About locks and concurrency rules for SMP systems

[Richi Dubey]

Got it. Thank you for the clarification.

On Fri, Mar 26, 2021 at 8:32 PM Gedare Bloom <gedare at rtems.org> wrote:

> On Thu, Mar 25, 2021 at 11:30 PM Richi Dubey <richidubey at gmail.com> wrote:
> >
> > Thanks for your quick response!
> >
> >> Each scheduler has its own lock. There are a couple of more locks
> involved.
> >
> > I understand.
> >
> > I backtracked a little and found that we have:
> > _Thread_State_acquire_critical( the_thread, lock_context );
> >
> > to lock access to thread-specific variables.
> >
> > _Scheduler_Acquire_critical( scheduler, &lock_context
> >
> > to lock access to the current scheduler-specific data structures.
> >
> > What other locks do we have related to schedulers?
> >
>
> By definition, all locks relate to scheduling. The other major one
> though would be _Thread_Dispatch_disable_critical and relatives like
> _Thread_queue_Dispatch_disable, if you think of dispatching as part of
> scheduling. However, the two operations are a little bit different.
> Scheduling is selecting the next thread(s) to run, while dispatching
> is actually making them run.
>
>
> > On Wed, Mar 24, 2021 at 1:03 PM Sebastian Huber <
> sebastian.huber at embedded-brains.de> wrote:
> >>
> >> On 24/03/2021 08:07, Richi Dubey wrote:
> >>
> >> > How does RTEMS handle cases where two different cores access
> >> > scheduler-related functions at the same time?
> >> Each scheduler has its own lock. There are a couple of more locks
> involved.
> >> > For ex., Can they access (or modify) the Scheduler_strong_APA_Context
> >> > <
> https://git.rtems.org/rtems/tree/cpukit/include/rtems/score/schedulerstrongapa.h#n61
> >
> >> > at the same time?
> >> No, unless we have a bug.
> >>
> >> --
> >> embedded brains GmbH
> >> Herr Sebastian HUBER
> >> Dornierstr. 4
> >> 82178 Puchheim
> >> Germany
> >> email: sebastian.huber at embedded-brains.de
> >> phone: +49-89-18 94 741 - 16
> >> fax:   +49-89-18 94 741 - 08
> >>
> >> Registergericht: Amtsgericht München
> >> Registernummer: HRB 157899
> >> Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler
> >> Unsere Datenschutzerklärung finden Sie hier:
> >> https://embedded-brains.de/datenschutzerklaerung/
> >>
> > _______________________________________________
> > devel mailing list
> > devel at rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rtems.org/pipermail/devel/attachments/20210329/b7048c5b/attachment.html>