Re: [Xenomai-core] latency kernel part crashes on ppc64

[Heikki Lindholm <holindho@domain.hid>]

Jan Kiszka kirjoitti:
> Heikki Lindholm wrote:
> 
>>Jan Kiszka kirjoitti:
>>
>>
>>>Heikki Lindholm wrote:
>>>
>>>
>>>>Hi,
>>>>
>>>>Some recent changes (*cough* RTDM benchmark driver *cough*) broke kernel
>>>>mode benchmarking for ppc64. Previously klatency worked fine, but now
>>>>latency -t 1 crashes somewhere in xnpod_schedule. Jan, any pending
>>>>patches a comin'?
>>>
> 
> To get this clearly: You tested the old klatency(+front-end) on latest
> xeno and it worked? Or does this parse "the old klatency worked over old
> xeno on PPC64"?
> 
> Comparing the old test with the new framework, the major difference is
> that the old one only knew a single kernel RT-task. Its front-end was
> reading from a pipe and was therefore a pure linux program. Now we have
> two RT-tasks, one is even a shadow, and they use RT-IPC. Not sure if
> this really means that the bug must be in the benchmark suite...
> 
> 
>>>
>>>Nope, it should work as it is. But as Stelian also reported problems on
>>>his fresh ARM port with the in-kernel test, I cannot exclude that there
>>>/might/ be a problem in the benchmark.
>>>
>>>As I don't have any ppc64 hanging around somewhere, we will have to go
>>>through this together. Things I would like to know:
>>
>>
>>Dammit, I hoped you'd whip up a fix just from me noting a problem. Well,
>>all right then, I'll play along...;)
>>
>>
>>> o When and how does it crash? At start-up immediately? Or after a
>>>   while?
>>
>>
>>I inserted some serial debug prints and it gets two passes to
>>eval_outer_loop done (enter/exit function). After that it freezes.
>>Without the debug printing it dies with kernel access of illegal memory
>>at xnpod_schedule, which btw. has been quite a common place to die.
>>
>>
>>> o Are there any details / backtraces available with the crash?
>>
>>
>>Becaktrace limits to xnpod_schedule if I remember right.
>>
>>
>>> o Does -t2 work?
>>
>>
>>Umm. Probably not. See below.
> 
> 
> Arrgh, "probably" - when it's so easy to test...

Shoot! The "probably" operator was incorrect, "-t 2" did work.

-- hl