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 #include <atomic.h>
   8
   9 static pthread_cond_t cond1 = PTHREAD_COND_INITIALIZER;
  10 static pthread_mutex_t mut1 = PTHREAD_MUTEX_INITIALIZER;
  11
  12 static pthread_cond_t cond2 = PTHREAD_COND_INITIALIZER;
  13 static pthread_mutex_t mut2 = PTHREAD_MUTEX_INITIALIZER;
  14
  15 static bool last_round;
  16 static int ntogo;
  17 static bool alldone;
  18
  19
  20 static void *
  21 cons (void *arg)
  22 {
  23   pthread_mutex_lock (&mut1);
  24
  25   do
  26     {
  27       if (atomic_decrement_and_test (&ntogo))
  28         {
  29           pthread_mutex_lock (&mut2);
  30           alldone = true;
  31           pthread_cond_signal (&cond2);
  32           pthread_mutex_unlock (&mut2);
  33         }
  34
  35       pthread_cond_wait (&cond1, &mut1);
  36     }
  37   while (! last_round);
  38
  39   pthread_mutex_unlock (&mut1);
  40
  41   return NULL;
  42 }
  43
  44
  45 int
  46 main (int argc, char *argv[])
  47 {
  48   int opt;
  49   int err;
  50   int nthreads = 10;
  51   int nrounds = 100;
  52   bool keeplock = false;
  53
  54   while ((opt = getopt (argc, argv, "n:r:k")) != -1)
  55     switch (opt)
  56       {
  57       case 'n':
  58         nthreads = atol (optarg);
  59         break;
  60       case 'r':
  61         nrounds = atol (optarg);
  62         break;
  63       case 'k':
  64         keeplock = true;
  65         break;
  66       }
  67
  68   ntogo = nthreads;
  69
  70   pthread_t th[nthreads];
  71   int i;
  72   for (i = 0; __builtin_expect (i < nthreads, 1); ++i)
  73     if (__glibc_unlikely ((err = pthread_create (&th[i], NULL, cons, (void *) (long) i)) != 0))
  74       printf ("pthread_create: %s\n", strerror (err));
  75
  76   for (i = 0; __builtin_expect (i < nrounds, 1); ++i)
  77     {
  78       pthread_mutex_lock (&mut2);
  79       while (! alldone)
  80         pthread_cond_wait (&cond2, &mut2);
  81       pthread_mutex_unlock (&mut2);
  82
  83       pthread_mutex_lock (&mut1);
  84       if (! keeplock)
  85         pthread_mutex_unlock (&mut1);
  86
  87       ntogo = nthreads;
  88       alldone = false;
  89       if (i + 1 >= nrounds)
  90         last_round = true;
  91
  92       pthread_cond_broadcast (&cond1);
  93
  94       if (keeplock)
  95         pthread_mutex_unlock (&mut1);
  96     }
  97
  98   for (i = 0; i < nthreads; ++i)
  99     if ((err = pthread_join (th[i], NULL)) != 0)
 100       printf ("pthread_create: %s\n", strerror (err));
 101
 102   return 0;
 103 }