From: Michael Haberler <mail17@mah.priv.at>
To: Carsten Emde <C.Emde@osadl.org>
Cc: John Morris <john@zultron.com>, linux-rt-users@vger.kernel.org
Subject: Re: Detecting PREEMPT_RT
Date: Sun, 20 Jan 2013 16:52:51 +0100 [thread overview]
Message-ID: <1819DC75-5826-4882-A2B7-20953DE3392A@mah.priv.at> (raw)
In-Reply-To: <50FB4BB1.7070005@osadl.org>
Hi Carsten
Am 20.01.2013 um 02:43 schrieb Carsten Emde:
> 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:
> 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
- Michael
next prev parent reply other threads:[~2013-01-20 15:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-20 0:13 Detecting PREEMPT_RT John Morris
2013-01-20 1:43 ` Carsten Emde
2013-01-20 15:52 ` Michael Haberler [this message]
2013-01-20 17:32 ` Carsten Emde
2013-01-20 18:39 ` John Morris
2013-01-20 20:18 ` Carsten Emde
2013-01-21 11:36 ` John Kacur
2013-01-21 12:14 ` Michael Haberler
2013-01-21 12:17 ` John Kacur
2013-01-22 10:47 ` Michael Haberler
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