rt/tst-cputimer1.c

   1 /* Tests for POSIX timer implementation using process CPU clock.  */
   2
   3 #include <unistd.h>
   4
   5 #if _POSIX_THREADS && defined _POSIX_CPUTIME
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <fcntl.h>
  11 #include <time.h>
  12 #include <pthread.h>
  13
  14 #define TEST_CLOCK CLOCK_PROCESS_CPUTIME_ID
  15 #define TEST_CLOCK_MISSING(clock) \
  16   (setup_test () ? "process CPU clock timer support" : NULL)
  17
  18 /* This function is intended to rack up both user and system time.  */
  19 static void *
  20 chew_cpu (void *arg)
  21 {
  22   while (1)
  23     {
  24       static volatile char buf[4096];
  25       for (int i = 0; i < 100; ++i)
  26         for (size_t j = 0; j < sizeof buf; ++j)
  27           buf[j] = 0xaa;
  28       int nullfd = open ("/dev/null", O_WRONLY);
  29       for (int i = 0; i < 100; ++i)
  30         for (size_t j = 0; j < sizeof buf; ++j)
  31           buf[j] = 0xbb;
  32       write (nullfd, (char *) buf, sizeof buf);
  33       close (nullfd);
  34     }
  35
  36   return NULL;
  37 }
  38
  39 static int
  40 setup_test (void)
  41 {
  42   /* Test timers on our own process CPU clock by having a worker thread
  43      eating CPU.  First make sure we can make such timers at all.  */
  44
  45   timer_t t;
  46   if (timer_create (TEST_CLOCK, NULL, &t) != 0)
  47     {
  48       printf ("timer_create: %m\n");
  49       return 1;
  50     }
  51   timer_delete (t);
  52
  53   pthread_t th;
  54   int e = pthread_create (&th, NULL, chew_cpu, NULL);
  55   if (e != 0)
  56     {
  57       printf ("pthread_create: %s\n", strerror (e));
  58       exit (1);
  59     }
  60
  61   return 0;
  62 }
  63
  64 #else
  65 # define TEST_CLOCK_MISSING(clock) "process clocks"
  66 #endif
  67
  68 #include "tst-timer4.c"