score: Rework EDF scheduler

Use inline red-black tree insert.  Do not use shifting priorities since
this is not supported by the thread queues.  Due to the 32-bit
Priority_Control this currently limits the uptime to 49days with a 1ms
clock tick.

Update #2173.

1 files changed, 19 insertions, 11 deletions

diff --git a/cpukit/score/src/scheduleredfchangepriority.c b/cpukit/score/src/scheduleredfchangepriority.c
index 6efbf87ad3..a0f5ec7061 100644
--- a/cpukit/score/src/scheduleredfchangepriority.c
+++ b/cpukit/score/src/scheduleredfchangepriority.c
@@ -43,17 +43,25 @@ Scheduler_Void_or_thread _Scheduler_EDF_Change_priority(
   bool                     prepend_it
 )
 {
-  Scheduler_EDF_Context *context =
-    _Scheduler_EDF_Get_context( scheduler );
-  Scheduler_EDF_Node *node = _Scheduler_EDF_Thread_get_node( the_thread );
-
-  _RBTree_Extract( &context->Ready, &node->Node );
-  _RBTree_Insert(
-    &context->Ready,
-    &node->Node,
-    _Scheduler_EDF_Compare,
-    false
-  );
+  Scheduler_EDF_Context *context;
+  Scheduler_EDF_Node    *node;
+
+  context = _Scheduler_EDF_Get_context( scheduler );
+  node = _Scheduler_EDF_Thread_get_node( the_thread );
+
+  if ( ( new_priority & SCHEDULER_EDF_PRIO_MSB ) != 0 ) {
+    node->background_priority = new_priority;
+  }
+
+  node->current_priority = new_priority;
+
+  _Scheduler_EDF_Extract( context, node );
+
+  if ( prepend_it ) {
+    _Scheduler_EDF_Enqueue_first( context, node, new_priority );
+  } else {
+    _Scheduler_EDF_Enqueue( context, node, new_priority );
+  }
 
   _Scheduler_EDF_Schedule_body( scheduler, the_thread, false );