Attachment 936152 Details for Bug 1064059 – Reduced test case

Reduced test case

tst-cpuclock2.c (text/plain), 3.58 KB, created by Siddhesh Poyarekar on 2014-09-10 13:30:08 UTC

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Creator: Siddhesh Poyarekar

Created: 2014-09-10 13:30:08 UTC

Size: 3.58 KB

patch

obsolete

>#define _GNU_SOURCE
>#include <unistd.h>
>#include <sys/syscall.h>
>#include <stdio.h>
>#include <time.h>
>#include <pthread.h>
>#include <stdint.h>
>#include <inttypes.h>
>
>/* Parameters for the Linux kernel ABI for CPU clocks.  */
>
>#define CPUCLOCK_PID(clock)             ((pid_t) ~((clock) >> 3))
>#define CPUCLOCK_PERTHREAD(clock) \
>        (((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)
>#define CPUCLOCK_PID_MASK       7
>#define CPUCLOCK_PERTHREAD_MASK 4
>#define CPUCLOCK_WHICH(clock)   ((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
>#define CPUCLOCK_CLOCK_MASK     3
>#define CPUCLOCK_PROF           0
>#define CPUCLOCK_VIRT           1
>#define CPUCLOCK_SCHED          2
>#define CPUCLOCK_MAX            3
>
>#define MAKE_PROCESS_CPUCLOCK(pid, clock) \
>        ((~(clockid_t) (pid) << 3) | (clockid_t) (clock))
>#define MAKE_THREAD_CPUCLOCK(tid, clock) \
>        MAKE_PROCESS_CPUCLOCK((tid), (clock) | CPUCLOCK_PERTHREAD_MASK)
>
>
>static pthread_barrier_t barrier;
>
>/* Help advance the clock.  */
>static void *
>chew_cpu (void *arg)
>{
>  pthread_barrier_wait (&barrier);
>  while (1);
>
>  return NULL;
>}
>
>/* Don't use the glibc wrapper.  */
>static int
>do_nanosleep (int flags, const struct timespec *req)
>{
>  clockid_t clock_id = MAKE_PROCESS_CPUCLOCK (0, CPUCLOCK_SCHED);
>
>  return syscall (SYS_clock_nanosleep, clock_id, flags, req, NULL);
>}
>
>static int64_t
>tsdiff (const struct timespec *before, const struct timespec *after)
>{
>  int64_t before_i = before->tv_sec * 1000000000ULL + before->tv_nsec;
>  int64_t after_i = after->tv_sec * 1000000000ULL + after->tv_nsec;
>
>  return after_i - before_i;
>}
>
>int
>main (void)
>{
>  int result = 0;
>  pthread_t th;
>
>  pthread_barrier_init (&barrier, NULL, 2);
>
>  if (pthread_create (&th, NULL, chew_cpu, NULL) != 0)
>    {
>      perror ("pthread_create");
>      return 1;
>    }
>
>  pthread_barrier_wait (&barrier);
>
>  /* The test.  */
>  struct timespec before, after, sleeptimeabs;
>  int64_t sleepdiff, diffabs;
>  const struct timespec sleeptime = { .tv_sec = 0, .tv_nsec = 100000000 };
>
>  /* The relative nanosleep.  Not sure why this is needed, but its presence
>     seems to make it easier to reproduce the problem.  */
>  if (do_nanosleep (0, &sleeptime) != 0)
>    {
>      perror ("clock_nanosleep");
>      return 1;
>    }
>
>  /* Get the current time.  */
>  if (clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &before) < 0)
>    {
>      perror ("clock_gettime[2]");
>      return 1;
>    }
>
>  /* Compute the absolute sleep time based on the current time.  */
>  uint64_t nsec = before.tv_nsec + sleeptime.tv_nsec;
>  sleeptimeabs.tv_sec = before.tv_sec + nsec / 1000000000;
>  sleeptimeabs.tv_nsec = nsec % 1000000000;
>
>  /* Sleep for the computed time.  */
>  if (do_nanosleep (TIMER_ABSTIME, &sleeptimeabs) != 0)
>    {
>      perror ("absolute clock_nanosleep");
>      return 1;
>    }
>
>  /* Get the time after the sleep.  */
>  if (clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &after) < 0)
>    {
>      perror ("clock_gettime[3]");
>      return 1;
>    }
>
>  /* The time after sleep should always be equal to or after the absolute sleep
>     time passed to clock_nanosleep.  */
>  sleepdiff = tsdiff (&sleeptimeabs, &after);
>  if (sleepdiff < 0)
>    {
>      printf ("absolute clock_nanosleep woke too early: %" PRId64 "\n",
>	      sleepdiff);
>      result = 1;
>    }
>
>  /* The difference between the timestamps taken before and after the
>     clock_nanosleep call should be equal to or more than the duration of the
>     sleep.  */
>  diffabs = tsdiff (&before, &after);
>  if (diffabs < sleeptime.tv_nsec)
>    {
>      printf ("clock_gettime difference too small: %" PRId64 "\n", diffabs);
>      result = 1;
>    }
>
>  pthread_cancel (th);
>
>  return result;
>}

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Attachments on bug 1064059: 936152