Re: PREEMPT_RT patch vs RTAI/Xenomai

[Armin Steinhoff <armin@steinhoff.de>]

Nivedita Singhvi wrote:
> Armin Steinhoff wrote:
>
>>> If tuned properly, PREEMPT_RT can easily handle 1ms requirements. On a
>>> standard x86 CPU (we support others than x86) our goal is never to be
>>>   
>>
>> I did a test with user space based CAN driver.
>> Already the standard distribution of SUSE 11.2 (non RT) was able to 
>> handle 1000 frames per seconds sent by a QNX6 machine !!
>
> If your requirements are "never to exceed" a certain latency,
> I highly recommend you run tests for long-durations, rather
> than a short period. A 10-min or even a 1 hour run will not
> give you a full idea as a 24-72 hour run will.

The test was running for more than 12 hours. That's the typical test 
before the software will be released.

>
>> The PREEMPT_RT version of SUSE 11.2 is much, much faster :-)
>>> over 100us in reaction time.
>>>   
>>
>> The latency test of PREEMPT_RT shows a latency of ~10us for a 
>> dual-core box at 1.8GHz.
>
> Are you using cyclictest? And how long did you run it for?

Several hours ...

--Armin

PS: my initial post has been posted again because of internet problems, 
sorry.