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           alldone = true;
  29           pthread_cond_signal (&cond2);
  30         }
  31
  32       pthread_cond_wait (&cond1, &mut1);
  33     }
  34   while (! last_round);
  35
  36   pthread_mutex_unlock (&mut1);
  37
  38   return NULL;
  39 }
  40
  41
  42 int
  43 main (int argc, char *argv[])
  44 {
  45   int opt;
  46   int err;
  47   int nthreads = 10;
  48   int nrounds = 100;
  49   bool keeplock = false;
  50
  51   while ((opt = getopt (argc, argv, "n:r:k")) != -1)
  52     switch (opt)
  53       {
  54       case 'n':
  55         nthreads = atol (optarg);
  56         break;
  57       case 'r':
  58         nrounds = atol (optarg);
  59         break;
  60       case 'k':
  61         keeplock = true;
  62         break;
  63       }
  64
  65   ntogo = nthreads;
  66
  67   pthread_t th[nthreads];
  68   int i;
  69   for (i = 0; i < nthreads; ++i)
  70     if ((err = pthread_create (&th[i], NULL, cons, (void *) (long) i)) != 0)
  71       printf ("pthread_create: %s\n", strerror (err));
  72
  73   for (i = 0; i < nrounds; ++i)
  74     {
  75       pthread_mutex_lock (&mut2);
  76       while (! alldone)
  77         pthread_cond_wait (&cond2, &mut2);
  78       pthread_mutex_unlock (&mut2);
  79
  80       pthread_mutex_lock (&mut1);
  81       if (! keeplock)
  82         pthread_mutex_unlock (&mut1);
  83
  84       ntogo = nthreads;
  85       alldone = false;
  86       if (i + 1 >= nrounds)
  87         last_round = true;
  88
  89       pthread_cond_broadcast (&cond1);
  90
  91       if (keeplock)
  92         pthread_mutex_unlock (&mut1);
  93     }
  94
  95   for (i = 0; i < nthreads; ++i)
  96     if ((err = pthread_join (th[i], NULL)) != 0)
  97       printf ("pthread_create: %s\n", strerror (err));
  98
  99   return 0;
 100 }