LinuxSA Mailing list archives

  From: hawjd001 <hawjd001@lux.levels.unisa.edu.au>
  To  : David Newall <davidn@rebel.net.au>
  Date: Wed, 31 Mar 1999 16:15:45 +0930 (GMT+9:30)

Re: Linux in real time (was More Meeting Information)

hey guys, if you are intersted in real-time linux applications, you should check out RT-Linux.

it has hard time-scheduling, , and there is a lot of work going on to get the accuracy of the task
switching higher.

i have used RT-Linux, and found that it is quite easy to progrm.

its donr by programming a kernel module.

What actually happnes though is the "normal" linux kernel runs as the lowest priority real-tim
eprocess under another kernel. the real-time kernel is where your home built module is inserted.

the real-time kernel suspends interupts untill the current task is over.


there is heaps of stuff about it here http://luz.cs.nmt.edu/~rtlinux/


last year my project group used rt-linux in a real time system controlling an electronic wheelchair
and an A2D board.

and if my hard drive hadn't crashed I could have pointed you to another web site with more info:(
> 
> On Wed, 31 Mar 1999, Daryl Tester wrote:
> > Linux (and possibly BSD) has real time extensions that enable
> > you to adjust the scheduling policy of a process.  man 2
> > sched_setscheduler for a plethora of information ...
> 
> It's not really real time.  It's really a higher-priority scheduling
> class: "real time" processes are run before other classes of process;
> so if a "real time" process wants to be a hog, nothing else runs.
> This is something I first saw in Unix SVR4 (it has three classes:
> Unix, Real Time and Kernel.)  The important consideration is that
> these processes are not real-time, for example there is no guarantee
> that a process will run within a specified time frame, which is the
> fundamental guarantee provided by a real real time operating system.
> 
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> 



MrJ					Computer Systems Engineering
hawjd001@lux.levels.unisa.edu.au	Unisa, Levels Campus 


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