_setup(): sw_ring=0x7f45eff6e7c0 hw_ring=0x7f45eff6ec00 dma_addr=0x6736ec00PMD: eth_igb_tx_queue_setup(): sw_ring=0x7f45eff5c640 hw_ring=0x7f45eff5e680 dma_addr=0x6735e680PMD: eth_igb_start(): <<Port 1 MAC: a0 36 9f 03 a8 cbCore 1 forwarding packets. [Ctrl+C to quit]

0x04 总结

     思路比较简单，一个网口用两个缓存来缓存数据包，然后将数据包转发出去。此处用到了内存池结构。