thread.c

   1 #define _REENTRANT
   2 #include <pthread.h>
   3 #include <stdio.h>
   4 #include <fcntl.h>
   5 #include <stdlib.h>
   6
   7 #define MAX_THREADS 1024
   8 #define RSIZE (16*1024)
   9 static int num_threads;
  10 static size_t read_size;
  11 static pthread_t tid[MAX_THREADS];
  12 static pid_t pid[MAX_THREADS];
  13
  14 static void thread_main(void)
  15 {
  16         char buf[RSIZE];
  17         int fd1, fd2;
  18         int i;
  19
  20         sleep(1);
  21
  22         fd1 = open("/dev/zero", O_RDONLY);
  23         fd2 = open("/dev/null", O_WRONLY);
  24
  25         for (i=0;i<read_size;i++) {
  26                 if (read(fd1, buf, RSIZE) != RSIZE) {
  27                         printf("read failed\n");
  28                         exit(1);
  29                 }
  30                 if (write(fd2, buf, RSIZE) != RSIZE) {
  31                         printf("write failed\n");
  32                         exit(1);
  33                 }
  34         }
  35         close(fd1);
  36         close(fd2);
  37 }
  38
  39
  40 static void fork_test(void)
  41 {
  42         int i;
  43         time_t start = time(NULL);
  44
  45         for (i=0;i < num_threads; i++) {
  46                 if ((pid[i] = fork()) == 0) {
  47                         thread_main();
  48                         _exit(0);
  49                 }
  50                 if (pid[i] == (pid_t)-1) {
  51                         printf("fork %d failed\n", i);
  52                         exit(1);
  53                 }
  54         }
  55
  56         for (i=0;i < num_threads; i++) {
  57                 waitpid(pid[i], NULL, 0);
  58         }
  59
  60         printf("using fork took %d seconds\n", time(NULL) - start);
  61 }
  62
  63
  64 static void pthread_test(void)
  65 {
  66         int i;
  67         time_t start = time(NULL);
  68
  69         for (i=0;i < num_threads; i++) {
  70                 if (pthread_create(&tid[i], NULL, thread_main, NULL) != 0) {
  71                         printf("pthread_create failed\n");
  72                         exit(1);
  73                 }
  74         }
  75
  76         for (i=0;i < num_threads; i++) {
  77                 pthread_join(tid[i], NULL);
  78         }
  79
  80         printf("using pthreads took %d seconds\n", time(NULL) - start);
  81 }
  82
  83
  84 int main(int argc, char *argv[])
  85 {
  86         if (argc < 2) {
  87                 printf("usage: %s <num_threads> <num_loops>\n",argv[0]);
  88                 exit(1);
  89         }
  90
  91         num_threads = atoi(argv[1]);
  92         read_size = atoi(argv[2]);
  93
  94         if (num_threads > MAX_THREADS) {
  95                 printf("max_threads is %d\n", MAX_THREADS);
  96                 exit(1);
  97         }
  98
  99         fork_test();
 100         pthread_test();
 101         fork_test();
 102         pthread_test();
 103
 104         printf("all done\n");
 105 }
 106