c-user: Document EDF SMP

Close #3056.

c-user/configuring_a_system.rst

@@ -3795,6 +3795,33 @@ DESCRIPTION:
 NOTES:
     None.
 
+.. COMMENT: === CONFIGURE_SCHEDULER_EDF_SMP ===
+
+.. _Use Earliest Deadline First SMP Scheduler:
+
+Use Earliest Deadline First Scheduler
+-------------------------------------
+.. index:: CONFIGURE_SCHEDULER_EDF_SMP
+
+CONSTANT:
+    ``CONFIGURE_SCHEDULER_EDF_SMP``
+
+DATA TYPE:
+    Boolean feature macro.
+
+RANGE:
+    Defined or undefined.
+
+DEFAULT VALUE:
+    This is not defined by default.
+
+DESCRIPTION:
+    If defined, then the Earliest Deadline First (EDF) SMP Scheduler is
+    selected as the default scheduler.
+
+NOTES:
+    None.
+
 .. COMMENT: === CONFIGURE_SCHEDULER_CBS ===
 
 .. _Use Constant Bandwidth Server Scheduler:

c-user/scheduling_concepts.rst

@@ -183,6 +183,13 @@ period, it has to be finished until the end of this period. The call of
 deadline. Moreover, the ``rtems_rate_monotonic_cancel`` and
 ``rtems_rate_monotonic_delete`` calls clear the deadlines assigned to the task.
 
+Earliest Deadline First SMP Scheduler
+-------------------------------------
+
+An EDF scheduler with SMP support.  The processors managed by this scheduler
+are allocated to the highest priority (earliest deadline) tasks which are ready
+to execute.
+
 Constant Bandwidth Server Scheduling (CBS)
 ------------------------------------------
 .. index:: constant bandwidth server scheduling