在2009-12-30，"Gilles Chanteperdrix" <gilles.chanteperdrix@xenomai.org> 写道：
>robert165 wrote:
>> 
>> 
>> 
>> 在2009-12-29，"Gilles Chanteperdrix" <gilles.chanteperdrix@xenomai.org> 写道：
>>>robert165 wrote:
>>>> 
>>>> 
>>>> 
>>>> 在2009-12-28，"Gilles Chanteperdrix" <gilles.chanteperdrix@xenomai.org> 写道：
>>>>>robert165 wrote:
>>>>>> Hi,
>>>>>> I have tested xenomai on my at91rm9200 board, I used
>>>>>> xenomai 2.4.10 + linux-2.6.28 + adeos-ipipe-2.6.28-arm-1.12-05.patch
>>>>>> Test result seems very poor, is that correct?
>>>>>
>>>>>Your test results are rather good for an at91rm9200 board, which is the
>>>>>sure sign that you are not loading the system enough.
>>>>>
>>>>>As I already told, you, the expected results are:
>>>>>- user-space latency of 260us without FCSE
>>>>>- user-space latency of 200us with FCSE
>>>>>- kernel-space latency of 50us if running with unlocked context switches
>>>>>(an option which is only available in the upcoming 2.5 branch).
>>>>>
>>>>>> And is there any introduction of the tests, as their purper, their
>>>>>> meanling...
>>>>>
>>>>>The latency test computes some latencies (either user-space scheduling
>>>>>latency, kernel-space scheduling latency, or kernel-space interrupt
>>>>>latency, depending on the options). The switchtest tests context
>>>>>switches. The switchbench measures context switching time. cyclictest
>>>>>does the same thing as the latency test (only, you need to run it with
>>>>>the right options to avoid running in fact with Linux timer), and in
>>>>>general return similar results. Here I do not know what is the meaning
>>>>>of cyclictest results you got, but if you want to know, I am afraid you
>>>>>wil have to investigate, or simply ignore them.
>>>>>
>>>> 
>>>> Thanks for your introdution, and is there any document of it. 
>>>> The man pages just explain  parametres  of test scripts.  I could
>>>> not understand the output of some test.
>>>
>>>No there is no document. But patches are welcome, as usual. As far as I
>>>can tell, I explained you what the tests do, there is not much more to
>>>tell. Which test's output did you not understand?
>>>
>> 
>> when running: ./run -- -p 1000 -T 180 -t2 # latency
>> result gave negative numbers like 
>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
>> RTD|      -3.739|      11.330|      39.530|       0|      -3.739|      39.530
>> Is that means timer interrupts are not perfect, and may occur before or after the exact moment.
>> If so, the avg should calculate by the absolute value of the latency, and the best should be 
>> the least absolute value.
>
>It is a matter of point of view. From our point of view, the timer
>interrupt ticking in advance is a feature, it compensates a bit for the
>latency. Anyway, if you do not like it, just
>echo 0 > /proc/xenomai/latency
>
>The timer interrupts happen at the time they are programmed, only it is
>their handling which may be delayed, most probably due to interrupts
>masking sections.
>
OK, I understand it now, thanks.

Robert