Hi,
I'm sorry, I did not! Thanks for the suggestions. I'll go through its
calling functions, and the functions it calls.
On Sat, Jun 20, 2020 at 7:51 PM Gedare Bloom <ged...@rtems.org> wrote:
> On Sat, Jun 20, 2020 at 6:12 AM Richi Dubey <richidu...@gmail.com> wrote:
> >
> > Hi,
> >
> > I've been learning how SMP scheduler word in RTEMS and I came across the
> following function definition:
> >
> --------------------------------------------------------------------------------------------
> >
> > /**
> > * @brief Allocates the cpu for the scheduled thread.
> > *
> > * Attempts to prevent migrations but does not take into account
> affinity.
> > *
> > * @param context The scheduler context instance.
> > * @param scheduled The scheduled node that should be executed next.
> > * @param victim If the heir is this node's thread, no processor is
> allocated.
> > * @param[in, out] victim_cpu The cpu to allocate.
> > */
> >
> > static inline void _Scheduler_SMP_Allocate_processor_lazy(
> > Scheduler_Context *context,
> > Scheduler_Node *scheduled,
> > Scheduler_Node *victim,
> > Per_CPU_Control *victim_cpu
> > )
> > {
> > Thread_Control *scheduled_thread = _Scheduler_Node_get_user( scheduled
> );
> > Thread_Control *victim_thread = _Scheduler_Node_get_user( victim );
> > Per_CPU_Control *scheduled_cpu = _Thread_Get_CPU( scheduled_thread );
> > Per_CPU_Control *cpu_self = _Per_CPU_Get();
> > Thread_Control *heir;
> >
> > _Assert( _ISR_Get_level() != 0 );
> >
> > if ( _Thread_Is_executing_on_a_processor( scheduled_thread ) ) {
> > if ( _Scheduler_SMP_Is_processor_owned_by_us( context, scheduled_cpu
> ) ) {
> > heir = scheduled_cpu->heir;
> > _Thread_Dispatch_update_heir(
> > cpu_self,
> > scheduled_cpu,
> > scheduled_thread
> > );
> > } else {
> > /* We have to force a migration to our processor set */
> > heir = scheduled_thread;
> > }
> > } else {
> > heir = scheduled_thread;
> > }
> >
> > if ( heir != victim_thread ) {
> > _Thread_Set_CPU( heir, victim_cpu );
> > _Thread_Dispatch_update_heir( cpu_self, victim_cpu, heir );
> > }
> > }
> >
> >
> >
> --------------------------------------------------------------------------------
> > Can someone please help me understand what this function is trying to do
> and how exactly it is achieving that? I am finding it hard to understand
> the meaning and use of the terms like cpu_self (why do we need cpu_self ?
> Is it the CPU for scheduled or for victim?),
> _Thread_Is_executing_on_a_processor( scheduled_thread ): Why would we have
> the thread already executing when we need to allocate a processor to it?
> Why are we allocating a processor then?
> >
>
> Have you looked at how the function gets called/used? Or more
> importantly, when it gets called?
>
> you see cpu_self = Per_CPU_Get();
> Have you looked at that function to see what it does yet? Does it need
> better documentation/doxygen?
>
> > Thanks,
> > Richi.
> >
> > _______________________________________________
> > devel mailing list
> > devel@rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel
>
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