[PATCH] Update RMS documentation for overrun handling

[Gedare Bloom]

I was unable to compile rtems-docs (cleanly), so I have not committed
this patch yet. If someone else who can compile docs can build with
this patch, please commit. I need to debug my baseline build still...

On Wed, Dec 21, 2016 at 11:44 AM, Kuan-Hsun Chen <c0066c at gmail.com> wrote:
> ---
>  c-user/rate_monotonic_manager.rst | 30 +++++++++++++++++-------------
>  1 file changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/c-user/rate_monotonic_manager.rst b/c-user/rate_monotonic_manager.rst
> index 8ad74e5..9ba22a5 100644
> --- a/c-user/rate_monotonic_manager.rst
> +++ b/c-user/rate_monotonic_manager.rst
> @@ -132,7 +132,7 @@ milliseconds every 100 (10 percent of the CPU).  As a general rule of thumb,
>  the higher frequency at which a task executes, the more important it is to
>  optimize that task.
>
> -Rate Monotonic Manager Definitions
> +Periodicity Definitions
>  ----------------------------------
>  .. index:: periodic task, definition
>
> @@ -170,7 +170,7 @@ Rate Monotonic Scheduling Algorithm
>  .. index:: RMS Algorithm, definition
>
>  The Rate Monotonic Scheduling Algorithm (RMS) is important to real-time systems
> -designers because it allows one to guarantee that a set of tasks is
> +designers because it allows one to sufficiently guarantee that a set of tasks is
>  schedulable.  A set of tasks is said to be schedulable if all of the tasks can
>  meet their deadlines.  RMS provides a set of rules which can be used to perform
>  a guaranteed schedulability analysis for a task set.  This analysis determines
> @@ -179,11 +179,11 @@ the predictability of the system's behavior.  It has been proven that:
>
>  .. sidebar:: *RMS*
>
> -  RMS is an optimal static priority algorithm for scheduling independent,
> +  RMS is an optimal fixed-priority algorithm for scheduling independent,
>    preemptible, periodic tasks on a single processor.
>
>  RMS is optimal in the sense that if a set of tasks can be scheduled by any
> -static priority algorithm, then RMS will be able to schedule that task set.
> +fixed-priority algorithm, then RMS will be able to schedule that task set.
>  RMS bases it schedulability analysis on the processor utilization level below
>  which all deadlines can be met.
>
> @@ -230,7 +230,7 @@ Schedulability Analysis
>
>  .. index:: RMS schedulability analysis
>
> -RMS allows application designers to ensure that tasks can meet all deadlines,
> +RMS allows application designers to ensure that tasks can meet all deadlines under fixed-priority assignment,
>  even under transient overload, without knowing exactly when any given task will
>  execute by applying proven schedulability analysis rules.
>
> @@ -468,9 +468,10 @@ monotonic period results in one of the following scenarios:
>    immediately.
>
>  - If the rate monotonic period has expired before the task invokes the
> -  ``rtems_rate_monotonic_period`` directive, the period will be initiated with
> -  a length of period ticks and the calling task returns immediately with a
> -  timeout error status.
> +  ``rtems_rate_monotonic_period`` directive, the postponed job will be released
> +  until there is no more postponed jobs. The calling task returns immediately
> +  with a timeout error status. In the watchdog routine, the period will still
> +  be updated periodically and track the number of the postponed periods.
>
>  Obtaining the Status of a Period
>  --------------------------------
> @@ -560,8 +561,8 @@ Subsequent invocations of the ``rtems_rate_monotonic_period`` directive will
>  result in the task blocking for the remainder of the 100 tick period.  If, for
>  any reason, the body of the loop takes more than 100 ticks to execute, the
>  ``rtems_rate_monotonic_period`` directive will return the ``RTEMS_TIMEOUT``
> -status.  If the above task misses its deadline, it will delete the rate
> -monotonic period and itself.
> +status and the postponed job will be released.  If the above task misses
> +its deadline, it will delete the rate monotonic period and itself.
>
>  Task with Multiple Periods
>  --------------------------
> @@ -629,8 +630,8 @@ will not block.
>
>  If, for any reason, the task misses any deadline, the
>  ``rtems_rate_monotonic_period`` directive will return the ``RTEMS_TIMEOUT``
> -directive status.  If the above task misses its deadline, it will delete the
> -rate monotonic periods and itself.
> +directive status and the postponed job will be released. If the above task misses
> +its deadline, it will delete the rate monotonic periods and itself.
>
>  Directives
>  ==========
> @@ -839,7 +840,10 @@ DESCRIPTION:
>      period ticks.  If id is running, then the calling task will block for the
>      remainder of the period before reinitiating the period with the specified
>      period.  If id was not running (either expired or never initiated), the
> -    period is immediately initiated and the directive returns immediately.
> +    period is immediately initiated and the directive returns immediately.
> +       If id has expired its period, the postponed job will be released immediately
> +       and the following calls of this directive will release postponed
> +       jobs until there is no more deadline miss.
>
>      If invoked with a period of ``RTEMS_PERIOD_STATUS`` ticks, the current
>      state of id will be returned.  The directive status indicates the current
> --
> 1.9.1
>
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