[PATCH] c-user: Add task priority glossary terms

[Gedare Bloom]

On Wed, May 12, 2021 at 8:50 AM Joel Sherrill <joel at rtems.org> wrote:
>
> Looks good.
>
> On Wed, May 12, 2021 at 8:07 AM Sebastian Huber <sebastian.huber at embedded-brains.de> wrote:
>>
>> ---
>>  c-user/glossary.rst | 41 ++++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 38 insertions(+), 3 deletions(-)
>>
>> diff --git a/c-user/glossary.rst b/c-user/glossary.rst
>> index b3527a7..5a06c10 100644
>> --- a/c-user/glossary.rst
>> +++ b/c-user/glossary.rst
>> @@ -194,6 +194,14 @@ Glossary
>>          This term is an acronym for Cathode Ray Tube.  Normally used in reference to
>>          the man-machine interface.
>>
>> +    current priority
>> +        The current priority of a :term:`task` is the :term:`task priority` with
>> +        respect to the :term:`home scheduler` of the task.  It is an aggregation of
>> +        the :term:`real priority` and temporary priority adjustments due to locking
>> +        protocols, the rate-monotonic period objects on some schedulers such as EDF,
>> +        and the :term:`POSIX` sporadic server.  The current priority is an
>> +        :term:`eligible priority`.
>> +
>>      deadline
>>          A fixed time limit by which a task must have completed a set of actions.
>>          Beyond this point, the results are of reduced value and may even be
>> @@ -246,6 +254,12 @@ Glossary
>>          This term is an acronym for
>>          `Executable and Linkable Format <https://en.wikipedia.org/wiki/Executable_and_Linkable_Format>`_.
>>
>> +    eligible priority
>> +        An eligible priority of a :term:`task` is the :term:`task priority` with
>> +        respect to the corresponding :term:`eligible scheduler` of the task.  An
>> +        eligible priority is either the :term:`current priority` and a
 "and" should be "or" ?

>> +        :term:`helping priority` of a task.
>> +
>>      eligible scheduler
>>          An eligible scheduler of a :term:`task` is a :term:`scheduler` which can be
>>          used by the task to allocate a processor for the task.
>> @@ -366,6 +380,11 @@ Glossary
>>          dispatch is marked as necessary, then the next thread dispatch will make
>>          the heir task the executing task.
>>
>> +    helping priority
>> +        A helping priority of a :term:`task` is the :term:`task priority` with
>> +        respect to the corresponding :term:`helping scheduler` of the task.  A
>> +        helping priority is an :term:`eligible priority`.
>> +
>>      helping scheduler
>>          A helping scheduler of a :term:`task` is a :term:`scheduler` which is a
>>          :term:`eligible scheduler` and which is not the :term:`home scheduler` of
>> @@ -632,9 +651,9 @@ Glossary
>>          another task.
>>
>>      priority
>> -        A mechanism used to represent the relative importance of an element in a
>> -        set of items.  RTEMS uses priority to determine which task should
>> -        execute.
>> +        The priority is a mechanism used to represent the relative importance of an
>> +        element in a set of items.  RTEMS uses :term:`task priorities <task priority>` to determine
>> +        which :term:`task` should execute.
>>
>>      priority boosting
>>          A simple approach to extend the priority inheritance protocol for
>> @@ -686,6 +705,14 @@ Glossary
>>          decided that other tasks are currently more important.  A task that is
>>          ready to execute and has a processor assigned is called scheduled.
>>
>> +    real priority
>> +        Each :term:`task` has exactly one real priority.  The real priority is
>> +        always with respect to the :term:`home scheduler` of a task.  It is defined
>> +        during task initialization.  It may be changed by directives such as
>> +        :c:func:`rtems_task_set_priority` and
>> +        :c:func:`rtems_task_set_scheduler`.  The real priority is the foundation
>> +        of the :term:`current priority`.
>> +
>>      real-time
>>          A term used to describe systems which are characterized by requiring
>>          deterministic response times to external stimuli.  The external stimuli
>> @@ -959,6 +986,14 @@ Glossary
>>          Task migration happens in case a task stops execution on one processor
>>          and resumes execution on another processor.
>>
>> +    task priority
>> +        A task priority of a :term:`task` determines its importance with respect to
>> +        other tasks.  The scheduler use task priorities to determine which
>> +        :term:`ready task` gets a processor allocated.  The
>> +        :term:`eligible priorities <eligible priority>` of a task define the position of the task in a
>> +        :term:`wait queue` which uses the priority discipline.  Each task has at
>> +        least the :term:`real priority`.
>> +
>>      task processor affinity
>>          The set of processors on which a task is allowed to execute.
>>
>> --
>> 2.26.2
>>
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