real time linux - which to use?

real time linux - which to use?

[Neel Mehta]

Hi. I am new to real time linux os. I need to set up one. I came
across two realtime linux os/kernels/patches, and there may be more. I
came across http://www.rtlinuxfree.com/ and https://www.rtai.org/.

Are there more such patches? Is anyone better? What do people use
normally? I need to set up realtime linux to get results from sensors
every periodic intervals. I want this to be hard realtime. Any help
will be greatly appreciated. Instructions or links for compilation
will also be very helpful.

Thanks and Regards,
Neel Mehta
Third year Undergraduate student,
Electrical Engineering,
IIT Bombay
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Re: real time linux - which to use?

[Armin Steinhoff]

Neel Mehta wrote:
> Hi. I am new to real time linux os. I need to set up one. I came
> across two realtime linux os/kernels/patches, and there may be more. I
> came across http://www.rtlinuxfree.com/ and https://www.rtai.org/.
>
> Are there more such patches? Is anyone better? 

The best approach is to use the real-time Linux version which doesn't 
have a name today.

It is the version PREEMPT_RT Real-Time-Linux  ...  I'm not sure  if this 
is the right name??
Or was it RT_PREEMPT Linux ?? Or was it RT-Preempt ??

However ... it's the Linux version which will be derived from the 
standard kernel by applying the PREEMPT_RT patch

--Armin

Re: real time linux - which to use?

[Pradyumna Sampath]

Hi Neel,

On Thu, Jun 10, 2010 at 2:57 PM, Neel Mehta <neelmehta89@gmail.com> wrote:
>
> Hi. I am new to real time linux os. I need to set up one. I came
> across two realtime linux os/kernels/patches, and there may be more. I
> came across http://www.rtlinuxfree.com/ and https://www.rtai.org/.

Real-time approaches to Linux are native real-time on Linux which is
what RT_PREEMPT tries to achieve. This fairly new compared to the
older approaches to provide real-time performance with Linux and that
is teh co-kernel approach. I have been using RT_PREEMPT for a few
years now and it has served me well.

> Are there more such patches? Is anyone better? What do people use
> normally? I need to set up realtime linux to get results from sensors
> every periodic intervals. I want this to be hard realtime. Any help
> will be greatly appreciated. Instructions or links for compilation
> will also be very helpful.

Check out http://rt.wiki.kernel.org .

regards
/prady

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http://www.prady.in
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Re: real time linux - which to use?

[Nicholas Mc Guire]

On Thu, 10 Jun 2010, Neel Mehta wrote:

> Hi. I am new to real time linux os. I need to set up one. I came
> across two realtime linux os/kernels/patches, and there may be more. I
> came across?http://www.rtlinuxfree.com/?and?https://www.rtai.org/.
>

regarding RTLinux/RTAI, RTLinux is dead so if one of those to then RTAI

Alternatives are the Xenomain and Xenomai-Solo and of course RT-Preempt
 
> Are there more such patches? Is anyone better? What do people use
> normally? I need to set up realtime linux to get results from sensors
> every periodic intervals. I want this to be hard realtime. Any help
> will be greatly appreciated. Instructions or links for compilation
> will also be very helpful.
>

a bit of background with respect to bandwidth needs, periods involved and
architecture would be helpfull to give you some hints. There is no 
"one-fits-all" solution around...

hofrat

Re: real time linux - which to use?

[Neel Mehta]

Thank you all for your help. I will provide a bit of background as to
what I wish to do.

I am working on an automatic railways project, and we have a lot of
sensors like GPS, laser, infrared, ultrasonic, cameras, etc. Each of
these works in an while loop, and tries to improve the quality of the
results. What I need is results at regular intervals. The time
interval depends on the speed of the train. So, I wish to develop my
application on realtime linux, so as to get the results at regular
intervals. I will be using TDL (Time Definition Language) for this
purpose. I would be generating software interrupts for machines doing
the processing of the sensors, and they in turn will return me the
result of the sensor, at that given moment of time.

I hope this helps to give you a picture of what I wish to do. Maybe
now you can suggest me the best alternative.

Thanks and Regards,
Neel Mehta
Third year Undergraduate student,
Electrical Engineering,
IIT Bombay


On Thu, Jun 10, 2010 at 3:16 PM, Nicholas Mc Guire <der.herr@hofr.at> wrote:
>
> On Thu, 10 Jun 2010, Neel Mehta wrote:
>
> > Hi. I am new to real time linux os. I need to set up one. I came
> > across two realtime linux os/kernels/patches, and there may be more. I
> > came across?http://www.rtlinuxfree.com/?and?https://www.rtai.org/.
> >
>
> regarding RTLinux/RTAI, RTLinux is dead so if one of those to then RTAI
>
> Alternatives are the Xenomain and Xenomai-Solo and of course RT-Preempt
>
> > Are there more such patches? Is anyone better? What do people use
> > normally? I need to set up realtime linux to get results from sensors
> > every periodic intervals. I want this to be hard realtime. Any help
> > will be greatly appreciated. Instructions or links for compilation
> > will also be very helpful.
> >
>
> a bit of background with respect to bandwidth needs, periods involved and
> architecture would be helpfull to give you some hints. There is no
> "one-fits-all" solution around...
>
> hofrat