[LITMUS^RT] question about rtspin -- Sisu

[Björn Brandenburg]

On 17.04.2013, at 04:57, Sisu Xi <xisisu at gmail.com> wrote:

> I am trying to understand the rtspin program and have some question about it.
> 
> 1) Seems it will read execution time from a file. Is this the execution time for each individual job? 

Yes

> Is there any sample file for this? How should I format the file?

I don't have a sample file, but the format should be fairly simple. Chris Kenna implemented this; he might be able to tell you more about this.

Anyway, the file support is entirely optional, you don't have to use it (I usually don't).

> 
> 2) The budget enforcement, if configured as precise_enforcement, will force job to yield when it exceed wcet. 
> However, if I configure it as no_enforcement, the wcet parameter won't be used. cause the scheduling decision are made based on period/deadline, is this correct?

That depends on which scheduling plugin you are using. The scheduling policy has nothing to do with rtspin.

> 3) Is it possible to run multiple rtspin task at the same time? I see it records time using:
> 
> 	while (now + last_loop < start + exec_time) {
> 		loop_start = now;
> 		tmp += loop_once();
> 		now = cputime();
> 		last_loop = now - loop_start;
> 
> If multiple tasks are running, would't the time be incorrect?

No. Why would it?

- Björn