static int
do_test (void)
{
int result = 0;
clockid_t cl;
int e;
pid_t dead_child, child;
/* Fork a child and let it die, to give us a PID known not be valid
(assuming PIDs don't wrap around during the test). */
{
dead_child = fork ();
if (dead_child == 0)
_exit (0);
if (dead_child < 0)
{
perror ("fork");
return 1;
}
int x;
if (wait (&x) != dead_child)
{
perror ("wait");
return 2;
}
}
/* POSIX says we should get ESRCH for this. */
e = clock_getcpuclockid (dead_child, &cl);
if (e != ENOSYS && e != ESRCH && e != EPERM)
{
printf ("clock_getcpuclockid on dead PID %d => %s\n",
dead_child, strerror (e));
result = 1;
}
/* Now give us a live child eating up CPU time. */
child = fork ();
if (child == 0)
{
chew_cpu ();
_exit (1);
}
if (child < 0)
{
perror ("fork");
return 1;
}
e = clock_getcpuclockid (child, &cl);
if (e == EPERM)
{
puts ("clock_getcpuclockid does not support other processes");
goto done;
}
if (e != 0)
{
printf ("clock_getcpuclockid on live PID %d => %s\n",
child, strerror (e));
result = 1;
goto done;
}
const clockid_t child_clock = cl;
struct timespec res;
if (clock_getres (child_clock, &res) < 0)
{
printf ("clock_getres on live PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
result = 1;
goto done;
}
printf ("live PID %d clock %lx resolution %ju.%.9ju\n",
child, (unsigned long int) child_clock,
(uintmax_t) res.tv_sec, (uintmax_t) res.tv_nsec);
struct timespec before, after;
if (clock_gettime (child_clock, &before) < 0)
{
printf ("clock_gettime on live PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
result = 1;
goto done;
}
/* Should be close to 0.0. */
printf ("live PID %d before sleep => %ju.%.9ju\n",
child, (uintmax_t) before.tv_sec, (uintmax_t) before.tv_nsec);
struct timespec sleeptime = { .tv_nsec = 500000000 };
if (nanosleep (&sleeptime, NULL) != 0)
{
perror ("nanosleep");
result = 1;
goto done;
}
if (clock_gettime (child_clock, &after) < 0)
{
printf ("clock_gettime on live PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
result = 1;
goto done;
}
/* Should be close to 0.5. */
printf ("live PID %d after sleep => %ju.%.9ju\n",
child, (uintmax_t) after.tv_sec, (uintmax_t) after.tv_nsec);
struct timespec diff = { .tv_sec = after.tv_sec - before.tv_sec,
.tv_nsec = after.tv_nsec - before.tv_nsec };
if (diff.tv_nsec < 0)
{
--diff.tv_sec;
diff.tv_nsec += 1000000000;
}
if (diff.tv_sec != 0
|| diff.tv_nsec > 600000000
|| diff.tv_nsec < 100000000)
{
printf ("before - after %ju.%.9ju outside reasonable range\n",
(uintmax_t) diff.tv_sec, (uintmax_t) diff.tv_nsec);
result = 1;
}
sleeptime.tv_nsec = 100000000;
e = clock_nanosleep (child_clock, 0, &sleeptime, NULL);
if (e == EINVAL || e == ENOTSUP || e == ENOSYS)
{
printf ("clock_nanosleep not supported for other process clock: %s\n",
strerror (e));
}
else if (e != 0)
{
printf ("clock_nanosleep on other process clock: %s\n", strerror (e));
result = 1;
}
else
{
struct timespec afterns;
if (clock_gettime (child_clock, &afterns) < 0)
{
printf ("clock_gettime on live PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
result = 1;
}
else
{
struct timespec d = { .tv_sec = afterns.tv_sec - after.tv_sec,
.tv_nsec = afterns.tv_nsec - after.tv_nsec };
if (d.tv_nsec < 0)
{
--d.tv_sec;
d.tv_nsec += 1000000000;
}
if (d.tv_sec > 0
|| d.tv_nsec < sleeptime.tv_nsec
|| d.tv_nsec > sleeptime.tv_nsec * 2)
{
printf ("nanosleep time %ju.%.9ju outside reasonable range\n",
(uintmax_t) d.tv_sec, (uintmax_t) d.tv_nsec);
result = 1;
}
}
}
if (kill (child, SIGKILL) != 0)
{
perror ("kill");
result = 2;
goto done;
}
/* Wait long enough to let the child finish dying. */
sleeptime.tv_nsec = 200000000;
if (nanosleep (&sleeptime, NULL) != 0)
{
perror ("nanosleep");
result = 1;
goto done;
}
struct timespec dead;
if (clock_gettime (child_clock, &dead) < 0)
{
printf ("clock_gettime on dead PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
result = 1;
goto done;
}
/* Should be close to 0.6. */
printf ("dead PID %d => %ju.%.9ju\n",
child, (uintmax_t) dead.tv_sec, (uintmax_t) dead.tv_nsec);
diff.tv_sec = dead.tv_sec - after.tv_sec;
diff.tv_nsec = dead.tv_nsec - after.tv_nsec;
if (diff.tv_nsec < 0)
{
--diff.tv_sec;
diff.tv_nsec += 1000000000;
}
if (diff.tv_sec != 0 || diff.tv_nsec > 200000000)
{
printf ("dead - after %ju.%.9ju outside reasonable range\n",
(uintmax_t) diff.tv_sec, (uintmax_t) diff.tv_nsec);
result = 1;
}
/* Now reap the child and verify that its clock is no longer valid. */
{
int x;
if (waitpid (child, &x, 0) != child)
{
perror ("waitpid");
result = 1;
}
}
if (clock_gettime (child_clock, &dead) == 0)
{
printf ("clock_gettime on reaped PID %d clock %lx => %ju%.9ju\n",
child, (unsigned long int) child_clock,
(uintmax_t) dead.tv_sec, (uintmax_t) dead.tv_nsec);
result = 1;
}
else
{
if (errno != EINVAL)
result = 1;
printf ("clock_gettime on reaped PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
}
if (clock_getres (child_clock, &dead) == 0)
{
printf ("clock_getres on reaped PID %d clock %lx => %ju%.9ju\n",
child, (unsigned long int) child_clock,
(uintmax_t) dead.tv_sec, (uintmax_t) dead.tv_nsec);
result = 1;
}
else
{
if (errno != EINVAL)
result = 1;
printf ("clock_getres on reaped PID %d clock %lx => %s\n",
child, (unsigned long int) child_clock, strerror (errno));
}
return result;
done:
{
if (kill (child, SIGKILL) != 0 && errno != ESRCH)
{
perror ("kill");
return 2;
}
int x;
if (waitpid (child, &x, 0) != child && errno != ECHILD)
{
perror ("waitpid");
return 2;
}
}
return result;
}
static void
spam_io(size_t ticks)
{
int fd = open("/dev/null", O_WRONLY);
ssize_t i;
for (i = ticks - 1; i >= 0; --i) {
arm_desched_notification();
#if 0
sched_yield();
#elif 1
/* This is very very unlikely to desched us. */
//write(fd, i ? "." : "\n", 1);
write(STDOUT_FILENO, i ? "." : "\n", 1);
#elif 0
/* This has to desched us. */
system("sleep 1");
#else
struct timespec req = { .tv_sec = 1, .tv_nsec = 0 };
struct timespec rem;
nanosleep(&req, &rem);
#endif
disarm_desched_notification();
}
close(fd);
}
static void
child()
{
debug("child: execution info:\n"
" child() = %p\n"
" nr_switches = %u",
child,
nr_switches);
if (IO == which) {
debug(" spam_io() = %p, %u ticks", spam_io, io_ticks);
} else {
debug(" chew_cpu() = %p, %u ticks", chew_cpu, cpu_ticks);
}
counter_fd = open_counter(nr_switches);
send_fd(counter_fd, child_socket);
debug("child accepting ptrace");
ptrace(PTRACE_TRACEME, 0, 0, 0);
raise(SIGSTOP);
if (CPU == which) {
chew_cpu(cpu_ticks);
} else if (IO == which) {
spam_io(io_ticks);
} else {
*((volatile int*)0) = 42;
}
_exit(0);
}