81 lines
1.8 KiB
C
81 lines
1.8 KiB
C
/*
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任务6（任选）：测量和比较fork、pthread_create函数调用所需的执行时间，并进行解释。
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可以多次反复调用读写函数，计算累积时间。
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <pthread.h>
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#include <sys/time.h>
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#include <sys/wait.h>
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#define ITERATIONS 1000
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double get_time()
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{
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struct timeval tv;
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gettimeofday(&tv, NULL);
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return tv.tv_sec + tv.tv_usec / 1000000.0;
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}
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void *dummy_thread(void *arg)
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{
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return NULL;
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}
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double measure_fork_create()
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{
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double t_start = get_time();
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for (int i = 0; i < ITERATIONS; i++)
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{
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pid_t pid = fork();
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if (pid < 0)
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{
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perror("fork");
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exit(1);
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}
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if (pid == 0)
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{
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/* 子进程立即退出 */
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_exit(0);
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}
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else
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{
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/* 父进程等待子进程结束 */
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waitpid(pid, NULL, 0);
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}
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}
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double t_end = get_time();
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return (t_end - t_start) / ITERATIONS;
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}
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double measure_pthread_create()
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{
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pthread_t tid;
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double t_start = get_time();
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for (int i = 0; i < ITERATIONS; i++)
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{
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pthread_create(&tid, NULL, dummy_thread, NULL);
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pthread_join(tid, NULL);
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}
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double t_end = get_time();
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return (t_end - t_start) / ITERATIONS;
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}
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int main()
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{
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printf("Measuring fork() and pthread_create() overhead...\n");
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printf("Iterations per test: %d\n\n", ITERATIONS);
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double avg_pthread_time = measure_pthread_create();
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printf("Average pthread_create() + pthread_join() time: %.6f ms\n",
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avg_pthread_time * 1000);
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double avg_fork_time = measure_fork_create();
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printf("Average fork() + waitpid() time: %.6f ms\n",
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avg_fork_time * 1000);
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return 0;
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}
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