source: rtems/cpukit/score/src/schedulerprioritychangepriority.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: 1.3 KB
Line 
1/**
2 * @file
3 *
4 * @brief Removes Thread from Thread Queue
5 *
6 * @ingroup ScoreScheduler
7 */
8
9/*
10 *  COPYRIGHT (c) 2011.
11 *  On-Line Applications Research Corporation (OAR).
12 *
13 *  The license and distribution terms for this file may be
14 *  found in the file LICENSE in this distribution or at
15 *  http://www.rtems.org/license/LICENSE.
16 */
17
18#if HAVE_CONFIG_H
19#include "config.h"
20#endif
21
22#include <rtems/score/schedulerpriorityimpl.h>
23
24void _Scheduler_priority_Change_priority(
25  const Scheduler_Control *scheduler,
26  Thread_Control          *the_thread,
27  Priority_Control         new_priority,
28  bool                     prepend_it
29)
30{
31  Scheduler_priority_Context *context =
32    _Scheduler_priority_Get_context( scheduler );
33  Scheduler_priority_Node *node = _Scheduler_priority_Node_get( the_thread );
34
35  _Scheduler_priority_Ready_queue_extract(
36    the_thread,
37    &node->Ready_queue,
38    &context->Bit_map
39  );
40
41  _Scheduler_priority_Ready_queue_update(
42    &node->Ready_queue,
43    new_priority,
44    &context->Bit_map,
45    &context->Ready[ 0 ]
46  );
47
48  if ( prepend_it ) {
49    _Scheduler_priority_Ready_queue_enqueue_first(
50      the_thread,
51      &node->Ready_queue,
52      &context->Bit_map
53    );
54  } else {
55    _Scheduler_priority_Ready_queue_enqueue(
56      the_thread,
57      &node->Ready_queue,
58      &context->Bit_map
59    );
60  }
61}
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