source: rtems/cpukit/score/src/schedulersimpleyield.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: 967 bytes
Line 
1/**
2 * @file
3 *
4 * @brief Simple Schedule Yield CPU
5 * @ingroup ScoreScheduler
6 */
7
8/*
9 *  COPYRIGHT (c) 2011.
10 *  On-Line Applications Research Corporation (OAR).
11 *
12 *  The license and distribution terms for this file may be
13 *  found in 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/schedulersimpleimpl.h>
22#include <rtems/score/isr.h>
23
24void _Scheduler_simple_Yield(
25  const Scheduler_Control *scheduler,
26  Thread_Control          *the_thread
27)
28{
29  Scheduler_simple_Context *context =
30    _Scheduler_simple_Get_context( scheduler );
31  ISR_Level       level;
32
33  _ISR_Disable( level );
34
35    _Chain_Extract_unprotected( &the_thread->Object.Node );
36    _Scheduler_simple_Insert_priority_fifo( &context->Ready, the_thread );
37
38    _ISR_Flash( level );
39
40    _Scheduler_simple_Schedule_body( scheduler, the_thread, false );
41
42  _ISR_Enable( level );
43}
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