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二、io_uring 版本：异步 send/recv 压测

io_uring 核心：把send/recv提交到SQ，内核异步执行，批量收割CQE。减少系统调用次数，高性能网络首选。

网络io_uring有两种模式：

1. IORING_OP_SEND/IORING_OP_RECV：原生异步send/recv（最简单，下面示例）
2. io_uring 多连接模式 + accept（IORING_OP_ACCEPT）

⚠️ 编译需要链接 liburing：apt install liburing-dev/yum install liburing-devel

io_uring_server.c

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <netinet/in.h> #include <liburing.h> #include <time.h> #define PORT 8888 #define BUF_SIZE (1<<20) #define QUEUE_DEPTH 16 static int set_nonblock(int fd) { int flags = fcntl(fd, F_GETFL, 0); return fcntl(fd, F_SETFL, flags | O_NONBLOCK); } int main() { int listen_fd = socket(AF_INET, SOCK_STREAM, 0); set_nonblock(listen_fd); struct sockaddr_in addr = {0}; addr.sin_family = AF_INET; addr.sin_addr.s_addr = INADDR_ANY; addr.sin_port = htons(PORT); bind(listen_fd, (struct sockaddr*)&addr, sizeof(addr)); listen(listen_fd, 128); struct io_uring ring; io_uring_queue_init(QUEUE_DEPTH, &ring, 0); char *buf = malloc(BUF_SIZE); struct io_uring_sqe *sqe; struct io_uring_cqe *cqe; int conn_fd = -1; long long total_recv = 0; clock_t start = 0; // submit accept sqe = io_uring_get_sqe(&ring); io_uring_prep_accept(sqe, listen_fd, NULL, NULL, 0); io_uring_submit(&ring); while (1) { io_uring_wait_cqe(&ring, &cqe); if (cqe->res < 0) { perror("cqe err"); io_uring_cqe_seen(&ring, cqe); continue; } if (conn_fd < 0) { // accept完成 conn_fd = cqe->res; printf("io_uring client connected fd=%d\n", conn_fd); start = clock(); io_uring_cqe_seen(&ring, cqe); // 提交recv sqe = io_uring_get_sqe(&ring); io_uring_prep_recv(sqe, conn_fd, buf, BUF_SIZE, 0); io_uring_submit(&ring); } else { // recv完成 int n = cqe->res; io_uring_cqe_seen(&ring, cqe); if (n <= 0) { clock_t end = clock(); double sec = (double)(end - start)/CLOCKS_PER_SEC; printf("io_uring server recv total: %lld bytes, bw: %.2f MB/s\n", total_recv, total_recv / sec / (1<<20)); close(conn_fd); free(buf); io_uring_queue_exit(&ring); close(listen_fd); return 0; } total_recv += n; // 继续提交下一次recv sqe = io_uring_get_sqe(&ring); io_uring_prep_recv(sqe, conn_fd, buf, BUF_SIZE, 0); io_uring_submit(&ring); } } }

io_uring_client.c

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <liburing.h> #include <time.h> #define PORT 8888 #define BUF_SIZE (1<<20) #define SEND_TOTAL (10LL << 30) #define QUEUE_DEPTH 16 int main() { int sock = socket(AF_INET, SOCK_STREAM, 0); struct sockaddr_in serv_addr = {0}; serv_addr.sin_family = AF_INET; serv_addr.sin_port = htons(PORT); inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr); connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); struct io_uring ring; io_uring_queue_init(QUEUE_DEPTH, &ring, 0); char *buf = malloc(BUF_SIZE); memset(buf, 'A', BUF_SIZE); long long remain = SEND_TOTAL; clock_t start = clock(); struct io_uring_sqe *sqe; struct io_uring_cqe *cqe; // 提交第一次send sqe = io_uring_get_sqe(&ring); int send_len = remain > BUF_SIZE ? BUF_SIZE : remain; io_uring_prep_send(sqe, sock, buf, send_len, MSG_NOSIGNAL); io_uring_submit(&ring); while (remain > 0) { io_uring_wait_cqe(&ring, &cqe); if (cqe->res < 0) { perror("send cqe err"); exit(1); } int n = cqe->res; io_uring_cqe_seen(&ring, cqe); remain -= n; if (remain <= 0) break; // 继续提交send sqe = io_uring_get_sqe(&ring); send_len = remain > BUF_SIZE ? BUF_SIZE : remain; io_uring_prep_send(sqe, sock, buf, send_len, MSG_NOSIGNAL); io_uring_submit(&ring); } clock_t end = clock(); double sec = (double)(end - start)/CLOCKS_PER_SEC; printf("io_uring client send total: %lld bytes, bw: %.2f MB/s\n", SEND_TOTAL, SEND_TOTAL / sec / (1<<20)); close(sock); free(buf); io_uring_queue_exit(&ring); return 0; }

编译&运行：

gcc io_uring_server.c -o io_uring_server -O2 -luring gcc io_uring_client.c -o io_uring_client -O2 -luring # 窗口1 ./io_uring_server # 窗口2 ./io_uring_client

io_uring关键点：

1. QUEUE_DEPTH：SQ/CQ队列深度，对性能影响很大，小包场景调大可以批量提交；
2. io_uring_submit()：可以攒一批SQE一次性提交，减少syscall；
3. 高级：使用IORING_OP_SEND_ZC零拷贝send（内核5.18+），进一步减少内存拷贝。

三、压测指标采集 & perf 分析（必做）

# 看CPU，sys占比是重点 perf stat ./io_uring_server # 火焰图看调用栈 perf record -g ./io_uring_server perf script | ./FlameGraph/stackcollapse-perf.pl | ./FlameGraph/flamegraph.pl > io_uring.svg

采集指标：

1. 吞吐 MB/s（server recv字节为准）
2. 系统CPU%：epoll小包会sys很高；io_uring因为批量提交sys开销更低
3. 平均延迟：改成ping-pong小包测试
4. 内存占用、socket buffer溢出（ss -ti看tcp队列）

内核调优（网络压测）

sysctl -w net.core.rmem_max=33554432 sysctl -w net.core.wmem_max=33554432 sysctl -w net.ipv4.tcp_rmem="4096 87380 33554432" sysctl -w net.ipv4.tcp_wmem="4096 65536 33554432"

四、epoll vs io_uring 对比总结

参考链接 ：0voice · GitHub