Thank you for the clarification. On Wed, Aug 5, 2020 at 1:00 PM Sebastian Huber < sebastian.hu...@embedded-brains.de> wrote:
> On 04/08/2020 17:57, Gedare Bloom wrote: > > On Tue, Aug 4, 2020 at 8:14 AM Richi Dubey<richidu...@gmail.com> wrote: > >> Hi, > >> > >> I have a quick doubt about the logic in the else part of the > _Scheduler_SMP_Schedule_highest_ready function. > >> > > I'll give my understanding. Only Sebastian really understands this > stuff;) > > > >> We get the action == SCHEDULER_TRY_TO_SCHEDULE_DO_BLOCK if the node > returned by get_highest_ready is already SCHEDULED and has a pinning level > of 1 (or <=1). This means that the highest ready eligible node is already > scheduled and pinned to a processor. > >> > > This means that the highest ready node cannot be scheduled right now, > > for some reason. It is the thread that is already scheduled, or the > > node is busy helping. > > > >> Why do we then change its state to BLOCKED and remove it from the chain > of ready nodes? > >> > > If the thread that owns the node can't be scheduled right now (e.g., > > it is already scheduled on a different node), then the node should be > > blocked so we can maybe pick a different node to schedule. > > Yes. I tried to improve the documentation a bit: > > https://lists.rtems.org/pipermail/devel/2020-August/061144.html > > What can be a bit confusing is that we have a scheduled state for > threads and for scheduler nodes: > > /** > * @brief The thread state with respect to the scheduler. > */ > typedef enum { > /** > * @brief This thread is blocked with respect to the scheduler. > * > * This thread uses no scheduler nodes. > */ > THREAD_SCHEDULER_BLOCKED, > > /** > * @brief This thread is scheduled with respect to the scheduler. > * > * This thread executes using one of its scheduler nodes. This could > be its > * own scheduler node or in case it owns resources taking part in the > * scheduler helping protocol a scheduler node of another thread. > */ > THREAD_SCHEDULER_SCHEDULED, > > /** > * @brief This thread is ready with respect to the scheduler. > * > * None of the scheduler nodes of this thread is scheduled. > */ > THREAD_SCHEDULER_READY > } Thread_Scheduler_state; > > > /** > * @brief SMP scheduler node states. > */ > typedef enum { > /** > * @brief This scheduler node is blocked. > * > * A scheduler node is blocked if the corresponding thread is not ready. > */ > SCHEDULER_SMP_NODE_BLOCKED, > > /** > * @brief The scheduler node is scheduled. > * > * A scheduler node is scheduled if the corresponding thread is ready > and the > * scheduler allocated a processor for it. A scheduled node is > assigned to > * exactly one processor. The count of scheduled nodes in this > scheduler > * instance equals the processor count owned by the scheduler instance. > */ > SCHEDULER_SMP_NODE_SCHEDULED, > > /** > * @brief This scheduler node is ready. > * > * A scheduler node is ready if the corresponding thread is ready and > the > * scheduler did not allocate a processor for it. > */ > SCHEDULER_SMP_NODE_READY > } Scheduler_SMP_Node_state; > -- > Sebastian Huber, embedded brains GmbH > > Address : Dornierstr. 4, D-82178 Puchheim, Germany > Phone : +49 89 189 47 41-16 > Fax : +49 89 189 47 41-09 > E-Mail : sebastian.hu...@embedded-brains.de > PGP : Public key available on request. > > Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG. >
_______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
