score: Optimize scheduler priority updates

Thread priority changes may append or prepend the thread to its priority
group on the scheduler ready queue.  Previously, a separate priority
value and a prepend-it flag in the scheduler node were used to propagate
a priority change to the scheduler.

Now, use an append-it bit in the priority control and reduce the plain
priority value to 63 bits.

This change leads to a significant code size reduction (about 25%) of
the SMP schedulers.  The negligible increase of the standard priority
scheduler is due to some additional shift operations
(SCHEDULER_PRIORITY_MAP() and SCHEDULER_PRIORITY_UNMAP()).

Before:

   text filename
    136 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleblock.o
    464 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimplechangepriority.o
     24 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimple.o
    108 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleschedule.o
    292 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleunblock.o
    264 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleyield.o

   text filename
    280 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityblock.o
    488 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerprioritychangepriority.o
    200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriority.o
    164 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityschedule.o
    328 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityunblock.o
    200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityyield.o

   text filename
  24112 arm-rtems5/c/imx7/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  37204 sparc-rtems5/c/gr740/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  42236 powerpc-rtems5/c/qoriq_e6500_32/cpukit/score/src/libscore_a-scheduleredfsmp.o

After:

   text filename
    136 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleblock.o
    272 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimplechangepriority.o
     24 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimple.o
    108 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleschedule.o
    292 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleunblock.o
    264 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleyield.o

   text filename
    280 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityblock.o
    488 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerprioritychangepriority.o
    208 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriority.o
    164 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityschedule.o
    332 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityunblock.o
    200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityyield.o

   text filename
  18860 arm-rtems5/c/imx7/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  28520 sparc-rtems5/c/gr740/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  32664 powerpc-rtems5/c/qoriq_e6500_32/cpukit/score/src/libscore_a-scheduleredfsmp.o

1 files changed, 35 insertions, 40 deletions

diff --git a/cpukit/score/include/rtems/score/schedulerprioritysmpimpl.h b/cpukit/score/include/rtems/score/schedulerprioritysmpimpl.h
index 073a7ade06..17d6e552f3 100644
--- a/cpukit/score/include/rtems/score/schedulerprioritysmpimpl.h
+++ b/cpukit/score/include/rtems/score/schedulerprioritysmpimpl.h
@@ -7,7 +7,7 @@
  */
 
 /*
- * Copyright (c) 2013-2014 embedded brains GmbH.  All rights reserved.
+ * Copyright (c) 2013, 2017 embedded brains GmbH.  All rights reserved.
  *
  *  embedded brains GmbH
  *  Dornierstr. 4
@@ -90,7 +90,7 @@ static inline void _Scheduler_priority_SMP_Move_from_ready_to_scheduled(
 {
   Scheduler_priority_SMP_Context *self;
   Scheduler_priority_SMP_Node    *node;
-  Priority_Control                priority;
+  Priority_Control                insert_priority;
 
   self = _Scheduler_priority_SMP_Get_self( context );
   node = _Scheduler_priority_SMP_Node_downcast( ready_to_scheduled );
@@ -100,47 +100,41 @@ static inline void _Scheduler_priority_SMP_Move_from_ready_to_scheduled(
     &node->Ready_queue,
     &self->Bit_map
   );
-  priority = node->Base.priority;
+  insert_priority = _Scheduler_SMP_Node_priority( &node->Base.Base );
+  insert_priority = SCHEDULER_PRIORITY_APPEND( insert_priority );
   _Chain_Insert_ordered_unprotected(
     &self->Base.Scheduled,
     &node->Base.Base.Node.Chain,
-    &priority,
-    _Scheduler_SMP_Insert_priority_fifo_order
+    &insert_priority,
+    _Scheduler_SMP_Priority_less_equal
   );
 }
 
-static inline void _Scheduler_priority_SMP_Insert_ready_lifo(
+static inline void _Scheduler_priority_SMP_Insert_ready(
   Scheduler_Context *context,
-  Scheduler_Node    *thread
-)
-{
-  Scheduler_priority_SMP_Context *self =
-    _Scheduler_priority_SMP_Get_self( context );
-  Scheduler_priority_SMP_Node *node =
-    _Scheduler_priority_SMP_Node_downcast( thread );
-
-  _Scheduler_priority_Ready_queue_enqueue(
-    &node->Base.Base.Node.Chain,
-    &node->Ready_queue,
-    &self->Bit_map
-  );
-}
-
-static inline void _Scheduler_priority_SMP_Insert_ready_fifo(
-  Scheduler_Context *context,
-  Scheduler_Node    *thread
+  Scheduler_Node    *node_base,
+  Priority_Control   insert_priority
 )
 {
-  Scheduler_priority_SMP_Context *self =
-    _Scheduler_priority_SMP_Get_self( context );
-  Scheduler_priority_SMP_Node *node =
-    _Scheduler_priority_SMP_Node_downcast( thread );
+  Scheduler_priority_SMP_Context *self;
+  Scheduler_priority_SMP_Node    *node;
 
-  _Scheduler_priority_Ready_queue_enqueue_first(
-    &node->Base.Base.Node.Chain,
-    &node->Ready_queue,
-    &self->Bit_map
-  );
+  self = _Scheduler_priority_SMP_Get_self( context );
+  node = _Scheduler_priority_SMP_Node_downcast( node_base );
+
+  if ( SCHEDULER_PRIORITY_IS_APPEND( insert_priority ) ) {
+    _Scheduler_priority_Ready_queue_enqueue(
+      &node->Base.Base.Node.Chain,
+      &node->Ready_queue,
+      &self->Bit_map
+    );
+  } else {
+    _Scheduler_priority_Ready_queue_enqueue_first(
+      &node->Base.Base.Node.Chain,
+      &node->Ready_queue,
+      &self->Bit_map
+    );
+  }
 }
 
 static inline void _Scheduler_priority_SMP_Extract_from_ready(
@@ -162,19 +156,20 @@ static inline void _Scheduler_priority_SMP_Extract_from_ready(
 
 static inline void _Scheduler_priority_SMP_Do_update(
   Scheduler_Context *context,
-  Scheduler_Node *node_to_update,
-  Priority_Control new_priority
+  Scheduler_Node    *node_to_update,
+  Priority_Control   new_priority
 )
 {
-  Scheduler_priority_SMP_Context *self =
-    _Scheduler_priority_SMP_Get_self( context );
-  Scheduler_priority_SMP_Node *node =
-    _Scheduler_priority_SMP_Node_downcast( node_to_update );
+  Scheduler_priority_SMP_Context *self;
+  Scheduler_priority_SMP_Node    *node;
+
+  self = _Scheduler_priority_SMP_Get_self( context );
+  node = _Scheduler_priority_SMP_Node_downcast( node_to_update );
 
   _Scheduler_SMP_Node_update_priority( &node->Base, new_priority );
   _Scheduler_priority_Ready_queue_update(
     &node->Ready_queue,
-    new_priority,
+    SCHEDULER_PRIORITY_UNMAP( new_priority ),
     &self->Bit_map,
     &self->Ready[ 0 ]
   );