test

吕锦中202441429012406/task66.c

@@ -0,0 +1,59 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#define ITERATIONS 10000
+
+double get_time() {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return tv.tv_sec + tv.tv_usec / 1000000.0;
+}
+
+void *dummy_thread(void *arg) {
+    return NULL;
+}
+
+int main() {
+    double t_start, t_end;
+    double fork_total = 0, pthread_total = 0;
+
+    /* Measure fork() */
+    t_start = get_time();
+    for (int i = 0; i < ITERATIONS; i++) {
+        pid_t pid = fork();
+        if (pid == 0) {
+            _exit(0);
+        } else if (pid > 0) {
+            waitpid(pid, NULL, 0);
+        }
+    }
+    t_end = get_time();
+    fork_total = t_end - t_start;
+
+    /* Measure pthread_create() */
+    t_start = get_time();
+    for (int i = 0; i < ITERATIONS; i++) {
+        pthread_t tid;
+        pthread_create(&tid, NULL, dummy_thread, NULL);
+        pthread_join(tid, NULL);
+    }
+    t_end = get_time();
+    pthread_total = t_end - t_start;
+
+    printf("=== Performance Comparison ===\n");
+    printf("Iterations: %d\n", ITERATIONS);
+    printf("fork() total time:           %.6f s (avg: %.3f us)\n",
+           fork_total, fork_total / ITERATIONS * 1000000);
+    printf("pthread_create() total time: %.6f s (avg: %.3f us)\n",
+           pthread_total, pthread_total / ITERATIONS * 1000000);
+    printf("Ratio (fork/pthread): %.2fx\n", fork_total / pthread_total);
+    printf("\nExplanation: fork() creates a new process with a copy of the\n");
+    printf("entire address space, which is much heavier than pthread_create()\n");
+    printf("which only creates a new thread sharing the same address space.\n");
+
+    return 0;
+}