[PATCH 10/12] scheduler: Simplify simple scheduler

[Gedare Bloom]

On Thu, Jun 13, 2013 at 2:21 PM, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
> On 13/06/13 18:06, Gedare Bloom wrote:
>>
>> On Thu, Jun 13, 2013 at 12:01 PM, Gedare Bloom <gedare at rtems.org> wrote:
>>>
>>> On Wed, Jun 12, 2013 at 11:29 AM, Sebastian Huber
>>> <sebastian.huber at embedded-brains.de> 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.
>
OK. So "insert as first" implements a LIFO tie-break, and "insert as
last" implements FIFO

> --
> 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  : sebastian.huber at embedded-brains.de
> PGP     : Public key available on request.
>
> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>