Re: Detecting PREEMPT_RT

Hi Michael,

quoted

Unfortunately, this wiki article is old and unmaintained. You're probably right to be a bit suspicious when checking for the "-rt" suffix of the kernel release (uname -r). But looking for the occurrence of "PREEMPT RT" in the kernel version (uname -v) should work. An application may use the system call uname() and check the version element of the utsname structure.

the utsname.version string match is fine, however:

quoted

In addition you may want to make sure the system has high-resolution timers. If so, the timers in /proc/timer_list have ".resolution: 1 nsecs". An application may use the function check_timer() from cyclictest for this purpose:
static int check_timer(void)
{
  struct timespec ts;

  if (clock_getres(CLOCK_MONOTONIC, &ts))
    return 1;

  return (ts.tv_sec != 0 || ts.tv_nsec != 1);
}

Just tried this on a generic kernel (2.6.32-45-generic #102-Ubuntu SMP Wed Jan 2 21:53:06 UTC 2013 i686 GNU/Linux) and I get ts.tv_sec == 0 and ts.tv_nsec == 1, so it looks this cant be used to tell an RT_PREEMPT from a vanilla kernel

I meant boolean AND when I said "In addition".

	-Carsten.