Re: [Xenomai-help] [RTnet-users] Ideas how to measure delays with RTnet

[Jan Kiszka <jan.kiszka@domain.hid>]

Karl Reichert wrote:
> Jan Kiszka wrote:
>> Karl Reichert wrote:
>>> Hello,
>>>
>>> I have two stations running RTnet, one as a master and one as a slave. I
>> want 
>>> to measure the time, which a message, sent from master to slave, takes.
>> But, 
>>> I don't want the time of the transmission only, but the complete time of
>> all 
>>> software layers this data is processed through.
>>>
>>> _______________	_______________
>>> |		A		  |	|		D		  |
>>> |______________|	|______________|
>>> |		B		  |	|		C		  |
>>> |______________|	|______________|
>>> |   RTnet (Master)	  |	|    RTnet (Slave)	  |
>>> |______________|	|______________|
>>> 		|				  |
>>> 		|______________|
>>>
>>> So, I create the data, that should be send, in Layer A (Master) and send
>> it 
>>> over RTnet to Layer D (Slave).
>>>
>>> I want to take the time when the data leaves A and when it arrives D
>> with 
>>> rtdm_clock_read(). If I have the offset between master and slave, I can 
>>> calculate the time it took to pass A, B, both RTnet stacks, C and D.
>>>
>>> As RTnet keeps track of the offset in it's stack, I want to use this
>> value. Is 
>>> it possible via the API? I didn't found anything. Or do I have to
>> manipulate 
>>> the stack to pass the offset to the higher layers (C and D)?
>> If RTmac/TDMA is in use, you can obtain the clock offset via
>> RTMAC_RTIOC_TIMEOFFSET from the RTDM device "TDMA<x>" (where "<x>"
>> corresponds to "rteth<x>").
>>
>> Jan
>>
> 
> When I try to compile my application (xenomai native skin, user task), I get an error, saying rtdm_driver.h (which contains the prototype for rtdm_clock_read()) is for kernel mode tasks only.

So you are in userland, obviously...

> 
> How can I get a timestamp in a xenomai native user task? Is there sth equivalent to rtdm_clock_read()? Or do I have to write a kernel task?

Nope, there is rt_timer_read & Co. for native user-mode applications.

I was about to remark that everything can be found in the API docs - but
it can't! Any volunteer to add the missing functions from native/timer.h
to the docs? Maybe there is just something broken for doxygen. TIA!

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux