RDMA编程实践-SEND-RECEICVE原语应用

RDMA编程实践

本文描述了RDMA编程过程中的SEND-RECEIVE双边原语的代码实现。包含多个版本，1、client向server发送消息，server回复client收到消息(ACK)，然后两边断开连接。2、server端循环等待客户端建立连接，client发送一次消息后，双方断开连接。3、server端循环等待客户端建立连接，一旦建立，client端可以一直向server端发送消息，直到发送消息为disconnect，server和client断开链接，但是server此时仍然可以等待别的client发送消息。
代码基于代码基于send-receive样例实现。关于代码注释，可以参考代码解释：
Makefile文件、会编译当前目录下的所有.c文件：

.PHONY: all cleanCC := gcc
CFLAGS := -Wall -g
LDLIBS := -lrdmacm -libverbs -lpthread -gSRCS := $(wildcard *.c)
APPS := $(SRCS:.c=)all: $(APPS)%: %.c$(CC) $(CFLAGS) $< -o $@ $(LDLIBS)clean:rm -f $(APPS)

version1 客户端-服务端消息一次传递

在这个阶段，我们希望能实现下面这样一个场景。client与server端相连接，client端能够发送一条消息给server，server收到该条消息之后恢复一条消息给client端表示我已经确认收到。之后两者断开连接。

代码：

// client1.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <getopt.h>
#include <rdma/rdma_cma.h>
#include <rdma/rdma_verbs.h>static const char *server = "10.10.10.1";
static const char *port = "7471";static struct rdma_cm_id *id;
static struct ibv_mr *mr, *send_mr;
static int send_flags;
static uint8_t send_msg[16];
static uint8_t recv_msg[16];static int run(void)
{struct rdma_addrinfo hints, *res;struct ibv_qp_init_attr attr;struct ibv_wc wc;int ret;memset(&hints, 0, sizeof hints);hints.ai_port_space = RDMA_PS_TCP;ret = rdma_getaddrinfo(server, port, &hints, &res);if (ret) {printf("rdma_getaddrinfo: %s\n", gai_strerror(ret));goto out;}memset(&attr, 0, sizeof attr);attr.cap.max_send_wr = attr.cap.max_recv_wr = 1;attr.cap.max_send_sge = attr.cap.max_recv_sge = 1;attr.cap.max_inline_data = 16;attr.qp_context = id;attr.sq_sig_all = 1;ret = rdma_create_ep(&id, res, NULL, &attr);// Check to see if we got inline data allowed or notif (attr.cap.max_inline_data >= 16)send_flags = IBV_SEND_INLINE;elseprintf("rdma_client: device doesn't support IBV_SEND_INLINE, ""using sge sends\n");if (ret) {perror("rdma_create_ep");goto out_free_addrinfo;}mr = rdma_reg_msgs(id, recv_msg, 16);if (!mr) {perror("rdma_reg_msgs for recv_msg");ret = -1;goto out_destroy_ep;}if ((send_flags & IBV_SEND_INLINE) == 0) {send_mr = rdma_reg_msgs(id, send_msg, 16);if (!send_mr) {perror("rdma_reg_msgs for send_msg");ret = -1;goto out_dereg_recv;}}ret = rdma_post_recv(id, NULL, recv_msg, 16, mr);if (ret) {perror("rdma_post_recv");goto out_dereg_send;}ret = rdma_connect(id, NULL);if (ret) {perror("rdma_connect");goto out_dereg_send;}printf("client send: %s\n", (char *)send_msg);ret = rdma_post_send(id, NULL, send_msg, 16, send_mr, send_flags);if (ret) {perror("rdma_post_send");goto out_disconnect;}while ((ret = rdma_get_send_comp(id, &wc)) == 0);if (ret < 0) {perror("rdma_get_send_comp");goto out_disconnect;}while ((ret = rdma_get_recv_comp(id, &wc)) == 0);if (ret < 0)perror("rdma_get_recv_comp");elseret = 0;printf("client received: %s\n", (char *) recv_msg);out_disconnect:rdma_disconnect(id);
out_dereg_send:if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);
out_dereg_recv:rdma_dereg_mr(mr);
out_destroy_ep:rdma_destroy_ep(id);
out_free_addrinfo:rdma_freeaddrinfo(res);
out:return ret;
}int main(int argc, char **argv)
{int ret;char *s = "hello world";// printf("client send: %s\n", s);memcpy(send_msg, s , strlen(s));printf("rdma_client: start\n");ret = run();printf("rdma_client: end %d\n", ret);return ret;
}

server端代码

// server1.c
/** Copyright (c) 2005-2009 Intel Corporation.  All rights reserved.** This software is available to you under the OpenIB.org BSD license* below:**     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.** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AWV* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE* SOFTWARE.*/#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <getopt.h>
#include <netdb.h>
#include <rdma/rdma_cma.h>
#include <rdma/rdma_verbs.h>static const char *server = "0.0.0.0";
static const char *port = "7471";static struct rdma_cm_id *listen_id, *id;
static struct ibv_mr *mr, *send_mr;
static int send_flags;
static uint8_t send_msg[16];
static uint8_t recv_msg[16];static int run(void)
{struct rdma_addrinfo hints, *res;struct ibv_qp_init_attr init_attr;struct ibv_qp_attr qp_attr;struct ibv_wc wc;int ret;memset(&hints, 0, sizeof hints);hints.ai_flags = RAI_PASSIVE;hints.ai_port_space = RDMA_PS_TCP;ret = rdma_getaddrinfo(server, port, &hints, &res);if (ret) {printf("rdma_getaddrinfo: %s\n", gai_strerror(ret));return ret;}memset(&init_attr, 0, sizeof init_attr);init_attr.cap.max_send_wr = init_attr.cap.max_recv_wr = 1;init_attr.cap.max_send_sge = init_attr.cap.max_recv_sge = 1;init_attr.cap.max_inline_data = 16;init_attr.sq_sig_all = 1;ret = rdma_create_ep(&listen_id, res, NULL, &init_attr);if (ret) {perror("rdma_create_ep");goto out_free_addrinfo;}ret = rdma_listen(listen_id, 0);if (ret) {perror("rdma_listen");goto out_destroy_listen_ep;}ret = rdma_get_request(listen_id, &id);if (ret) {perror("rdma_get_request");goto out_destroy_listen_ep;}memset(&qp_attr, 0, sizeof qp_attr);memset(&init_attr, 0, sizeof init_attr);ret = ibv_query_qp(id->qp, &qp_attr, IBV_QP_CAP,&init_attr);if (ret) {perror("ibv_query_qp");goto out_destroy_accept_ep;}if (init_attr.cap.max_inline_data >= 16)send_flags = IBV_SEND_INLINE;elseprintf("rdma_server: device doesn't support IBV_SEND_INLINE, ""using sge sends\n");mr = rdma_reg_msgs(id, recv_msg, 16);if (!mr) {ret = -1;perror("rdma_reg_msgs for recv_msg");goto out_destroy_accept_ep;}if ((send_flags & IBV_SEND_INLINE) == 0) {send_mr = rdma_reg_msgs(id, send_msg, 16);if (!send_mr) {ret = -1;perror("rdma_reg_msgs for send_msg");goto out_dereg_recv;}}ret = rdma_post_recv(id, NULL, recv_msg, 16, mr);if (ret) {perror("rdma_post_recv");goto out_dereg_send;}ret = rdma_accept(id, NULL);if (ret) {perror("rdma_accept");goto out_dereg_send;}while ((ret = rdma_get_recv_comp(id, &wc)) == 0);if (ret < 0) {perror("rdma_get_recv_comp");goto out_disconnect;}printf("server received: %s\n" , (char *)recv_msg);char *s = "ACK";memcpy(send_msg, s, strlen(s));printf("server send: %s\n", (char *)send_msg);ret = rdma_post_send(id, NULL, send_msg, 16, send_mr, send_flags);if (ret) {perror("rdma_post_send");goto out_disconnect;}while ((ret = rdma_get_send_comp(id, &wc)) == 0);if (ret < 0)perror("rdma_get_send_comp");elseret = 0;out_disconnect:rdma_disconnect(id);
out_dereg_send:if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);
out_dereg_recv:rdma_dereg_mr(mr);
out_destroy_accept_ep:rdma_destroy_ep(id);
out_destroy_listen_ep:rdma_destroy_ep(listen_id);
out_free_addrinfo:rdma_freeaddrinfo(res);return ret;
}int main(int argc, char **argv)
{int ret;printf("rdma_server: start\n");ret = run();printf("rdma_server: end %d\n", ret);return ret;
}

首先make编译完之后，在server端执行 ./server1，然后在客户端执行./client1
运行结果：
在这里插入图片描述

可以看到 client向server发送了hello world，server收到之后打印出来并回复给client端ACK消息，client收到之后并打印。最后双方断开连接，完成！

version2-客户端发送一次，服务端循环等待

client2的代码跟上面一样，server2代码不一样。
server2的逻辑：在run函数进来之后记录一个connect点，当远程客户端发送完信息后，释放连接的资源，跳转到connect阶段准备让下一个client连接。

/** Copyright (c) 2005-2009 Intel Corporation.  All rights reserved.** This software is available to you under the OpenIB.org BSD license* below:**     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.** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AWV* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE* SOFTWARE.*/#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <getopt.h>
#include <netdb.h>
#include <rdma/rdma_cma.h>
#include <rdma/rdma_verbs.h>#define N 100
#define MAX_CAP 32static const char *server = "0.0.0.0";
static const char *port = "7471";static struct rdma_cm_id *listen_id, *id;
static struct ibv_mr *mr, *send_mr;
static int send_flags;
static uint8_t send_msg[MAX_CAP];
static uint8_t recv_msg[MAX_CAP];static int run(void)
{struct rdma_addrinfo hints, *res;struct ibv_qp_init_attr init_attr;struct ibv_qp_attr qp_attr;struct ibv_wc wc;int ret;while(1){memset(&hints, 0, sizeof hints);hints.ai_flags = RAI_PASSIVE;hints.ai_port_space = RDMA_PS_TCP;ret = rdma_getaddrinfo(server, port, &hints, &res);if (ret) {printf("rdma_getaddrinfo: %s\n", gai_strerror(ret));return ret;}memset(&init_attr, 0, sizeof init_attr);init_attr.cap.max_send_wr = init_attr.cap.max_recv_wr = N;init_attr.cap.max_send_sge = init_attr.cap.max_recv_sge = 1;init_attr.cap.max_inline_data = MAX_CAP;init_attr.sq_sig_all = 1;ret = rdma_create_ep(&listen_id, res, NULL, &init_attr);if (ret) {perror("rdma_create_ep");goto out_free_addrinfo;}ret = rdma_listen(listen_id, 0);if (ret) {perror("rdma_listen");goto out_destroy_listen_ep;}ret = rdma_get_request(listen_id, &id);if (ret) {perror("rdma_get_request");goto out_destroy_listen_ep;}memset(&qp_attr, 0, sizeof qp_attr);memset(&init_attr, 0, sizeof init_attr);ret = ibv_query_qp(id->qp, &qp_attr, IBV_QP_CAP,&init_attr);if (ret) {perror("ibv_query_qp");goto out_destroy_accept_ep;}if (init_attr.cap.max_inline_data >= MAX_CAP)send_flags = IBV_SEND_INLINE;elseprintf("rdma_server: device doesn't support IBV_SEND_INLINE, ""using sge sends\n");mr = rdma_reg_msgs(id, recv_msg, N);if (!mr) {ret = -1;perror("rdma_reg_msgs for recv_msg");goto out_destroy_accept_ep;}if ((send_flags & IBV_SEND_INLINE) == 0) {send_mr = rdma_reg_msgs(id, send_msg, MAX_CAP);if (!send_mr) {ret = -1;perror("rdma_reg_msgs for send_msg");goto out_dereg_recv;}}   ret = rdma_accept(id, NULL);if (ret) {perror("rdma_accept");goto out_dereg_send;}memset(recv_msg, 0 , sizeof recv_msg);memset(send_msg, 0 , sizeof send_msg);ret = rdma_post_recv(id, NULL, recv_msg, MAX_CAP, mr);if (ret) {perror("rdma_post_recv");goto out_dereg_send;}while ((ret = rdma_get_recv_comp(id, &wc)) == 0);if (ret < 0) {perror("rdma_get_recv_comp");goto out_disconnect;}printf("server received: %s\n", (char *)recv_msg);memcpy(send_msg, recv_msg, sizeof(recv_msg));ret = rdma_post_send(id, NULL, send_msg, MAX_CAP, send_mr, send_flags);if (ret) {perror("rdma_post_send");goto out_disconnect;}while ((ret = rdma_get_send_comp(id, &wc)) == 0); // 确认对方已经收到 对方会发送ackif (ret < 0)perror("rdma_get_send_comp");elseret = 0;rdma_disconnect(id);if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);rdma_dereg_mr(mr);rdma_destroy_ep(id);rdma_destroy_ep(listen_id);rdma_freeaddrinfo(res);  }out_disconnect:rdma_disconnect(id);
out_dereg_send:if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);
out_dereg_recv:rdma_dereg_mr(mr);
out_destroy_accept_ep:rdma_destroy_ep(id);
out_destroy_listen_ep:rdma_destroy_ep(listen_id);
out_free_addrinfo:rdma_freeaddrinfo(res);  return ret;
}int main(int argc, char **argv)
{int ret;printf("rdma_server: start\n");ret = run();printf("rdma_server: end %d\n", ret);return ret;
}

运行结果：
在这里插入图片描述

在这里插入图片描述

可以看到客户端发送一次消息之后便结束了，服务端却一直等待连接，直到按下ctrl+c。

version3-客户端循环发送，服务端循环等待，一次连接

和上述版本2不同的时候，这里client和server只连接一次，然后可以多次发送消息。直到client发送的消息为disconnect

// client3.c
/** Copyright (c) 2010 Intel Corporation.  All rights reserved.** This software is available to you under the OpenIB.org BSD license* below:**     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.** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AWV* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE* SOFTWARE.*/#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <getopt.h>
#include <rdma/rdma_cma.h>
#include <rdma/rdma_verbs.h>#define N 100
#define MAX_CAP 32static const char *server = "10.10.10.1";
static const char *port = "7471";static struct rdma_cm_id *id;
static struct ibv_mr *mr, *send_mr;
static int send_flags;
static uint8_t send_msg[MAX_CAP];
static uint8_t recv_msg[MAX_CAP];static int run(void)
{struct rdma_addrinfo hints, *res;struct ibv_qp_init_attr attr;struct ibv_wc wc;int ret;memset(&hints, 0, sizeof hints);hints.ai_port_space = RDMA_PS_TCP;ret = rdma_getaddrinfo(server, port, &hints, &res);if (ret) {printf("rdma_getaddrinfo: %s\n", gai_strerror(ret));goto out;}memset(&attr, 0, sizeof attr);attr.cap.max_send_wr = attr.cap.max_recv_wr = 5;attr.cap.max_send_sge = attr.cap.max_recv_sge = 1;attr.cap.max_inline_data = MAX_CAP;attr.qp_context = id;attr.sq_sig_all = 1;ret = rdma_create_ep(&id, res, NULL, &attr);// Check to see if we got inline data allowed or notif (attr.cap.max_inline_data >= MAX_CAP)send_flags = IBV_SEND_INLINE;elseprintf("rdma_client: device doesn't support IBV_SEND_INLINE, ""using sge sends\n");if (ret) {perror("rdma_create_ep");goto out_free_addrinfo;}mr = rdma_reg_msgs(id, recv_msg, MAX_CAP);if (!mr) {perror("rdma_reg_msgs for recv_msg");ret = -1;goto out_destroy_ep;}if ((send_flags & IBV_SEND_INLINE) == 0) {send_mr = rdma_reg_msgs(id, send_msg, MAX_CAP);if (!send_mr) {perror("rdma_reg_msgs for send_msg");ret = -1;goto out_dereg_recv;}}// ret = rdma_post_recv(id, NULL, recv_msg, 16, mr);// if (ret) {//     perror("rdma_post_recv");//     goto out_dereg_send;// }// printf("123\n");ret = rdma_connect(id, NULL);if (ret) {perror("rdma_connect");goto out_dereg_send;}while(1){// sleep(5);memset(recv_msg, 0 , sizeof recv_msg);memset(send_msg, 0 , sizeof send_msg);printf("input send message: ");scanf("%s", send_msg);getchar();ret = rdma_post_recv(id, NULL, recv_msg, MAX_CAP, mr);if (ret) {perror("rdma_post_recv");goto out_dereg_send;}ret = rdma_post_send(id, NULL, send_msg, MAX_CAP, send_mr, send_flags);if (ret) {perror("rdma_post_send");goto out_disconnect;}while ((ret = rdma_get_send_comp(id, &wc)) == 0);if (ret < 0) {perror("rdma_get_send_comp");goto out_disconnect;}while ((ret = rdma_get_recv_comp(id, &wc)) == 0);if (ret < 0)perror("rdma_get_recv_comp");elseret = 0;if(strcmp((char*)send_msg,"disconnect") == 0){printf("disconnect\n");goto out_disconnect;}else{printf("%s\n", recv_msg);}}out_disconnect:rdma_disconnect(id);
out_dereg_send:if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);
out_dereg_recv:rdma_dereg_mr(mr);
out_destroy_ep:rdma_destroy_ep(id);
out_free_addrinfo:rdma_freeaddrinfo(res);
out:return ret;}int main(int argc, char **argv)
{int ret;//memcpy(send_msg, argv[1], 50);// while ((op = getopt(argc, argv, "s:p:")) != -1) {// 	switch (op) {// 	case 's':// 		server = optarg;// 		break;// 	case 'p':// 		port = optarg;// 		break;// 	default:// 		printf("usage: %s\n", argv[0]);// 		printf("\t[-s server_address]\n");// 		printf("\t[-p port_number]\n");// 		exit(1);// 	}// }printf("rdma_client: start\n");ret = run();printf("rdma_client: end %d\n", ret);return ret;
}

// server3.c
/** Copyright (c) 2005-2009 Intel Corporation.  All rights reserved.** This software is available to you under the OpenIB.org BSD license* below:**     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.** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AWV* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE* SOFTWARE.*/#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <getopt.h>
#include <netdb.h>
#include <rdma/rdma_cma.h>
#include <rdma/rdma_verbs.h>#define N 100
#define MAX_CAP 32static const char *server = "0.0.0.0";
static const char *port = "7471";static struct rdma_cm_id *listen_id, *id;
static struct ibv_mr *mr, *send_mr;
static int send_flags;
static uint8_t send_msg[MAX_CAP];
static uint8_t recv_msg[MAX_CAP];static int run(void)
{struct rdma_addrinfo hints, *res;struct ibv_qp_init_attr init_attr;struct ibv_qp_attr qp_attr;struct ibv_wc wc;int ret;connect:memset(&hints, 0, sizeof hints);hints.ai_flags = RAI_PASSIVE;hints.ai_port_space = RDMA_PS_TCP;ret = rdma_getaddrinfo(server, port, &hints, &res);if (ret) {printf("rdma_getaddrinfo: %s\n", gai_strerror(ret));return ret;}memset(&init_attr, 0, sizeof init_attr);init_attr.cap.max_send_wr = init_attr.cap.max_recv_wr = N;init_attr.cap.max_send_sge = init_attr.cap.max_recv_sge = 1;init_attr.cap.max_inline_data = MAX_CAP;init_attr.sq_sig_all = 1;ret = rdma_create_ep(&listen_id, res, NULL, &init_attr);if (ret) {perror("rdma_create_ep");goto out_free_addrinfo;}ret = rdma_listen(listen_id, 0);if (ret) {perror("rdma_listen");goto out_destroy_listen_ep;}ret = rdma_get_request(listen_id, &id);if (ret) {perror("rdma_get_request");goto out_destroy_listen_ep;}memset(&qp_attr, 0, sizeof qp_attr);memset(&init_attr, 0, sizeof init_attr);ret = ibv_query_qp(id->qp, &qp_attr, IBV_QP_CAP,&init_attr);if (ret) {perror("ibv_query_qp");goto out_destroy_accept_ep;}if (init_attr.cap.max_inline_data >= MAX_CAP)send_flags = IBV_SEND_INLINE;elseprintf("rdma_server: device doesn't support IBV_SEND_INLINE, ""using sge sends\n");mr = rdma_reg_msgs(id, recv_msg, N);if (!mr) {ret = -1;perror("rdma_reg_msgs for recv_msg");goto out_destroy_accept_ep;}if ((send_flags & IBV_SEND_INLINE) == 0) {send_mr = rdma_reg_msgs(id, send_msg, MAX_CAP);if (!send_mr) {ret = -1;perror("rdma_reg_msgs for send_msg");goto out_dereg_recv;}}   ret = rdma_accept(id, NULL);if (ret) {perror("rdma_accept");goto out_dereg_send;}while (1) {memset(recv_msg, 0 , sizeof recv_msg);memset(send_msg, 0 , sizeof send_msg);ret = rdma_post_recv(id, NULL, recv_msg, MAX_CAP, mr);if (ret) {perror("rdma_post_recv");goto out_dereg_send;}while ((ret = rdma_get_recv_comp(id, &wc)) == 0);if (ret < 0) {perror("rdma_get_recv_comp");goto out_disconnect;}char *s = (char *)recv_msg;int total_length = strlen("server get ") + strlen(s); // 加1是为了存储字符串结束符'\0'char *recv_str = (char *)malloc(total_length);  // 分配足够的空间strcpy(recv_str, "server get ");strcat(recv_str, s);//printf("%s\n", recv_str);memcpy(send_msg, recv_str, strlen(recv_str));ret = rdma_post_send(id, NULL, send_msg, MAX_CAP, send_mr, send_flags);if (ret) {perror("rdma_post_send");goto out_disconnect;}if(strcmp((char*)recv_msg,"disconnect") == 0){//printf("%s\n",recv_msg);printf("client disconnect\n");rdma_disconnect(id);if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);rdma_dereg_mr(mr);rdma_destroy_ep(id);rdma_destroy_ep(listen_id);rdma_freeaddrinfo(res);  //goto out_disconnect;goto connect;}else{printf("%s\n", recv_msg);}// while ((ret = rdma_get_send_comp(id, &wc)) == 0); // 确认对方已经收到 对方发送ack// printf("after send\n");// if (ret < 0)//     perror("rdma_get_send_comp");// else//     ret = 0;}out_disconnect:rdma_disconnect(id);
out_dereg_send:if ((send_flags & IBV_SEND_INLINE) == 0)rdma_dereg_mr(send_mr);
out_dereg_recv:rdma_dereg_mr(mr);
out_destroy_accept_ep:rdma_destroy_ep(id);
out_destroy_listen_ep:rdma_destroy_ep(listen_id);
out_free_addrinfo:rdma_freeaddrinfo(res);  return ret;
}int main(int argc, char **argv)
{int op, ret;while ((op = getopt(argc, argv, "s:p:")) != -1) {switch (op) {case 's':server = optarg;break;case 'p':port = optarg;break;default:printf("usage: %s\n", argv[0]);printf("\t[-s server_address]\n");printf("\t[-p port_number]\n");exit(1);}}printf("rdma_server: start\n");ret = run();printf("rdma_server: end %d\n", ret);return ret;
}

运行结果：

在这里插入图片描述

总结：

本文实现了rdma中send-receive双边原语的三种需求版本，从单次发送到两者都能多次发送。理解其中的代码逻辑，想要发送消息之前对端得创建一个recv队列用来接收消息。发送完了有一个发送完成队列，接收完了也有一个接收完成队列。最后双方断开连接需要一起断开，不能某一方执行disconnect另一方不执行。本次实验有一个关键点：

while ((ret = rdma_get_send_comp(id, &wc)) == 0)

这一行代码是等待发送成功，发送成功之后，对方会给一个隐式信息表示我已经收到。这里耗费得时间比较长一点，在版本3中，如果不注释掉，在server端的receive队列还没有建立好，这就导致client发送了消息，server还没有收到，双方就陷入了死循环中。