[LITMUS^RT] Question about Litmus-RT yields CPU when finished with a task

[Yu-An(Victor) Chen]

Hi Meng,

Thank you very much for your reply!

Victor

On Sat, May 28, 2016 at 5:02 PM, Meng Xu <xumengpanda at gmail.com> wrote:

> Hi Victor,
>
> On Sat, May 28, 2016 at 5:36 PM, Yu-An(Victor) Chen <chen116 at usc.edu>
> wrote:
> > Hi,
> >
> > My question is how does litmus-RT kernel give up CPUs when running a
> task?
> > Given a period and execution time of a task, will litmus-RT kernel yields
> > the CPU as soon as a task is finished? or will give up the CPU only when
> the
> > task's period is reached?
>
> IIRC, when a task finishes its execution (or budget) or get blocked,
> the task will yield CPU. The scheduler will schedule the next ready
> task. You can have a look at the schedule and _finish function in
> litmus/sched_gsn_edf.c. It will deschedule a task if it finishes its
> execution.
>
> >
> > For example, lets say I have two tasks with same utilization but one has
> > longer period. And I run this two tasks on separate machine with same
> > duration. Can I safely assume that the task with shorter period will have
> > the litmus-RT yielding CPUs more frequently?
>
> The short-period task has more jobs. So as long as its utilization is
> less than 1, it should be, IMHO.
>
> >
> > Please let me know if there is any reference or paper I can read on
> > regarding litmus-RT yielding CPUs. Thank you very much!
>
> I guess the code is the best reference. :-)
>
>
> Best Regards,
>
> Meng
> -----------
> Meng Xu
> PhD Student in Computer and Information Science
> University of Pennsylvania
>
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