On 02/15/2015 11:52 PM, Marius Alksnys wrote:
> On 02/16/2015 05:47 AM, Sebastian Kuzminsky wrote:
>> On 02/15/2015 07:32 AM, Marius Alksnys wrote:
>>> At http://wiki.linuxcnc.org/cgi-bin/wiki.pl?UpdatingTo2.7
>>>
>>> apt source lines for two different Debian Wheezy kernels and uses are
>>> the same. Shouldn't it be 2.7-rtpreempt ?
>>
>> Nope, the wiki page is correct.  Both the vanilla kernel and the
>> rt-preempt kernel use the "uspace" flavor of linuxcnc.
>>
>> The uspace flavor runs entirely in userspace, which is where it gets its
>> name.
>>
>> If you run the uspace flavor of linuxcnc on an rt-preempt kernel, you
>> get reasonable realtime performance.  In userspace!  Awesome!
> 
> I am not sure how to understand the kernel version. uname -a results:
> 3.4-9-rtai-686-pae #1 SMP PREEMPT Debian 3.4.55-4linuxcnc i686 GNU/Linux
> 
> You can look at the latency test histogram results I got, look at "base 
> 2.7-uspace" near the end:
> http://robotech.lt/?p=21

Your machine is using the RTAI kernel, as indicated by the "rtai" in the
kernel version string.

This means you should expect good latency when running the rtai flavor
of linuxcnc, and bad latency when running the uspace flavor.  Which is
what we see in your latency plots.


>> http://linuxcnc.org/docs/2.7/html/getting-started
> 
> New documentation and image - this is great!

:-)


-- 
Sebastian Kuzminsky

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