DPDK-22.11.2 [四] 官方basicfwd編譯運行講解

編譯安裝dpdk

綁定網卡驅動vfio

必須有兩個網口

配置LD_LIBRARY_PATH和PKG_CONFIG_PATH

編譯運行

basicfwd.c

這個程序是從一個網口獲取數據，然後發送到另一個網口，所以收發消息的代碼都有了，可以根據這個程序編寫自己的dpdk應用。

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2015 Intel Corporation
 */

#include <stdint.h>
#include <stdlib.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 1024
#define TX_RING_SIZE 1024

#define NUM_MBUFS 8191
#define MBUF_CACHE_SIZE 250
#define BURST_SIZE 32

/* basicfwd.c: Basic DPDK skeleton forwarding example. */

/*
 * Initializes a given port using global settings and with the RX buffers
 * coming from the mbuf_pool passed as a parameter.
 */

/* Main functional part of port initialization. 8< */
static inline int
port_init(uint16_t port, struct rte_mempool *mbuf_pool)
{
	struct rte_eth_conf port_conf;
	const uint16_t rx_rings = 1, tx_rings = 1;
	uint16_t nb_rxd = RX_RING_SIZE;
	uint16_t nb_txd = TX_RING_SIZE;
	int retval;
	uint16_t q;
	struct rte_eth_dev_info dev_info;
	struct rte_eth_txconf txconf;

	if (!rte_eth_dev_is_valid_port(port))
		return -1;

	memset(&port_conf, 0, sizeof(struct rte_eth_conf));

	retval = rte_eth_dev_info_get(port, &dev_info);
	if (retval != 0) {
		printf("Error during getting device (port %u) info: %s\n",
				port, strerror(-retval));
		return retval;
	}

	if (dev_info.tx_offload_capa & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE)
		port_conf.txmode.offloads |=
			RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE;

	/* Configure the Ethernet device. */
	retval = rte_eth_dev_configure(port, rx_rings, tx_rings, &port_conf);
	if (retval != 0)
		return retval;

	retval = rte_eth_dev_adjust_nb_rx_tx_desc(port, &nb_rxd, &nb_txd);
	if (retval != 0)
		return retval;

	/* Allocate and set up 1 RX queue per Ethernet port. */
	for (q = 0; q < rx_rings; q++) {
		retval = rte_eth_rx_queue_setup(port, q, nb_rxd,
				rte_eth_dev_socket_id(port), NULL, mbuf_pool);
		if (retval < 0)
			return retval;
	}

	txconf = dev_info.default_txconf;
	txconf.offloads = port_conf.txmode.offloads;
	/* Allocate and set up 1 TX queue per Ethernet port. */
	for (q = 0; q < tx_rings; q++) {
		retval = rte_eth_tx_queue_setup(port, q, nb_txd,
				rte_eth_dev_socket_id(port), &txconf);
		if (retval < 0)
			return retval;
	}

	/* Starting Ethernet port. 8< */
	retval = rte_eth_dev_start(port);
	/* >8 End of starting of ethernet port. */
	if (retval < 0)
		return retval;

	/* Display the port MAC address. */
	struct rte_ether_addr addr;
	retval = rte_eth_macaddr_get(port, &addr);
	if (retval != 0)
		return retval;

	printf("Port %u MAC: %02" PRIx8 " %02" PRIx8 " %02" PRIx8
			   " %02" PRIx8 " %02" PRIx8 " %02" PRIx8 "\n",
			port, RTE_ETHER_ADDR_BYTES(&addr));

	/* Enable RX in promiscuous mode for the Ethernet device. */
	retval = rte_eth_promiscuous_enable(port);
	/* End of setting RX port in promiscuous mode. */
	if (retval != 0)
		return retval;

	return 0;
}
/* >8 End of main functional part of port initialization. */

/*
 * The lcore main. This is the main thread that does the work, reading from
 * an input port and writing to an output port.
 */

 /* Basic forwarding application lcore. 8< */
static __rte_noreturn void
lcore_main(void)
{
	uint16_t port;

	/*
	 * Check that the port is on the same NUMA node as the polling thread
	 * for best performance.
	 */
	RTE_ETH_FOREACH_DEV(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());

	/* Main work of application loop. 8< */
	for (;;) {
		/*
		 * Receive packets on a port and forward them on the paired
		 * port. The mapping is 0 -> 1, 1 -> 0, 2 -> 3, 3 -> 2, etc.
		 */
		RTE_ETH_FOREACH_DEV(port) {

			/* Get burst of RX packets, from first port of pair. */
			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);

			/* Free any unsent packets. */
			if (unlikely(nb_tx < nb_rx)) {
				uint16_t buf;
				for (buf = nb_tx; buf < nb_rx; buf++)
					rte_pktmbuf_free(bufs[buf]);
			}
		}
	}
	/* >8 End of loop. */
}
/* >8 End Basic forwarding application lcore. */

/*
 * The main function, which does initialization and calls the per-lcore
 * functions.
 */
int
main(int argc, char *argv[])
{
	struct rte_mempool *mbuf_pool;
	unsigned nb_ports;
	uint16_t portid;

	/* Initializion the Environment Abstraction Layer (EAL). 8< */
	int ret = rte_eal_init(argc, argv);
	if (ret < 0)
		rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");
	/* >8 End of initialization the Environment Abstraction Layer (EAL). */

	argc -= ret;
	argv += ret;

	/* Check that there is an even number of ports to send/receive on. */
	nb_ports = rte_eth_dev_count_avail();
	if (nb_ports < 2 || (nb_ports & 1))
		rte_exit(EXIT_FAILURE, "Error: number of ports must be even\n");

	/* Creates a new mempool in memory to hold the mbufs. */

	/* Allocates mempool to hold the mbufs. 8< */
	mbuf_pool = rte_pktmbuf_pool_create("MBUF_POOL", NUM_MBUFS * nb_ports,
		MBUF_CACHE_SIZE, 0, RTE_MBUF_DEFAULT_BUF_SIZE, rte_socket_id());
	/* >8 End of allocating mempool to hold mbuf. */

	if (mbuf_pool == NULL)
		rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");

	/* Initializing all ports. 8< */
	RTE_ETH_FOREACH_DEV(portid)
		if (port_init(portid, mbuf_pool) != 0)
			rte_exit(EXIT_FAILURE, "Cannot init port %"PRIu16 "\n",
					portid);
	/* >8 End of initializing all ports. */

	if (rte_lcore_count() > 1)
		printf("\nWARNING: Too many lcores enabled. Only 1 used.\n");

	/* Call lcore_main on the main core only. Called on single lcore. 8< */
	lcore_main();
	/* >8 End of called on single lcore. */

	/* clean up the EAL */
	rte_eal_cleanup();

	return 0;
}

int ret = rte_eal_init(argc, argv);

rte_eal_init()
int rte_eal_init 	( 	int  	argc,
		char **  	argv 
	) 	

Initialize the Environment Abstraction Layer (EAL).

This function is to be executed on the MAIN lcore only, as soon as possible in the application's main() function. It puts the WORKER lcores in the WAIT state.

初始化程序，需要在主線程調用，儘可能優先調用。

argc和argv與c語言main函數的參數一致，argc表示參數個數，argv是參數列表。

支持的參數

官方文檔給定了rte_eal_init的參數說明，比如常見的：

-l <core list>

List of cores to run on

The argument format is <c1>[-c2][,c3[-c4],...] where c1, c2, etc are core indexes between 0 and 128.

具體可以參考官方資料 http://doc.dpdk.org/guides-22.11/linux_gsg/linux_eal_parameters.html

返回值表示rte_eal_init使用了幾個參數，後續通過

	argc -= ret;
	argv += ret;

跳過使用過的參數，然後解析自己程序需要的參數。

所以dpdk中的示例代碼大部分都有這套邏輯，並且官方有說明，rte_eal_init需要的參數要放在前面，後面跟--，然後是自己的參數。rte_eal_init解析到--就會結束，返回解析了多少參數，然後跳過對應的參數，再解析自己的參數。

http://doc.dpdk.org/api-22.11/index.html
http://doc.dpdk.org/guides-22.11/index.html