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

4.115
Last change on this file since 25f5730f was f39f667a, checked in by Sebastian Huber <sebastian.huber@…>, on 05/14/14 at 11:50:48

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: 922 bytes
Line 
1/**
2 * @file
3 *
4 * @ingroup ScoreSchedulerSMP
5 *
6 * @brief SMP Scheduler Implementation
7 */
8
9/*
10 * Copyright (c) 2014 embedded brains GmbH.  All rights reserved.
11 *
12 *  embedded brains GmbH
13 *  Dornierstr. 4
14 *  82178 Puchheim
15 *  Germany
16 *  <rtems@embedded-brains.de>
17 *
18 * The license and distribution terms for this file may be
19 * found in the file LICENSE in this distribution or at
20 * http://www.rtems.org/license/LICENSE.
21 */
22
23#if HAVE_CONFIG_H
24  #include "config.h"
25#endif
26
27#include <rtems/score/schedulerpriorityimpl.h>
28
29/*
30 * Table with all valid state transitions.  It is used in
31 * _Scheduler_SMP_Node_change_state() in case RTEMS_DEBUG is defined.
32 */
33const bool _Scheduler_SMP_Node_valid_state_changes[ 3 ][ 3 ] = {
34  /* FROM / TO       BLOCKED SCHEDULED READY */
35  /* BLOCKED    */ { false,  true,     true },
36  /* SCHEDULED  */ { true,   false,    true },
37  /* READY      */ { true,   true,     false }
38};
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