On 02/28/2013 09:22 PM, Thomas De Schampheleire wrote:
> On Thu, Feb 28, 2013 at 9:10 PM, Gilles Chanteperdrix
> <[email protected]> wrote:
>> On 02/28/2013 08:19 PM, Ronny Meeus wrote:
>>
>>> Hello
>>>
>>> we are using the PSOS interface of Xenomai forge, running completely
>>> in user-space using the mercury code.
>>> We deploy our application on different processors, one product is
>>> running on PPC multicore (P4040, P4080, P4034) and another one on
>>> Cavium (8 core device).
>>> The Linux version we use is 2.6.32 but I would assume that this is not
>>> so relevant.
>>>
>>> Our Xenomai application is running on one of the cores (affinity is
>>> set), while the other cores are running other code.
>>>
>>> On both architectures we recently start to see issues that one thread
>>> is consuming 100% of the core on which the application is pinned.
>>> The thread that monopolizes the core is the thread internally used to
>>> manage the timers, running at the highest priority.
>>> The trigger for running into this behavior is currently unclear.
>>> If we only start a part of the application (platform management only),
>>> the issue is not observed.
>>> We see this on both an old version of Xenomai and a very recent one
>>> (pulled from the git repo yesterday).
>>>
>>> I will continue to debug this issue in the coming days and try isolate
>>> the code that is triggering it, but I can use hints from the
>>> community.
>>> Debugging is complex since once the load starts, the debugger is not
>>> reacting anymore.
>>> If I put breakpoints in the functions that are called when the timer
>>> expires (both oneshot and periodic), the process starts to clone
>>> itself and I endup with tens of them.
>>>
>>> Has anybody seen an issue like this before or does somebody has some
>>> hints on how to debug this problem?
>>
>>
>> First enable the watchdog. It will send a signal to the application when
>> detecting a problem, then you can use the watchdog to trigger an I-pipe
>> tracer trace when the bug happens. You will probably have to increase
>> the watchdog polling frequency, in order to have a meaningful trace.
>>
>
> I don't think an I-pipe tracer will be possible when using the Mercury
> core, right (xenomai-forge) ?
As the name indicates the "I-PIPE tracer" has nothing to do with the
version of Xenomai you use. Anyway, you can firs try to trigger a
backtrace when the watchdog sends its signal, in case the bug is in the
application and not in the kernel. You never know...
--
Gilles.
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