OK - but see here:
https://nuttx.apache.org/docs/latest/reference/user/02_task_scheduling.html
Hardly a "default" if you have to read the help of Kconfig to see what's
going on?
I know the documentation is, um, lacking...so if it can be improved here
let's do it!
On 26/11/2025 18:12, Alan C. Assis wrote:
There is not a checkbox to ROUND ROBIN in the menuconfig:
image.png
Only for Sporadic scheduling. The the <Help> for the RR timeslice
explains it:
│ The round robin timeslice will be set this number of milliseconds;
│
│ Round robin scheduling (SCHED_RR) is enabled by setting this
│
│ interval to a positive, non-zero value.
On Wed, Nov 26, 2025 at 3:07 PM Matteo Golin <[email protected]>
wrote:
I suppose I would agree, that does seem misleading if the default
is RR.
Does the RR scheduling on NuttX have priority-based
preemption/priority
inversion avoidance mechanisms? Maybe that could be the reasoning for
the wording.
On Wed, Nov 26, 2025 at 1:00 PM Tim Hardisty <[email protected]>
wrote:
> That's what I inferred (yet to try it) - so is the documentation
> misleading since the default CONFIG_RR_INTERVAL=200 forces RR
scheduling
> rather than the stated "strict priority scheduling"?
>
> On 26/11/2025 17:54, Alan C. Assis wrote:
> > CONFIG_RR_INTERVAL=0
> >
> > On Wed, Nov 26, 2025 at 2:22 PM Tim Hardisty
<[email protected]>
> > wrote:
> >
> >> Apologies if this isn't really a NuttX question...
> >>
> >> Documentation says "By default, NuttX performs strict priority
> scheduling".
> >>
> >> Default CONFIG_RR_INTERVAL is 200ms.
> >>
> >> I have multiple threads, but have not set any scheduling
parameters, but
> >> it seems threads are being scheduled every 200ms rather on a
priority
> >> basis.
> >>
> >> What *should* I be doing, please, to get all my threads
scheduled by
> >> priority?
> >>
> >> Thanks,
> >>
> >> TimH
> >>
> >> PS - yes I have thrown myself in the deep end without a life
jacket with
> >> my project. And I'm no doubt up ****-creek without a paddle.
But I am
> >> always learning!
> >>
>
