On 25.02.19 17:57, Ari Mozes via Xenomai wrote:
Philippe,
Thank you for the information and the URL.
I read through the thread, and I agree with comments that it would be
helpful to be able to identify/blacklist/etc problematic calls when
porting over existing code to a true RT scenario. In our case the
original code was written with "RT-like" behavior in mind, but as
there is a lot of code already in place, approaches to identify
existing problematic calls would be helpful.
You could wrap such calls like we do for malloc/free in libcobalt. But wrapping
only works if the direct caller is processed that way - and is not some
pre-built external library.
Therefore: Do not use libraries that you didn't validate from within
time-sensitive code paths. Also libstdc++ may contain more surprises.
Jan
I will continue to familiarize myself with the nitty-gritty details,
but anything that makes the process easier is always welcome :-)
Ari
On Mon, Feb 25, 2019 at 11:08 AM Philippe Gerum <[email protected]> wrote:
On 2/25/19 2:32 PM, Ari Mozes via Xenomai wrote:
Resending this question with testcase.
Can someone give the testcase a try to see if it reproduces the problem I
am seeing? Is more information needed?
It takes a couple of minutes before I see the issue occur.
The random lockup is due to std::chrono::high_resolution_clock::now()
invoking the vDSO form of clock_gettime().
SIGXCPU aka Xenomai's SIGDEBUG may be sent by the core in various
situations, but since the code does not set the T_WARNSW for any task,
the only explanation is receiving a Xenomai watchdog notification. See
the help information about CONFIG_XENO_OPT_WATCHDOG in your kernel
configuration.
After a few secs spinning in the vDSO code which may not be called from
real-time context, the Xenomai core pulls the break and sends SIGXCPU to
the offending process, unless the system locks up before the watchdog
could even trigger.
Solution: use clock_gettime(CLOCK_HOST_REALTIME) instead of
std::chrono::high_resolution_clock::now() for getting timestamps.
A related discussion is available at this URL:
https://www.xenomai.org/pipermail/xenomai/2018-December/040133.html
--
Philippe.
--
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Corporate Competence Center Embedded Linux
