source: rtems/cpukit/score/src/scheduleredfunblock.c @ 25f5730f

4.11
Last change on this file since 25f5730f was f39f667a, checked in by Sebastian Huber <sebastian.huber@…>, on May 14, 2014 at 11:50:48 AM

score: Simplify _Thread_Change_priority()

The function to change a thread priority was too complex. Simplify it
with a new scheduler operation. This increases the average case
performance due to the simplified logic. The interrupt disabled
critical section is a bit prolonged since now the extract, update and
enqueue steps are executed atomically. This should however not impact
the worst-case interrupt latency since at least for the Deterministic
Priority Scheduler this sequence can be carried out with a wee bit of
instructions and no loops.

Add _Scheduler_Change_priority() to replace the sequence of

  • _Thread_Set_transient(),
  • _Scheduler_Extract(),
  • _Scheduler_Enqueue(), and
  • _Scheduler_Enqueue_first().

Delete STATES_TRANSIENT, _States_Is_transient() and
_Thread_Set_transient() since this state is now superfluous.

With this change it is possible to get rid of the
SCHEDULER_SMP_NODE_IN_THE_AIR state. This considerably simplifies the
implementation of the new SMP locking protocols.

  • Property mode set to 100644
File size: 1.4 KB
Line 
1/**
2 * @file
3 *
4 * @brief Scheduler EDF Unblock
5 * @ingroup ScoreScheduler
6 */
7
8/*
9 *  Copyright (C) 2011 Petr Benes.
10 *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
11 *
12 *  The license and distribution terms for this file may be
13 *  found in the file LICENSE in this distribution or at
14 *  http://www.rtems.org/license/LICENSE.
15 */
16
17#if HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <rtems/score/scheduleredfimpl.h>
22#include <rtems/score/schedulerimpl.h>
23#include <rtems/score/thread.h>
24
25void _Scheduler_EDF_Unblock(
26  const Scheduler_Control *scheduler,
27  Thread_Control          *the_thread
28)
29{
30  _Scheduler_EDF_Enqueue( scheduler, the_thread);
31  /* TODO: flash critical section? */
32
33  /*
34   *  If the thread that was unblocked is more important than the heir,
35   *  then we have a new heir.  This may or may not result in a
36   *  context switch.
37   *
38   *  Normal case:
39   *    If the current thread is preemptible, then we need to do
40   *    a context switch.
41   *  Pseudo-ISR case:
42   *    Even if the thread isn't preemptible, if the new heir is
43   *    a pseudo-ISR system task, we need to do a context switch.
44   */
45  if ( _Scheduler_Is_priority_lower_than(
46         scheduler,
47         _Thread_Heir->current_priority,
48         the_thread->current_priority )) {
49    _Thread_Heir = the_thread;
50    if ( _Thread_Executing->is_preemptible ||
51         the_thread->current_priority == 0 )
52      _Thread_Dispatch_necessary = true;
53  }
54}
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