Re: Questions on developing applications...

[Klaas van Gend <klaas.van.gend@mvista.com>]

Brian Ford wrote:
> Hi Everyone,
> 
> I'm new to real time linux programming, apologies if these questions are 
> very simple.
> 
> I've recently setup a real time Linux kernel using patch-2.6.24.7-rt26  
> and got the simple "Hello World" program working. However, I'm unable
> to find any guides on how to write more complex software. 
> 
> Can you tell me how to do real time inter process message passing in linux?
> I'm familiar with shared memory and pipes -- is it ok to use these in 
> a real time context?
> 
> Also, I've read that printf may not provide real time performance. 
> (http://rt.wiki.kernel.org/index.php/HOWTO:_Build_an_RT-application)
> If I use printf/printk to a X UI terminal, will the output be deterministic (take a fixed time)?
> 
> I'm also interested in building a cyclic executive scheduler to control individual process. At
> the moment I'm guessing the only way to do this would be to modify the kernel scheduler. 
> Is it possible to do this at the application/process level?

It depends. Do you know about SCHED_FIFO and SCHED_RR ?
It sounds like that may already suit your needs.

If you're not familiar with those, please read up on this - e.g. in
Chapter 4 of Robert Love's book:    http://www.amazon.co.uk/dp/0672327201


-- 
Best regards,

Klaas van Gend

Senior Solutions & Services Architect
MontaVista Software
Phone: (408) 572 7962 (Santa Clara Office)
Phone: +31 40 2801386 (for European calls)