[RTEMS Project] #3700: Add rtems_rate_monotonic_deadline()

[RTEMS trac]

#3700: Add rtems_rate_monotonic_deadline()
------------------------------+-----------------------------
  Reporter:  Sebastian Huber  |      Owner:  Sebastian Huber
      Type:  enhancement      |     Status:  assigned
  Priority:  normal           |  Milestone:  5.1
 Component:  rtems            |    Version:  5
  Severity:  normal           |   Keywords:
Blocked By:                   |   Blocking:
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 Depending on the scheduler selection, the rtems_rate_monotonic_period()
 behaves differently. In case the EDF scheduler is configured, then tasks
 using a rate-monotonic object have a higher priority (based on deadline)
 than the fixed priority background tasks. This is quite bad for
 applications which want to use the periods with a fixed priority just to
 get statistics and a deadline miss detection. The default SMP scheduler
 provides EDF functionality, so this is an issue while porting applications
 to SMP systems. To give applications more control, add a new function:
 {{{
 /**
  * @brief Starts a deadline and period.
  *
  * This routine starts a deadline and period.  In case Earliest Deadline
 First
  * (EDF) scheduling is available, then the priority of the executing task
 is
  * adjusted according to the specified deadline.  The next activation of
 the
  * executing task is specified by the period parameter.
  *
  * @param id The rate monotonic object identifier.
  * @param deadline The deadline in ticks.  Must be positive.
  * @param period The period in ticks.  Must be greater than or equal to
 the deadline.
  *
  * @retval RTEMS_SUCCESSFUL Successful operation.
  * @retval RTEMS_INVALID_ID No period objects exists for the specified
 object
  *   identifier.
  * @retval RTEMS_NOT_OWNER_OF_RESOURCE The period object belongs to
 another task.
  * @retval RTEMS_INVALID_NUMBER The deadline is zero or the period is less
 than the deadline.
  * @retval RTEMS_TIMEOUT The previous deadline was missed.
  */
 rtems_status_code rtems_rate_monotonic_deadline(
   rtems_id       id,
   rtems_interval deadline,
   rtems_interval period
 );
 }}}
 The new function uses two timing parameters to allow constrained deadlines
 and not only implicit deadlines.

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Ticket URL: <http://devel.rtems.org/ticket/3700>
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