Re: [PATCH 10/12] scheduler: Simplify simple scheduler

Thu, 13 Jun 2013 11:47:38 -0700 

On 13/06/13 20:21, Sebastian Huber wrote:

On 13/06/13 18:06, Gedare Bloom wrote:

On Thu, Jun 13, 2013 at 12:01 PM, Gedare Bloom <[email protected]> wrote:

On Wed, Jun 12, 2013 at 11:29 AM, Sebastian Huber
<[email protected]> wrote:

Add and use _Scheduler_simple_Insert_as_first_order(),
_Scheduler_simple_Insert_as_last_order(),
_Scheduler_simple_Insert_as_first() and
_Scheduler_simple_Insert_as_last().
---
.../score/inline/rtems/score/schedulersimple.inl | 46 ++++++++++++++++++++ 
  .../score/src/schedulersimplereadyqueueenqueue.c   |   21 +--------
.../src/schedulersimplereadyqueueenqueuefirst.c | 26 +---------- 
  3 files changed, 50 insertions(+), 43 deletions(-)
diff --git a/cpukit/score/inline/rtems/score/schedulersimple.inl b/cpukit/score/inline/rtems/score/schedulersimple.inl 
index e67fc3c..1b58c85 100644
--- a/cpukit/score/inline/rtems/score/schedulersimple.inl
+++ b/cpukit/score/inline/rtems/score/schedulersimple.inl
@@ -48,6 +48,52 @@ RTEMS_INLINE_ROUTINE void _Scheduler_simple_Ready_queue_requeue( 
    _Scheduler_simple_Ready_queue_enqueue( the_thread );
  }

+RTEMS_INLINE_ROUTINE bool _Scheduler_simple_Insert_as_first_order(
+  const Chain_Node *to_insert,
+  const Chain_Node *next
+)
+{
+ const Thread_Control *thread_to_insert = (const Thread_Control *) to_insert; 
+  const Thread_Control *thread_next = (const Thread_Control *) next;
+
+ return thread_to_insert->current_priority <= thread_next->current_priority; 
+}
+
+RTEMS_INLINE_ROUTINE bool _Scheduler_simple_Insert_as_last_order(
+  const Chain_Node *to_insert,
+  const Chain_Node *next
+)
+{
+ const Thread_Control *thread_to_insert = (const Thread_Control *) to_insert; 
+  const Thread_Control *thread_next = (const Thread_Control *) next;
+
+ return thread_to_insert->current_priority < thread_next->current_priority; 
+}
+
+RTEMS_INLINE_ROUTINE void _Scheduler_simple_Insert_as_first(
+  Chain_Control *chain,
+  Thread_Control *to_insert
+)
+{
+  _Chain_Insert_ordered_unprotected(
+    chain,
+    &to_insert->Object.Node,
+    _Scheduler_simple_Insert_as_first_order
+  );
+}
+
+RTEMS_INLINE_ROUTINE void _Scheduler_simple_Insert_as_last(
+  Chain_Control *chain,
+  Thread_Control *to_insert
+)
+{
+  _Chain_Insert_ordered_unprotected(
+    chain,
+    &to_insert->Object.Node,
+    _Scheduler_simple_Insert_as_last_order
+  );
+}

For these functions _Scheduler_simple_Insert_as_first() and
_Scheduler_simple_Insert_as_last() the name means they break priority
ties by FIFO and LIFO semantics? Before I read the code, I thought it
meant break ties by inserting to the first or last position of ties,
which is the opposite. I would prefer to have
_Scheduler_simple_Insert_as_fifo()/lifo() instead for added clarity.


I guess saying fifo/lifo could be confusing also, since the insert is
not fifo/lifo, just how priority ties are broken. So maybe
_Scheduler_simple_Insert_priority_fifo()/lifo()?


Suppose we have 0 < 5_0 <= 5_1 < 10, then insert 5_2 as first will yield

0 < 5_2 <= 5_0 <= 5_1 < 10

and insert 5_2 as last will yield

0 < 5_0 <= 5_1 <= 5_2 < 10

I will use your suggestions.
Now I think that the LIFO/FIFO talks to much about a particular use case. What about 

_Scheduler_simple_Insert_as_first_of_priority_group()

?

--
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : [email protected]
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.

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