nptl/cond-perf.c

   1 #include <pthread.h>
   2 #include <stdbool.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7
   8 static pthread_cond_t cond1 = PTHREAD_COND_INITIALIZER;
   9 static pthread_mutex_t mut1 = PTHREAD_MUTEX_INITIALIZER;
  10
  11 static pthread_cond_t cond2 = PTHREAD_COND_INITIALIZER;
  12 static pthread_mutex_t mut2 = PTHREAD_MUTEX_INITIALIZER;
  13
  14 static bool last_round;
  15 static int ntogo;
  16 static bool alldone;
  17
  18
  19 static void *
  20 cons (void *arg)
  21 {
  22   pthread_mutex_lock (&mut1);
  23
  24   do
  25     {
  26       if (--ntogo == 0)
  27         {
  28           pthread_mutex_lock (&mut2);
  29           alldone = true;
  30           pthread_cond_signal (&cond2);
  31           pthread_mutex_unlock (&mut2);
  32         }
  33
  34       pthread_cond_wait (&cond1, &mut1);
  35     }
  36   while (! last_round);
  37
  38   pthread_mutex_unlock (&mut1);
  39
  40   return NULL;
  41 }
  42
  43
  44 int
  45 main (int argc, char *argv[])
  46 {
  47   int opt;
  48   int err;
  49   int nthreads = 10;
  50   int nrounds = 100;
  51   bool keeplock = false;
  52
  53   while ((opt = getopt (argc, argv, "n:r:k")) != -1)
  54     switch (opt)
  55       {
  56       case 'n':
  57         nthreads = atol (optarg);
  58         break;
  59       case 'r':
  60         nrounds = atol (optarg);
  61         break;
  62       case 'k':
  63         keeplock = true;
  64         break;
  65       }
  66
  67   ntogo = nthreads;
  68
  69   pthread_t th[nthreads];
  70   int i;
  71   for (i = 0; i < nthreads; ++i)
  72     if (__builtin_expect ((err = pthread_create (&th[i], NULL, cons, (void *) (long) i)) != 0, 0))
  73       printf ("pthread_create: %s\n", strerror (err));
  74
  75   for (i = 0; i < nrounds; ++i)
  76     {
  77       pthread_mutex_lock (&mut2);
  78       while (! alldone)
  79         pthread_cond_wait (&cond2, &mut2);
  80       pthread_mutex_unlock (&mut2);
  81
  82       pthread_mutex_lock (&mut1);
  83       if (! keeplock)
  84         pthread_mutex_unlock (&mut1);
  85
  86       ntogo = nthreads;
  87       alldone = false;
  88       if (i + 1 >= nrounds)
  89         last_round = true;
  90
  91       pthread_cond_broadcast (&cond1);
  92
  93       if (keeplock)
  94         pthread_mutex_unlock (&mut1);
  95     }
  96
  97   for (i = 0; i < nthreads; ++i)
  98     if ((err = pthread_join (th[i], NULL)) != 0)
  99       printf ("pthread_create: %s\n", strerror (err));
 100
 101   return 0;
 102 }