epoll_create failed: Function not implemented
最近在使用epoll时，出现了一个问题。
将程序移植到mips板子上时运行epoll监控程序时，出现如下打印信息：
socket done bind done listen done epoll_create failed: Function not implemented
同样的源代码在pc上（x86）编译完后就运行正常，打印信息如下：
socket done bind done listen done no socket ready for read within 5 secs no socket ready for read within 5 secs no socket ready for read within 5 secs no socket ready for read within 5 secs no socket ready for read within 5 secs no socket ready for read within 5 secs no socket ready for read within 5 secs no socket ready for read within 5 secs ...
程序关于epoll部分的代码如下,请问是什么原因，如何解决这个问题，可以让epoll运行在板子上，谢谢。运动会口号
C/C++ code?#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <unistd.h> #include <fcntl.h> #include <arpa/inet.h> #include <sys/epoll.h> #include <errno.h> #define DEFAULT_PORT 1984 //默认端口 #define BUFF_SIZE 1024 //buffer大小 #define EPOLL_MAXEVENTS 64 //epoll_wait的最多返回的events个数 #define EPOLL_TIMEOUT 5000 //epoll_wait的timeout milliseconds //函数：设置sock为non-blocking mode void setSockNonBlock(int sock) { int flags; flags = fcntl(sock, F_GETFL, 0); if (flags < 0) { perror("fcntl(F_GETFL) failed"); exit(EXIT_FAILURE); } if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) { perror("fcntl(F_SETFL) failed"); exit(EXIT_FAILURE); } } int main(int argc, char *argv[]) { //获取自定义端口 unsigned short int port; if (argc == 2) { port = atoi(argv[1]); } else if (argc < 2) { port = DEFAULT_PORT; } else { fprintf(stderr, "USAGE: %s [port]\n", argv[0]); exit(EXIT_FAILURE); } //创建socket int sock; if ( (sock = socket(PF_INET, SOCK_STREAM, 0)) == -1 ) { perror("socket failed"); exit(EXIT_FAILURE); } printf("socket done\n"); //in case of 'address already in use' error message int yes = 1; if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int))) { perror("setsockopt failed"); exit(EXIT_FAILURE); } //设置sock为non-blocking setSockNonBlock(sock); //创建要bind的socket address struct sockaddr_in bind_addr; memset(&bind_addr, 0, sizeof(bind_addr)); bind_addr.sin_family = AF_INET; bind_addr.sin_addr.s_addr = htonl(INADDR_ANY); //设置接受任意地址 bind_addr.sin_port = htons(port); //将host byte order转换为network byte order //bind sock到创建的socket address上 if ( bind(sock, (struct sockaddr *) &bind_addr, sizeof(bind_addr)) == -1 ) { perror("bind failed"); exit(EXIT_FAILURE); } printf("bind done\n"); //listen if ( listen(sock, 5) == -1) { perror("listen failed"); exit(EXIT_FAILURE); } printf("listen done\n"); //创建epoll (epoll file descriptor) int epfd; if ( (epfd = epoll_create(5)) == -1 ) { perror("epoll_create failed"); exit(EXIT_FAILURE); } //将sock添加到epoll中 struct epoll_event event; event.events = EPOLLIN; event.data.fd = sock; if ( epoll_ctl(epfd, EPOLL_CTL_ADD, sock, &event) == -1 ) { perror("epoll_ctl"); exit(EXIT_FAILURE); } //初始化epoll_wait的参数 struct epoll_event events[EPOLL_MAXEVENTS]; memset(events, 0, sizeof(events)); //循环侦听 int conn_sock; struct sockaddr_in client_addr; socklen_t client_addr_len; char client_ip_str[INET_ADDRSTRLEN]; int res; int i; char buffer[BUFF_SIZE]; int recv_size; while (1) { //每次循环调用依次epoll_wait侦听 res = epoll_wait(epfd, events, EPOLL_MAXEVENTS, EPOLL_TIMEOUT); if (res < 0) { perror("epoll_wait failed"); exit(EXIT_FAILURE); } else if (res == 0) { fprintf(stderr, "no socket ready for read within %d secs\n", EPOLL_TIMEOUT / 1000); continue; } //检测到res个IO file descriptor的events，loop各个fd进行响应 for (i = 0; i < res; i++) { //events[i]即为检测到的event，域events[i].events表示具体哪些events，域events[i].data.fd即对应的IO fd if ( (events[i].events & EPOLLERR) || (events[i].events & EPOLLHUP) || (!(events[i].events & EPOLLIN)) ) { //由于events[i].events使用每个bit表示event，因此判断是否包含某个具体事件可以使用`&`操作符 //这里判断是否存在EPOLLERR, EPOLLHUP等event fprintf (stderr, "epoll error\n"); close (events[i].data.fd); continue; } //对检测到event的各IO fd进行响应 if (events[i].data.fd == sock) { //当前fd是server的socket，不进行读而是accept所有client连接请求 while (1) { client_addr_len = sizeof(client_addr); conn_sock = accept(sock, (struct sockaddr *) &client_addr, &client_addr_len); if (conn_sock == -1) { if ( (errno == EAGAIN) || (errno == EWOULDBLOCK) ) { //non-blocking模式下无新connection请求，跳出while (1) break; } else { perror("accept failed"); exit(EXIT_FAILURE); } } if (!inet_ntop(AF_INET, &(client_addr.sin_addr), client_ip_str, sizeof(client_ip_str))) { perror("inet_ntop failed"); exit(EXIT_FAILURE); } printf("accept a client from: %s\n", client_ip_str); //设置conn_sock为non-blocking setSockNonBlock(conn_sock); //把conn_sock添加到epoll的侦听中 event.events = EPOLLIN; event.data.fd = conn_sock; if ( epoll_ctl(epfd, EPOLL_CTL_ADD, conn_sock, &event) == -1 ) { perror("epoll_ctl(EPOLL_CTL_ADD) failed"); exit(EXIT_FAILURE); } } } else { //当前fd是client连接的socket，可以读(read from client) conn_sock = events[i].data.fd; memset(buffer, 0, sizeof(buffer)); if ( (recv_size = recv(conn_sock, buffer, sizeof(buffer), 0)) == -1 && (errno != EAGAIN) ) { //recv在non-blocking模式下，返回-1且errno为EAGAIN表示当前无可读数据，并不表示错误 perror("recv failed"); exit(EXIT_FAILURE); } printf("recved from conn_sock=%d : %s(%d length string)\n", conn_sock, buffer, recv_size); //立即将收到的内容写回去 if ( send(conn_sock, buffer, recv_size, 0) == -1 && (errno != EAGAIN) && (errno != EWOULDBLOCK) ) { //send在non-blocking模式下，返回-1且errno为EAGAIN或EWOULDBLOCK表示当前无可写数据，并不表示错误 perror("send failed"); exit(EXIT_FAILURE); } printf("send to conn_sock=%d done\n", conn_sock); //将当前socket从epoll的侦听中移除(有文章说：关闭con_sock之后，其会自动从epoll中删除，因此此段代码可以省略) if ( epoll_ctl(epfd, EPOLL_CTL_DEL, conn_sock, NULL) == -1 ) { perror("epoll_ctl(EPOLL_CTL_DEL) failed"); exit(EXIT_FAILURE); } //关闭连接 if ( close(conn_sock) == -1 ) { perror("close failed"); exit(EXIT_FAILURE); } printf("close conn_sock=%d done\n", conn_sock); } } } close(sock); //关闭server的listening socket close(epfd); //关闭epoll file descriptor return 0; }
epoll_create() was added to the kernel in version 2.6. Library support is provided in glibc starting with version 2.3.2.
可能是内核没有支持,重新配置内核,编译好后使用新的kernel.
方法共享：
法一：修改kernel源文件中的 .config的CONFIG_EPOLL=y
法二：通过在kernel源文件中make menuconfig 中将eventpoll项勾上就可以了。