[etherlab-users] R: System randomly freezes in multi-thread Qt application with a RT process

Viola Roberto Mon, 27 May 2019 01:58:20 -0700

Hi Simone,
  from the logs it seems a issue releated to your i915 (video card, i guess 
inside your CPU).
You should try to understand the cause of issue: i suggest to try without the 
ethercat and stressing the cpu and the video card in some other way. I guess 
it’s not related to ethercat.
BTW what videocard do you have?
Did you try to catch the logs on other systems (laptop for example)?
R.

Da: Simone Comari [mailto:simone.coma...@unibo.it]
Inviato: giovedì 23 maggio 2019 12:51
A: Viola Roberto <roberto.vi...@systemceramics.com>; etherlab-users@etherlab.org
Oggetto: R: System randomly freezes in multi-thread Qt application with a RT
process

Hi Roberto,

First of all, thank you for your quick response.
Attached you can find the kernel.log and system.log of a single session, that
is:

1. Boot up
2. Application launch (successful ethercat network setup) through Qt IDE
3. Successful enabling of a single motor (i.e. one of the ethercat slaves)
through our GUI
4. Simple operation (e.g. manual velocity control) until problem occurs (it
took a couple of minutes this time)
5. Hard shut-down of the "frozen" system
I hope these are the logs you were talking about, please let me know otherwise.

Maybe it's worth mentioning we followed
these<https://github.com/UNIBO-GRABLab/cable_robot/wiki/Installation>
instructions to install both the RT kernel and ethercat libs, just in case we
misused patches or configurations.

Thanks again.

Best regards,
Simone

Roberto Viola
Technical Dept
+39 0536836680

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________________________________
Da: Viola Roberto
<roberto.vi...@systemceramics.com<mailto:roberto.vi...@systemceramics.com>>
Inviato: giovedì 23 maggio 2019 08:00
A: Simone Comari;
etherlab-users@etherlab.org<mailto:etherlab-users@etherlab.org>
Oggetto: R: System randomly freezes in multi-thread Qt application with a RT
process

Hi Simone, just a quick hint in order to understand the freeze: try to run the
setup inside a VM (kvm or virtualbox) in order to catch the serial log from the
kernel or, if you have a UART avaiable on your system, directly from it.

In this way we should try to understand the issue better.

Da: etherlab-users [mailto:etherlab-users-boun...@etherlab.org] Per conto di
Simone Comari
Inviato: mercoledì 22 maggio 2019 18:52
A: etherlab-users@etherlab.org<mailto:etherlab-users@etherlab.org>
Oggetto: [etherlab-users] System randomly freezes in multi-thread Qt
application with a RT process

Hi all,

I am a young research fellow at the university of Bologna and I just started
working with EtherCAT technology and RT systems yet, so please forgive me if I
misuse words or I'm not precise enough.

First, I'll try to describe my setup:

* Ubuntu 16.04.6 with patched fully preemptible RT kernel 4.13.13-rt5
* Qt 5.12.2
* PCI driver e1000e
* Ethercat master running on this Linux RT
* Elmo GOLD SOLO WHISTLE Drives (ethercat slaves)

Secondly, a brief outline of my software architecture:

* POSIX threads
* Qt-based GUI running on a non-RT thread
* Ethercat network setup (ethercat master and slaves init) done in the same
non-RT thread
* If initialization is successful, start a new RT-thread in charge of
handling all ethercat-related functionalities (read/write/status-check).
* Shared resources between RT and non-RT ones handled with pthread_mutex
(even if I'm not 100% sure I'm using it correctly)
* Implementation of our generic ethercat master can be found
here<https://github.com/UNIBO-GRABLab/grab_common/blob/e5278b6fe611654bfa84c951d8b77e56ebbc8fa9/libgrabec/src/ethercatmaster.cpp>

Problem description:

* Once the ethercat network is setup and the RT thread is started, quite
randomly the system freezes without errors of any sorts. Sometimes it happens
when motors are enabled and operational, sometimes when they are enabled and
idle, sometimes even if they are disabled. It is not reproducible and I
couldn't link it to any particular step in my application. Sometimes it happens
even if I simply start it, but always after successful initialization.
* Even when I manage to close the application, next time I try to run it it
tells me that master is busy and ec_e1000e is in use. Only solution is to
manually hard-shut-down the PC.
* Other thing I noticed is that even if the main thread (the GUI one, so
non-RT) is closed, the child RT-thread stays running with status D
(uninterruptible sleep) blocking a great deal of CPU (that is why probably the
whole system freezes).
* We tried with different computers (both laptop and desktop) to exclude a
platform's dependency, but the issue remains.

Please let me know if there is any missing important information that can help
understanding the problem.

Thank you a lot for the support.

Best regards,

Simone
Roberto Viola

Technical Dept

+39 0536836680

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SYSTEM CERAMICS S.p.A.

Via Ghiarola Vecchia, 73

41042 Fiorano (Mo) ITALY

+39 0536 836111

i...@system-electronics.it<mailto:i...@system-electronics.it>

www.system-electronics.it<http://www.system-electronics.it>

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