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 #include <support/xunistd.h>
  15
  16 #define TEST_CLOCK CLOCK_PROCESS_CPUTIME_ID
  17 #define TEST_CLOCK_MISSING(clock) \
  18   (setup_test () ? "process CPU clock timer support" : NULL)
  19
  20 /* This function is intended to rack up both user and system time.  */
  21 static void *
  22 chew_cpu (void *arg)
  23 {
  24   while (1)
  25     {
  26       static volatile char buf[4096];
  27       for (int i = 0; i < 100; ++i)
  28         for (size_t j = 0; j < sizeof buf; ++j)
  29           buf[j] = 0xaa;
  30       int nullfd = open ("/dev/null", O_WRONLY);
  31       for (int i = 0; i < 100; ++i)
  32         for (size_t j = 0; j < sizeof buf; ++j)
  33           buf[j] = 0xbb;
  34       xwrite (nullfd, (char *) buf, sizeof buf);
  35       close (nullfd);
  36     }
  37
  38   return NULL;
  39 }
  40
  41 static int
  42 setup_test (void)
  43 {
  44   /* Test timers on our own process CPU clock by having a worker thread
  45      eating CPU.  First make sure we can make such timers at all.  */
  46
  47   timer_t t;
  48   if (timer_create (TEST_CLOCK, NULL, &t) != 0)
  49     {
  50       printf ("timer_create: %m\n");
  51       return 1;
  52     }
  53   timer_delete (t);
  54
  55   pthread_t th;
  56   int e = pthread_create (&th, NULL, chew_cpu, NULL);
  57   if (e != 0)
  58     {
  59       printf ("pthread_create: %s\n", strerror (e));
  60       exit (1);
  61     }
  62
  63   return 0;
  64 }
  65
  66 #else
  67 # define TEST_CLOCK_MISSING(clock) "process clocks"
  68 #endif
  69
  70 #include "tst-timer4.c"