发烧友实测 | i.MX8MP 编译DPDK源码实现rte_ring无锁环

作者｜donatello1996

来源 | 电子发烧友

题图｜飞凌嵌入式

rte_ring是一个用CAS实现的无锁FIFO环形队列，支持多消费者/生产者同时出入队列，常用于多线程/多进程之间的通信。具体原理可以查看DPDK官方文档或者阅读源码，本文采用的硬件板卡为飞凌嵌入式OKMX8MP-C开发板，系统版本Linux5.4.70+Qt5.15.0，主要介绍通过编译DPDK源码实现rte_ring无锁环队列进程间通信。

下面就跟着小编一起了解下。

一、内核编译

下载并解压飞凌厂商提供的iMX8MP内核源码压缩包分卷：

在虚拟机中合并压缩分卷并解压得出内核源码包文件夹OK8MP-linux-kernel，将文件夹使用tar打包并复制到TF卡文件系统中解压：

找到内核源码中的配置文件OK8MP-C_defconfig：

这个就是make选项，使用

make OK8MP-C_defconfig

指令即可配置编译选项：

make -j4

开始编译：

注意开始编译前需要安装常用软件：

apt install bison bc flex

增量编译完毕：

二、DPDK编译

接下来就可以下载DPDK并运行rte_ring无锁环队列Demo应用，需要从

https://www.dpdk.org/

官网中下载DPDK 19.11.10 (LTS)长期支持版本：

在根目录下的mk/文件夹下找到名为rte_vars.mk设置文件，找到环境变量RTE_KERNELDIR，修改为上述的内核源码路径：

RTE_KERNELDIR ?= /home/OK8MP-linux-kernel/

进入usertools文件夹，找到dpdk-setup.sh脚本并运行

选择8，ARM64-armv8a-linuxapp-gcc，

这个选项会使dpdk的gcc交叉编译链生成适用于armv8a处理器的外部库，外部库中有kmod和lib等ko文件和so文件，是用于第三方程序开发和运行的：

使用指令

insmod /home/dpdk-stable-19.11.10/arm64-armv8a-linuxapp-gcc/kmod/igb_uio.ko

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加载igb_uio.ko驱动文件，这是进行dpdk开发必备的步骤：

然后是使用dpdk-devbind.py脚本手动进行hugepage大页内存绑定，此处为numa方式：

此举会将/mnt/huge文件mount成hugepage映射文件，并实实在在地占用内存空间：

三、rte_ring无锁环队列

准备工作完成，我们接下来可以进行rte_ring无锁环队列Demo代码的编写，但是在编写之前，需要对无锁环队列有一个基本的认识：https://blog.csdn.net/chen98765432101/article/details/69367633

无论是dpdk第三方开发的rte_ring还是Linux内核中本就存在的无锁环队列，其基本原理类似，在一条分配好的队列型内存空间中，读写方式为FIFO（先进先出），读和写的动作分别有两个进程或两个线程进行，写进程不断往地址自增的内存位置写入数据，读进程不断读取地址自增的内存位置的数据，当写位置的内存地址已为队列中内存的最高值时，需要释放队列中内存地址最低值的空间供写进程继续写，方式仍与上一周期相同（不断往地址自增的内存位置写入数据），释放过程需要保证对末尾内存地址空间的锁定与解锁，避免读写过程出错。而不同的是，Linux内核中的无锁环队列，地址管理和读写控制均由内核进行，而dpdk的rte_ring则由dpdk内部的控制器进行，因为dpdk这一模块完整地接管了所分配内存空间的管理权，是直接绕过Linux内核进行管理的，内核也无权访问dpdk控制器的具体管理细节。

编写无锁环队列两个进程的Demo，先写Primary进程：

#include #include #include #include #include #include #include #include #include #include 
#include #include 
#define RTE_LOGTYPE_APP RTE_LOGTYPE_USER1
static const char *_MSG_POOL = "MSG_POOL";static const char *_SEC_2_PRI = "SEC_2_PRI";static const char *_PRI_2_SEC = "PRI_2_SEC";static const char *_PRI_2_THI = "PRI_2_THI";
struct rte_ring *send_ring, *recv_ring , *send_ring_third;struct rte_mempool *message_pool;volatile int quit = 0;
static void * lcore_recv(void *arg){        unsigned lcore_id = rte_lcore_id();
        printf("Starting core %u\n", lcore_id);        while (!quit){                void *msg;                if (rte_ring_dequeue(recv_ring, &msg) < 0)                {                        usleep(5);                        continue;                }                printf("lcore_id = %d Received '%s'\n" , lcore_id , (char *)msg);                rte_mempool_put(message_pool , msg);        }
        return 0;}
int string_size = 100;int elt_size = 128;pthread_t id1;
int main(int argc, char **argv){        const unsigned flags = 0;        const unsigned ring_size = 64;        const unsigned pool_size = 1024;        const unsigned pool_cache = 32;        const unsigned priv_data_sz = 0;
        int ret;        unsigned lcore_id;
        ret = rte_eal_init(argc, argv);        if (ret < 0)                rte_exit(EXIT_FAILURE, "Cannot init EAL\n");
        send_ring = rte_ring_create(_PRI_2_SEC, ring_size, rte_socket_id(), flags);        recv_ring = rte_ring_create(_SEC_2_PRI, ring_size, rte_socket_id(), flags);        send_ring_third = rte_ring_create(_PRI_2_THI, ring_size, rte_socket_id(), flags);        message_pool = rte_mempool_create(_MSG_POOL, pool_size,                        elt_size, pool_cache, priv_data_sz,                        NULL, NULL, NULL, NULL,                        rte_socket_id(), flags);
        if (send_ring == NULL)                rte_exit(EXIT_FAILURE, "Problem getting sending ring\n");
        if (recv_ring == NULL)                rte_exit(EXIT_FAILURE, "Problem getting receiving ring\n");
        if (send_ring_third == NULL)                rte_exit(EXIT_FAILURE, "Problem getting send_ring_third\n");
        if (message_pool == NULL)                rte_exit(EXIT_FAILURE, "Problem getting message pool\n");
        pthread_create(&id1 , NULL , lcore_recv , NULL);        while(1)        {                void *msg = NULL;                if (rte_mempool_get(message_pool, &msg) < 0)                        continue;
                snprintf((char *)msg, string_size, "%s", "primary to secondary");                if (rte_ring_enqueue(send_ring , msg) < 0)                 {                        rte_mempool_put(message_pool, msg);                }
                if (rte_mempool_get(message_pool, &msg) < 0)                        continue;
                snprintf((char *)msg, string_size, "%s", "primary to third");                if (rte_ring_enqueue(send_ring_third , msg) < 0)                 {                        rte_mempool_put(message_pool, msg);                }
                sleep(1);        }
        return 0;}

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注意在Makefile文件里面要关闭WERROR相关编译选项：

#   BSD LICENSE##   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.#   All rights reserved.##   Redistribution and use in source and binary forms, with or without#   modification, are permitted provided that the following conditions#   are met:##     * Redistributions of source code must retain the above copyright#       notice, this list of conditions and the following disclaimer.#     * Redistributions in binary form must reproduce the above copyright#       notice, this list of conditions and the following disclaimer in#       the documentation and/or other materials provided with the#       distribution.#     * Neither the name of Intel Corporation nor the names of its#       contributors may be used to endorse or promote products derived#       from this software without specific prior written permission.##   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
ifeq ($(RTE_SDK),)$(error "Please define RTE_SDK environment variable")endif
# Default target, can be overridden by command line or environmentRTE_TARGET ?= arm64-armv8a-linuxapp-gcc
include $(RTE_SDK)/mk/rte.vars.mk
# binary nameAPP = rte_ring_primary
# all source are stored in SRCS-ySRCS-y := main.c
CFLAGS += -O0CFLAGS += 
include $(RTE_SDK)/mk/rte.extapp.mk

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Secondary进程：

#include #include #include #include #include #include #include #include #include #include 
#include #include 
#define RTE_LOGTYPE_APP RTE_LOGTYPE_USER1
static const char *_MSG_POOL = "MSG_POOL";static const char *_SEC_2_PRI = "SEC_2_PRI";static const char *_PRI_2_SEC = "PRI_2_SEC";
struct rte_ring *send_ring, *recv_ring;struct rte_mempool *message_pool;volatile int quit = 0;int string_size = 100;
static int lcore_send(__attribute__((unused)) void *arg){        unsigned lcore_id = rte_lcore_id();
        while(1)        {                void *msg = NULL;                if (rte_mempool_get(message_pool, &msg) < 0)                        continue;
                snprintf((char *)msg , string_size , "%s", "secondary to primary");                if (rte_ring_enqueue(send_ring , msg) < 0)                 {                        rte_mempool_put(message_pool, msg);                }                sleep(1);        }        return 0;}
pthread_t id1;
int main(int argc, char **argv){        const unsigned flags = 0;        const unsigned ring_size = 64;        const unsigned pool_size = 1024;        const unsigned pool_cache = 32;        const unsigned priv_data_sz = 0;
        int ret;        unsigned lcore_id;        ret = rte_eal_init(argc, argv);        if (ret < 0)                rte_exit(EXIT_FAILURE, "Cannot init EAL\n");
        recv_ring = rte_ring_lookup(_PRI_2_SEC);        send_ring = rte_ring_lookup(_SEC_2_PRI);        message_pool = rte_mempool_lookup(_MSG_POOL);
        if (send_ring == NULL)                rte_exit(EXIT_FAILURE, "Problem getting sending ring\n");        if (recv_ring == NULL)                rte_exit(EXIT_FAILURE, "Problem getting receiving ring\n");        if (message_pool == NULL)                rte_exit(EXIT_FAILURE, "Problem getting message pool\n");
        pthread_create(&id1 , NULL , lcore_send , NULL);    while (1)        {                lcore_id = rte_lcore_id();        void * msg = NULL;        if (rte_ring_dequeue(recv_ring, &msg) < 0)                {            usleep(5);            continue;        }
        printf("lcore_id = %d Received: %s\n" , lcore_id , (char *)msg);
        rte_mempool_put(message_pool, msg);    }
        return 0;}

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同样在Makefile文件里面要关闭WERROR相关编译选项：

#   BSD LICENSE##   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.#   All rights reserved.##   Redistribution and use in source and binary forms, with or without#   modification, are permitted provided that the following conditions#   are met:##     * Redistributions of source code must retain the above copyright#       notice, this list of conditions and the following disclaimer.#     * Redistributions in binary form must reproduce the above copyright#       notice, this list of conditions and the following disclaimer in#       the documentation and/or other materials provided with the#       distribution.#     * Neither the name of Intel Corporation nor the names of its#       contributors may be used to endorse or promote products derived#       from this software without specific prior written permission.##   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
ifeq ($(RTE_SDK),)$(error "Please define RTE_SDK environment variable")endif
# Default target, can be overridden by command line or environmentRTE_TARGET ?= arm64-armv8a-linuxapp-gcc
include $(RTE_SDK)/mk/rte.vars.mk
# binary nameAPP = rte_ring_secondary
# all source are stored in SRCS-ySRCS-y := main.c
CFLAGS += -O3CFLAGS += $()
include $(RTE_SDK)/mk/rte.extapp.mk

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运行，这里说一下，基于rte_ring的进程间通信，Secondary进程最好是使用auto类型：

./rte_ring_primary --proc-type primary./rte_ring_secondary --proc-type auto

运行效果：

作者简介

donatello1996，某大型企业资深嵌入式工程师，电子发烧友论坛技术大牛，同时也是飞凌嵌入式多年铁粉，曾基于飞凌多款板卡产出过优质测评文章或使用心得。本期三篇文章为donatello1996在使用OKMX8MP-C开发板过程中精心产出的干货，在此对donatello1996表示感谢。