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, 4 insertions, 2 deletions

diff --git a/cpukit/score/src/schedulersimpleunblock.c b/cpukit/score/src/schedulersimpleunblock.c
index 5540e20e87..2f5c8636f5 100644
--- a/cpukit/score/src/schedulersimpleunblock.c
+++ b/cpukit/score/src/schedulersimpleunblock.c
@@ -28,13 +28,15 @@ void _Scheduler_simple_Unblock(
 )
 {
   Scheduler_simple_Context *context;
-  Priority_Control          priority;
+  unsigned int              priority;
+  unsigned int              insert_priority;
 
   (void) node;
 
   context = _Scheduler_simple_Get_context( scheduler );
-  _Scheduler_simple_Insert_priority_fifo( &context->Ready, the_thread );
   priority = _Thread_Get_priority( the_thread );
+  insert_priority = SCHEDULER_PRIORITY_APPEND( priority );
+  _Scheduler_simple_Insert( &context->Ready, the_thread, insert_priority );
 
   /*
    *  If the thread that was unblocked is more important than the heir,