Ticket #1906: cbs_scheduler4.diff

cpukit/sapi/Makefile.am

@@ -15 +15 @@
 include_rtems_HEADERS += include/rtems/init.h
 include_rtems_HEADERS += include/rtems/io.h
 include_rtems_HEADERS += include/rtems/mptables.h
+include_rtems_HEADERS += include/rtems/cbs.h
 include_rtems_HEADERS += include/rtems/rbtree.h
 include_rtems_HEADERS += include/rtems/sptables.h
 
@@ -22 +23 @@
 
 include_rtems_HEADERS += inline/rtems/chain.inl
 include_rtems_HEADERS += inline/rtems/extension.inl
+include_rtems_HEADERS += inline/rtems/cbs.inl
 include_rtems_HEADERS += inline/rtems/rbtree.inl
 
 ## src

cpukit/sapi/include/confdefs.h

@@ -574 +574 @@
  *  CONFIGURE_SCHEDULER_SIMPLE     - Light-weight Priority Scheduler
  *  CONFIGURE_SCHEDULER_SIMPLE_SMP - Simple SMP Priority Scheduler
  *  CONFIGURE_SCHEDULER_EDF        - EDF Scheduler
+ *  CONFIGURE_SCHEDULER_CBS        - CBS Scheduler
  * 
  * If no configuration is specified by the application, then 
  * CONFIGURE_SCHEDULER_PRIORITY is assumed to be the default.
@@ -600 +601 @@
     !defined(CONFIGURE_SCHEDULER_PRIORITY) && \
     !defined(CONFIGURE_SCHEDULER_SIMPLE) && \
     !defined(CONFIGURE_SCHEDULER_SIMPLE_SMP) && \
-    !defined(CONFIGURE_SCHEDULER_EDF)
+    !defined(CONFIGURE_SCHEDULER_EDF) && \
+    !defined(CONFIGURE_SCHEDULER_CBS)
   #if defined(RTEMS_SMP) && defined(CONFIGURE_SMP_APPLICATION)
     #define CONFIGURE_SCHEDULER_SIMPLE_SMP
   #else
@@ -676 +678 @@
     _Configure_From_workspace(sizeof(Scheduler_EDF_Per_thread)))
 #endif
 
+/*
+ * If the CBS Scheduler is selected, then configure for it.
+ */
+#if defined(CONFIGURE_SCHEDULER_CBS)
+  #include <rtems/score/schedulercbs.h>
+  #define CONFIGURE_SCHEDULER_ENTRY_POINTS SCHEDULER_CBS_ENTRY_POINTS
+
+  #ifndef CONFIGURE_CBS_MAXIMUM_SERVERS
+    #define CONFIGURE_CBS_MAXIMUM_SERVERS CONFIGURE_MAXIMUM_TASKS
+  #endif
+
+  #ifdef CONFIGURE_INIT
+    uint32_t _Scheduler_CBS_Maximum_servers = CONFIGURE_CBS_MAXIMUM_SERVERS;
+  #endif
+
+  /**
+   * define the memory used by the CBS scheduler
+   */
+  #define CONFIGURE_MEMORY_FOR_SCHEDULER ( \
+    _Configure_From_workspace((sizeof(Scheduler_CBS_Server) + \
+        sizeof(Scheduler_CBS_Server*)) * CONFIGURE_CBS_MAXIMUM_SERVERS))
+  #define CONFIGURE_MEMORY_PER_TASK_FOR_SCHEDULER ( \
+    _Configure_From_workspace(sizeof(Scheduler_CBS_Per_thread)))
+#endif
+
 #if defined(CONFIGURE_SCHEDULER_USER)
   #define CONFIGURE_SCHEDULER_ENTRY_POINTS \
           CONFIGURE_SCHEDULER_USER_ENTRY_POINTS

new file cpukit/sapi/include/rtems/cbs.h

@@ +1 @@
+/**
+ * @file rtems/cbs.h
+ *
+ *  This include file contains all the constants and structures associated
+ *  with the CBS library in RTEMS.
+ */
+
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#ifndef CONFIGURE_SCHEDULER_CBS
+  #error "cbs.h available only with CONFIGURE_SCHEDULER_CBS"
+#endif
+
+#ifndef _RTEMS_CBS_H
+#define _RTEMS_CBS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <rtems/score/schedulercbs.h>
+
+/* Return codes. */
+#define RTEMS_CBS_OK                       SCHEDULER_CBS_OK
+#define RTEMS_CBS_ERROR_GENERIC            SCHEDULER_CBS_ERROR_GENERIC
+#define RTEMS_CBS_ERROR_NO_MEMORY          SCHEDULER_CBS_ERROR_NO_MEMORY
+#define RTEMS_CBS_ERROR_INVALID_PARAMETER  SCHEDULER_CBS_ERROR_INVALID_PARAM
+#define RTEMS_CBS_ERROR_UNAUTHORIZED       SCHEDULER_CBS_ERROR_UNAUTHORIZED
+#define RTEMS_CBS_ERROR_UNIMPLEMENTED      SCHEDULER_CBS_ERROR_UNIMPLEMENTED
+#define RTEMS_CBS_ERROR_MISSING_COMPONENT  SCHEDULER_CBS_ERROR_MISSING_COMPONENT
+#define RTEMS_CBS_ERROR_INCONSISTENT_STATE SCHEDULER_CBS_ERROR_INCONSISTENT_STATE
+#define RTEMS_CBS_ERROR_SYSTEM_OVERLOAD    SCHEDULER_CBS_ERROR_SYSTEM_OVERLOAD
+#define RTEMS_CBS_ERROR_INTERNAL_ERROR     SCHEDULER_CBS_ERROR_INTERNAL_ERROR
+#define RTEMS_CBS_ERROR_NOT_FOUND          SCHEDULER_CBS_ERROR_NOT_FOUND
+#define RTEMS_CBS_ERROR_FULL               SCHEDULER_CBS_ERROR_FULL
+#define RTEMS_CBS_ERROR_EMPTY              SCHEDULER_CBS_ERROR_EMPTY
+#define RTEMS_CBS_ERROR_NOSERVER           SCHEDULER_CBS_ERROR_NOSERVER
+
+/** Callback function invoked when a budget overrun of a task occurs. */
+typedef Scheduler_CBS_Budget_overrun rtems_cbs_budget_overrun;
+
+/** Server id. */
+typedef Scheduler_CBS_Server_id rtems_cbs_server_id;
+
+/** Server parameters. */
+typedef Scheduler_CBS_Parameters rtems_cbs_parameters;
+
+#include <rtems/cbs.inl>
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/* end of include file */

new file cpukit/sapi/inline/rtems/cbs.inl

@@ +1 @@
+/**
+ * @file cbs.inl
+ *
+ *  This include file contains all the constants and structures associated
+ *  with the CBS library.
+ *
+ */
+
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#ifndef _RTEMS_CBS_H
+# error "Never use <rtems/cbs.inl> directly; include <rtems/cbs.h> instead."
+#endif
+
+#include <rtems/score/schedulercbs.h>
+
+/**
+ *  @brief rtems cbs init
+ *
+ *  Initializes the CBS library.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_initialize ( void )
+{
+  return _Scheduler_CBS_Initialize();
+}
+
+/**
+ *  @brief rtems cbs cleanup
+ *
+ *  Cleanup resources associated to the CBS Library.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_cleanup ( void )
+{
+  return _Scheduler_CBS_Cleanup();
+}
+
+/**
+ *  @brief rtems cbs create server
+ *
+ *  Create a new server with specified parameters.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_create_server (
+  rtems_cbs_parameters     *params,
+  rtems_cbs_budget_overrun  budget_overrun_callback,
+  rtems_cbs_server_id      *server_id
+)
+{
+  return _Scheduler_CBS_Create_server(
+             params,
+             budget_overrun_callback,
+             server_id
+         );
+}
+
+/**
+ *  @brief rtems cbs attach thread
+ *
+ *  Attach a task to an already existing server.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_attach_thread (
+  rtems_cbs_server_id server_id,
+  rtems_id            task_id
+)
+{
+  return _Scheduler_CBS_Attach_thread( server_id, task_id );
+}
+
+/**
+ *  @brief rtems cbs detach thread
+ *
+ *  Detach from the CBS Server.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_detach_thread (
+  rtems_cbs_server_id server_id,
+  rtems_id            task_id
+)
+{
+  return _Scheduler_CBS_Detach_thread( server_id, task_id );
+}
+
+/**
+ *  @brief rtems cbs destroy server
+ *
+ *  Detach all tasks from a server and destroy it.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_destroy_server (
+  rtems_cbs_server_id server_id
+)
+{
+  return _Scheduler_CBS_Destroy_server( server_id );
+}
+
+/**
+ *  @brief rtems cbs get server id
+ *
+ *  Get a thread server id, or RTEMS_CBS_E_NOT_FOUND if it is not
+ *  attached to any server.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_get_server_id (
+  rtems_id             task_id,
+  rtems_cbs_server_id *server_id
+)
+{
+  return _Scheduler_CBS_Get_server_id( task_id, server_id );
+}
+
+/**
+ *  @brief rtems cbs get parameters
+ *
+ *  Retrieve CBS scheduling parameters.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_get_parameters (
+  rtems_cbs_server_id   server_id,
+  rtems_cbs_parameters *params
+)
+{
+  return _Scheduler_CBS_Get_parameters( server_id, params );
+}
+
+/**
+ *  @brief rtems cbs set parameters
+ *
+ *  Change CBS scheduling parameters.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_set_parameters (
+  rtems_cbs_server_id   server_id,
+  rtems_cbs_parameters *params
+)
+{
+  return _Scheduler_CBS_Set_parameters( server_id, params );
+}
+
+/**
+ *  @brief rtems cbs get execution time
+ *
+ *  Retrieve time info relative to the current server.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_get_execution_time (
+  rtems_cbs_server_id    server_id,
+  time_t                *exec_time,
+  time_t                *abs_time
+)
+{
+  return _Scheduler_CBS_Get_execution_time( server_id, exec_time, abs_time );
+}
+
+/**
+ *  @brief rtems cbs get remaining budget
+ *
+ *  Retrieve remaining budget for the current server instance.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_get_remaining_budget (
+  rtems_cbs_server_id  server_id,
+  time_t              *remaining_budget
+)
+{
+  return _Scheduler_CBS_Get_remaining_budget( server_id, remaining_budget );
+}
+
+/**
+ *  @brief rtems cbs get approved budget
+ *
+ *  Retrieve the budget that has been approved for the subsequent
+ *  server instances.
+ *
+ *  @return status code.
+ */
+RTEMS_INLINE_ROUTINE int rtems_cbs_get_approved_budget (
+  rtems_cbs_server_id  server_id,
+  time_t              *appr_budget
+)
+{
+  return _Scheduler_CBS_Get_approved_budget( server_id, appr_budget );
+}

cpukit/score/Makefile.am

@@ -40 +40 @@
 include_rtems_score_HEADERS += include/rtems/score/prioritybitmap.h
 include_rtems_score_HEADERS += include/rtems/score/rbtree.h
 include_rtems_score_HEADERS += include/rtems/score/scheduler.h
+include_rtems_score_HEADERS += include/rtems/score/schedulercbs.h
 include_rtems_score_HEADERS += include/rtems/score/scheduleredf.h
 include_rtems_score_HEADERS += include/rtems/score/schedulerpriority.h
 include_rtems_score_HEADERS += include/rtems/score/schedulersimple.h
@@ -238 +239 @@
     src/scheduleredfupdate.c \
     src/scheduleredfyield.c
 
+## SCHEDULERCBS_C_FILES
+libscore_a_SOURCES += src/schedulercbs.c \
+    src/schedulercbsattachthread.c \
+    src/schedulercbscleanup.c \
+    src/schedulercbscreateserver.c \
+    src/schedulercbsdestroyserver.c \
+    src/schedulercbsdetachthread.c \
+    src/schedulercbsgetapprovedbudget.c \
+    src/schedulercbsgetexecutiontime.c \
+    src/schedulercbsgetparameters.c \
+    src/schedulercbsgetremainingbudget.c \
+    src/schedulercbsgetserverid.c \
+    src/schedulercbssetparameters.c \
+    src/schedulercbsreleasejob.c \
+    src/schedulercbsunblock.c
+
 ## PROTECTED_HEAP_C_FILES
 libscore_a_SOURCES += src/pheapallocate.c \
     src/pheapextend.c src/pheapfree.c src/pheapgetsize.c \

new file cpukit/score/include/rtems/score/schedulercbs.h

@@ +1 @@
+/**
+ *  @file  rtems/score/schedulercbs.h
+ *
+ *  This include file contains all the constants and structures associated
+ *  with the manipulation of threads for the CBS scheduler.
+ */
+
+/*
+ *  Copryight (c) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#ifndef _RTEMS_SCORE_SCHEDULERCBS_H
+#define _RTEMS_SCORE_SCHEDULERCBS_H
+
+#include <rtems/score/chain.h>
+#include <rtems/score/priority.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/rbtree.h>
+#include <rtems/score/scheduleredf.h>
+#include <rtems/rtems/signal.h>
+#include <rtems/rtems/timer.h>
+#include <rtems/score/thread.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  @addtogroup ScoreScheduler
+ *
+ */
+/**@{*/
+
+/**
+ *  Entry points for the Constant Bandwidth Server Scheduler.
+ *
+ *  @note: The CBS scheduler is an enhancement of EDF scheduler,
+ *         therefor some routines are similar.
+ */
+#define SCHEDULER_CBS_ENTRY_POINTS \
+  { \
+    _Scheduler_EDF_Initialize,       /* initialize entry point */ \
+    _Scheduler_EDF_Schedule,         /* schedule entry point */ \
+    _Scheduler_EDF_Yield,            /* yield entry point */ \
+    _Scheduler_EDF_Block,            /* block entry point */ \
+    _Scheduler_CBS_Unblock,          /* unblock entry point */ \
+    _Scheduler_EDF_Allocate,         /* allocate entry point */ \
+    _Scheduler_EDF_Free,             /* free entry point */ \
+    _Scheduler_EDF_Update,           /* update entry point */ \
+    _Scheduler_EDF_Enqueue,          /* enqueue entry point */ \
+    _Scheduler_EDF_Enqueue_first,    /* enqueue_first entry point */ \
+    _Scheduler_EDF_Extract,          /* extract entry point */ \
+    _Scheduler_EDF_Priority_compare, /* compares two priorities */ \
+    _Scheduler_CBS_Release_job,      /* new period of task */ \
+    _Scheduler_priority_Tick         /* tick entry point */ \
+  }
+
+/* Return values for CBS server. */
+#define SCHEDULER_CBS_OK                        0
+#define SCHEDULER_CBS_ERROR_GENERIC            -16
+#define SCHEDULER_CBS_ERROR_NO_MEMORY          -17
+#define SCHEDULER_CBS_ERROR_INVALID_PARAMETER  -18
+#define SCHEDULER_CBS_ERROR_UNAUTHORIZED       -19
+#define SCHEDULER_CBS_ERROR_UNIMPLEMENTED      -20
+#define SCHEDULER_CBS_ERROR_MISSING_COMPONENT  -21
+#define SCHEDULER_CBS_ERROR_INCONSISTENT_STATE -22
+#define SCHEDULER_CBS_ERROR_SYSTEM_OVERLOAD    -23
+#define SCHEDULER_CBS_ERROR_INTERNAL_ERROR     -24
+#define SCHEDULER_CBS_ERROR_NOT_FOUND          -25
+#define SCHEDULER_CBS_ERROR_FULL               -26
+#define SCHEDULER_CBS_ERROR_EMPTY              -27
+#define SCHEDULER_CBS_ERROR_NOSERVER           SCHEDULER_CBS_ERROR_NOT_FOUND
+
+/** Maximum number of simultaneous servers. */
+extern uint32_t _Scheduler_CBS_Maximum_servers;
+
+/** Server id. */
+typedef uint32_t Scheduler_CBS_Server_id;
+
+/** Callback function invoked when a budget overrun of a task occurs. */
+typedef void (*Scheduler_CBS_Budget_overrun)(
+    Scheduler_CBS_Server_id server_id
+);
+
+/**
+ * This structure handles server parameters.
+ */
+typedef struct {
+  /** Relative deadline of the server. */
+  time_t deadline;
+  /** Budget (computation time) of the server. */
+  time_t budget;
+} Scheduler_CBS_Parameters;
+
+/**
+ * This structure represents a time server.
+ */
+typedef struct {
+  /**
+   * Task id.
+   *
+   * @note: The current implementation of CBS handles only one task per server.
+   */
+  rtems_id                 task_id;
+  /** Server paramenters. */
+  Scheduler_CBS_Parameters parameters;
+  /** Callback function invoked when a budget overrun occurs. */
+  Scheduler_CBS_Budget_overrun  cbs_budget_overrun;
+} Scheduler_CBS_Server;
+
+/**
+ * This structure handles CBS specific data of a thread.
+ */
+typedef struct {
+  /** EDF scheduler specific data of a task. */
+  Scheduler_EDF_Per_thread      edf_per_thread;
+  /** CBS server specific data of a task. */
+  Scheduler_CBS_Server         *cbs_server;
+} Scheduler_CBS_Per_thread;
+
+
+/**
+ * List of servers. The @a Scheduler_CBS_Server is the index to the array
+ * of pointers to @a _Scheduler_CBS_Server_list.
+ */
+Scheduler_CBS_Server **_Scheduler_CBS_Server_list;
+
+/**
+ *  @brief Scheduler CBS Unblock
+ *
+ *  This routine adds @a the_thread to the scheduling decision, that is,
+ *  adds it to the ready queue and updates any appropriate scheduling
+ *  variables, for example the heir thread.
+ *
+ *  It is checked whether the remaining budget is sufficient. If not, the
+ *  thread continues as a new job in order to protect concurrent threads.
+ *
+ *  @note This has to be asessed as missed deadline of the current job.
+ *
+ *  @param[in] the_thread will be unblocked.
+ */
+void _Scheduler_CBS_Unblock(
+  Thread_Control    *the_thread
+);
+
+/**
+ *  @brief Scheduler CBS Release job
+ *
+ *  This routine is called when a new job of task is released.
+ *  It is called only from Rate Monotonic manager in the beginning
+ *  of new period. Deadline has to be shifted and budget replenished.
+ *
+ *  @param[in] the_thread is the owner of the job.
+ *  @param[in] length of the new job from now. If equal to 0,
+ *             the job was cancelled or deleted.
+ */
+
+void _Scheduler_CBS_Release_job (
+  Thread_Control  *the_thread,
+  uint32_t         length
+);
+
+/**
+ *  @brief _Scheduler_CBS_Initialize
+ *
+ *  Initializes the CBS library.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Initialize(void);
+
+/**
+ *  @brief _Scheduler_CBS_Attach_thread
+ *
+ *  Attach a task to an already existing server.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Attach_thread (
+  Scheduler_CBS_Server_id server_id,
+  rtems_id                task_id
+);
+
+/**
+ *  @brief _Scheduler_CBS_Detach_thread
+ *
+ *  Detach from the CBS Server.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Detach_thread (
+  Scheduler_CBS_Server_id server_id,
+  rtems_id                task_id
+);
+
+/**
+ *  @brief _Scheduler_CBS_Cleanup
+ *
+ *  Cleanup resources associated to the CBS Library.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Cleanup (void);
+
+/**
+ *  @brief _Scheduler_CBS_Create_server
+ *
+ *  Create a new server with specified parameters.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Create_server (
+  Scheduler_CBS_Parameters     *params,
+  Scheduler_CBS_Budget_overrun  budget_overrun_callback,
+  rtems_id                     *server_id
+);
+
+/**
+ *  @brief _Scheduler_CBS_Destroy_server
+ *
+ *  Detach all tasks from a server and destroy it.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Destroy_server (
+  Scheduler_CBS_Server_id server_id
+);
+
+/**
+ *  @brief _Scheduler_CBS_Get_approved_budget
+ *
+ *  Retrieve the budget that has been approved for the subsequent
+ *  server instances.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Get_approved_budget (
+  Scheduler_CBS_Server_id  server_id,
+  time_t                  *approved_budget
+);
+
+/**
+ *  @brief _Scheduler_CBS_Get_remaining_budget
+ *
+ *  Retrieve remaining budget for the current server instance.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Get_remaining_budget (
+  Scheduler_CBS_Server_id  server_id,
+  time_t                  *remaining_budget
+);
+
+/**
+ *  @brief _Scheduler_CBS_Get_execution_time
+ *
+ *  Retrieve time info relative to the current server.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Get_execution_time (
+  Scheduler_CBS_Server_id   server_id,
+  time_t                   *exec_time,
+  time_t                   *abs_time
+);
+
+/**
+ *  @brief _Scheduler_CBS_Get_parameters
+ *
+ *  Retrieve CBS scheduling parameters.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Get_parameters (
+  Scheduler_CBS_Server_id   server_id,
+  Scheduler_CBS_Parameters *params
+);
+
+/**
+ *  @brief _Scheduler_CBS_Get_server_id
+ *
+ *  Get a thread server id, or SCHEDULER_CBS_ERROR_NOT_FOUND if it is not
+ *  attached to any server.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Get_server_id (
+  rtems_id                 task_id,
+  Scheduler_CBS_Server_id *server_id
+);
+
+/**
+ *  @brief _Scheduler_CBS_Set_parameters
+ *
+ *  Change CBS scheduling parameters.
+ *
+ *  @return status code.
+ */
+int _Scheduler_CBS_Set_parameters (
+  Scheduler_CBS_Server_id   server_id,
+  Scheduler_CBS_Parameters *parameters
+);
+
+/**
+ *  @brief Scheduler CBS Budget overrun
+ *
+ *  This routine is invoked when a limited time quantum is exceeded.
+ */
+Thread_CPU_budget_algorithm_callout _Scheduler_CBS_Budget_callout(
+  Thread_Control *the_thread
+);
+
+#ifdef __cplusplus
+}
+#endif
+
+/**@}*/
+
+#endif
+/* end of include file */

new file cpukit/score/src/schedulercbs.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+#include <rtems/rtems/signal.h>
+
+Thread_CPU_budget_algorithm_callout _Scheduler_CBS_Budget_callout(
+  Thread_Control *the_thread
+)
+{
+  Priority_Control          new_priority;
+  Scheduler_CBS_Per_thread *sched_info;
+  Scheduler_CBS_Server_id   server_id;
+
+  /* Put violating task to background until the end of period. */
+  new_priority = the_thread->Start.initial_priority;
+  if ( the_thread->real_priority != new_priority )
+    the_thread->real_priority = new_priority;
+  if ( the_thread->current_priority != new_priority )
+    _Thread_Change_priority(the_thread, new_priority, true);
+
+  /* Invoke callback function if any. */
+  sched_info = (Scheduler_CBS_Per_thread *) the_thread->scheduler_info;
+  if ( sched_info->cbs_server->cbs_budget_overrun ) {
+    _Scheduler_CBS_Get_server_id(
+        sched_info->cbs_server->task_id,
+        &server_id
+    );
+    sched_info->cbs_server->cbs_budget_overrun( server_id );
+  }
+}
+
+int _Scheduler_CBS_Initialize(void)
+{
+  unsigned int i;
+  _Scheduler_CBS_Server_list = (Scheduler_CBS_Server **) _Workspace_Allocate(
+      _Scheduler_CBS_Maximum_servers * sizeof(Scheduler_CBS_Server*) );
+  if ( !_Scheduler_CBS_Server_list )
+    return SCHEDULER_CBS_ERROR_NO_MEMORY;
+  for (i = 0; i<_Scheduler_CBS_Maximum_servers; i++) {
+    _Scheduler_CBS_Server_list[i] = NULL;
+  }
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsattachthread.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+#include <rtems/rtems/object.h>
+
+int _Scheduler_CBS_Attach_thread (
+  Scheduler_CBS_Server_id server_id,
+  rtems_id                task_id
+)
+{
+  Objects_Locations location;
+  Thread_Control *the_thread;
+  Scheduler_CBS_Per_thread *sched_info;
+
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  the_thread = _Thread_Get(task_id, &location);
+  /* The routine _Thread_Get may disable dispatch and not enable again. */
+  if ( the_thread )
+    _Thread_Enable_dispatch();
+  if ( !the_thread )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  sched_info = (Scheduler_CBS_Per_thread *) the_thread->scheduler_info;
+
+  /* Thread is already attached to a server. */
+  if ( sched_info->cbs_server )
+    return SCHEDULER_CBS_ERROR_FULL;
+
+  /* Server is not valid. */
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+
+  /* Server is already attached to a thread. */
+  if ( _Scheduler_CBS_Server_list[server_id]->task_id != -1 )
+    return SCHEDULER_CBS_ERROR_FULL;
+
+  _Scheduler_CBS_Server_list[server_id]->task_id = task_id;
+  sched_info->cbs_server = (void *) _Scheduler_CBS_Server_list[server_id];
+
+  the_thread->budget_callout   = &_Scheduler_CBS_Budget_callout;
+  the_thread->budget_algorithm = THREAD_CPU_BUDGET_ALGORITHM_CALLOUT;
+  the_thread->is_preemptible   = true;
+
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbscleanup.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Cleanup (void)
+{
+  unsigned int i;
+
+  for ( i = 0; i<_Scheduler_CBS_Maximum_servers; i++ ) {
+    if ( _Scheduler_CBS_Server_list[ i ] )
+      _Scheduler_CBS_Destroy_server( i );
+  }
+  _Workspace_Free( _Scheduler_CBS_Server_list );
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbscreateserver.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Create_server (
+  Scheduler_CBS_Parameters     *params,
+  Scheduler_CBS_Budget_overrun  budget_overrun_callback,
+  rtems_id                     *server_id
+)
+{
+  unsigned int i;
+  Scheduler_CBS_Server *the_server;
+
+  if ( params->budget <= 0 ||
+       params->deadline <= 0 ||
+       params->budget >= SCHEDULER_EDF_PRIO_MSB ||
+       params->deadline >= SCHEDULER_EDF_PRIO_MSB )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  for ( i = 0; i<_Scheduler_CBS_Maximum_servers; i++ ) {
+    if ( !_Scheduler_CBS_Server_list[i] )
+      break;
+  }
+
+  if ( i == _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_FULL;
+
+  *server_id = i;
+  _Scheduler_CBS_Server_list[*server_id] = (Scheduler_CBS_Server *)
+    _Workspace_Allocate( sizeof(Scheduler_CBS_Server) );
+  the_server = _Scheduler_CBS_Server_list[*server_id];
+  if ( !the_server )
+    return SCHEDULER_CBS_ERROR_NO_MEMORY;
+
+  the_server->parameters = *params;
+  the_server->task_id = -1;
+  the_server->cbs_budget_overrun = budget_overrun_callback;
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsdestroyserver.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Destroy_server (
+  Scheduler_CBS_Server_id server_id
+)
+{
+  int ret = SCHEDULER_CBS_OK;
+  rtems_id tid;
+
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+
+  if ( (tid = _Scheduler_CBS_Server_list[server_id]->task_id) != -1 )
+    ret = _Scheduler_CBS_Detach_thread ( server_id, tid );
+
+  _Workspace_Free( _Scheduler_CBS_Server_list[server_id] );
+  _Scheduler_CBS_Server_list[server_id] = NULL;
+  return ret;
+}

new file cpukit/score/src/schedulercbsdetachthread.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Detach_thread (
+  Scheduler_CBS_Server_id server_id,
+  rtems_id                task_id
+)
+{
+  Objects_Locations location;
+  Thread_Control *the_thread;
+  Scheduler_CBS_Per_thread *sched_info;
+
+  the_thread = _Thread_Get(task_id, &location);
+  /* The routine _Thread_Get may disable dispatch and not enable again. */
+  if ( the_thread ) {
+    _Thread_Enable_dispatch();
+    sched_info = (Scheduler_CBS_Per_thread *) the_thread->scheduler_info;
+  }
+
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+  if ( !the_thread )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+  /* Server is not valid. */
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+  /* Thread and server are not attached. */
+  if ( _Scheduler_CBS_Server_list[server_id]->task_id != task_id )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  _Scheduler_CBS_Server_list[server_id]->task_id = -1;
+  sched_info->cbs_server = NULL;
+
+  the_thread->budget_algorithm = the_thread->Start.budget_algorithm;
+  the_thread->budget_callout   = the_thread->Start.budget_callout;
+  the_thread->is_preemptible   = the_thread->Start.is_preemptible;
+
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsgetapprovedbudget.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Get_approved_budget (
+  Scheduler_CBS_Server_id  server_id,
+  time_t                  *approved_budget
+)
+{
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+
+  *approved_budget = _Scheduler_CBS_Server_list[server_id]->parameters.budget;
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsgetexecutiontime.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Get_execution_time (
+  Scheduler_CBS_Server_id   server_id,
+  time_t                   *exec_time,
+  time_t                   *abs_time
+)
+{
+  Objects_Locations location;
+  Thread_Control *the_thread;
+
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+  if ( !_Scheduler_CBS_Server_list[server_id]->task_id ) {
+    *exec_time = 0;
+    return SCHEDULER_CBS_OK;
+  }
+
+  the_thread = _Thread_Get(
+                 _Scheduler_CBS_Server_list[server_id]->task_id,
+                 &location
+               );
+  /* The routine _Thread_Get may disable dispatch and not enable again. */
+  if ( the_thread ) {
+    _Thread_Enable_dispatch();
+    *exec_time = _Scheduler_CBS_Server_list[server_id]->parameters.budget -
+      the_thread->cpu_time_budget;
+  }
+  else {
+    *exec_time = _Scheduler_CBS_Server_list[server_id]->parameters.budget;
+  }
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsgetparameters.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Get_parameters (
+  Scheduler_CBS_Server_id   server_id,
+  Scheduler_CBS_Parameters *params
+)
+{
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+
+  *params = _Scheduler_CBS_Server_list[server_id]->parameters;
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsgetremainingbudget.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Get_remaining_budget (
+  Scheduler_CBS_Server_id  server_id,
+  time_t                  *remaining_budget
+)
+{
+  Objects_Locations location;
+  Thread_Control *the_thread;
+
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+  if ( _Scheduler_CBS_Server_list[server_id]->task_id == -1 ) {
+    *remaining_budget = _Scheduler_CBS_Server_list[server_id]->parameters.budget;
+    return SCHEDULER_CBS_OK;
+  }
+
+  the_thread = _Thread_Get(
+                 _Scheduler_CBS_Server_list[server_id]->task_id,
+                 &location
+               );
+  /* The routine _Thread_Get may disable dispatch and not enable again. */
+  if ( the_thread ) {
+    _Thread_Enable_dispatch();
+    *remaining_budget = the_thread->cpu_time_budget;
+  }
+  else {
+    *remaining_budget = 0;
+  }
+
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsgetserverid.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Get_server_id (
+  rtems_id                 task_id,
+  Scheduler_CBS_Server_id *server_id
+)
+{
+  unsigned int i;
+  for ( i = 0; i<_Scheduler_CBS_Maximum_servers; i++ ) {
+    if ( _Scheduler_CBS_Server_list[i] &&
+         _Scheduler_CBS_Server_list[i]->task_id == task_id ) {
+      *server_id = i;
+      return SCHEDULER_CBS_OK;
+    }
+  }
+  return SCHEDULER_CBS_ERROR_NOSERVER;
+}

new file cpukit/score/src/schedulercbsreleasejob.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+void _Scheduler_CBS_Release_job(
+  Thread_Control    *the_thread,
+  uint32_t           deadline
+)
+{
+  Priority_Control new_priority;
+  Scheduler_CBS_Per_thread *sched_info =
+    (Scheduler_CBS_Per_thread *) the_thread->scheduler_info;
+  Scheduler_CBS_Server *serv_info =
+    (Scheduler_CBS_Server *) sched_info->cbs_server;
+
+  if (deadline) {
+    /* Initializing or shifting deadline. */
+    if (serv_info && serv_info->parameters.budget)
+      new_priority = (_Watchdog_Ticks_since_boot + serv_info->parameters.deadline)
+        & ~SCHEDULER_EDF_PRIO_MSB;
+    else
+      new_priority = (_Watchdog_Ticks_since_boot + deadline)
+        & ~SCHEDULER_EDF_PRIO_MSB;
+  }
+  else {
+    /* Switch back to background priority. */
+    new_priority = the_thread->Start.initial_priority;
+  }
+
+  /* Budget replenishment for the next job. */
+  if (serv_info && serv_info->parameters.budget)
+    the_thread->cpu_time_budget = serv_info->parameters.budget;
+
+  the_thread->real_priority = new_priority;
+  _Thread_Change_priority(the_thread, new_priority, true);
+}

new file cpukit/score/src/schedulercbssetparameters.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/config.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+int _Scheduler_CBS_Set_parameters (
+  Scheduler_CBS_Server_id   server_id,
+  Scheduler_CBS_Parameters *params
+)
+{
+  if ( server_id < 0 || server_id >= _Scheduler_CBS_Maximum_servers )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  if ( params->budget <= 0 ||
+       params->deadline <= 0 ||
+       params->budget >= SCHEDULER_EDF_PRIO_MSB ||
+       params->deadline >= SCHEDULER_EDF_PRIO_MSB )
+    return SCHEDULER_CBS_ERROR_INVALID_PARAMETER;
+
+  if ( !_Scheduler_CBS_Server_list[server_id] )
+    return SCHEDULER_CBS_ERROR_NOSERVER;
+
+  _Scheduler_CBS_Server_list[server_id]->parameters = *params;
+  return SCHEDULER_CBS_OK;
+}

new file cpukit/score/src/schedulercbsunblock.c

@@ +1 @@
+/*
+ *  Copyright (C) 2011 Petr Benes.
+ *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulercbs.h>
+
+void _Scheduler_CBS_Unblock(
+  Thread_Control    *the_thread
+)
+{
+  Scheduler_CBS_Per_thread *sched_info;
+  Scheduler_CBS_Server *serv_info;
+  Priority_Control new_priority;
+
+  _Scheduler_EDF_Enqueue(the_thread);
+  /* TODO: flash critical section? */
+
+  sched_info = (Scheduler_CBS_Per_thread *) the_thread->scheduler_info;
+  serv_info = (Scheduler_CBS_Server *) sched_info->cbs_server;
+
+  /*
+   * Late unblock rule for deadline-driven tasks. The remaining time to
+   * deadline must be sufficient to serve the remaining computation time
+   * without increased utilization of this task. It might cause a deadline
+   * miss of another task.
+   */
+  if (serv_info) {
+    time_t deadline = serv_info->parameters.deadline;
+    time_t budget = serv_info->parameters.budget;
+    time_t deadline_left = the_thread->cpu_time_budget;
+    time_t budget_left = the_thread->real_priority -
+                           _Watchdog_Ticks_since_boot;
+
+    if ( deadline*budget_left > budget*deadline_left ) {
+      /* Put late unblocked task to background until the end of period. */
+      new_priority = the_thread->Start.initial_priority;
+      if ( the_thread->real_priority != new_priority )
+        the_thread->real_priority = new_priority;
+      if ( the_thread->current_priority != new_priority )
+        _Thread_Change_priority(the_thread, new_priority, true);
+    }
+  }
+
+  /*
+   *  If the thread that was unblocked is more important than the heir,
+   *  then we have a new heir.  This may or may not result in a
+   *  context switch.
+   *
+   *  Normal case:
+   *    If the current thread is preemptible, then we need to do
+   *    a context switch.
+   *  Pseudo-ISR case:
+   *    Even if the thread isn't preemptible, if the new heir is
+   *    a pseudo-ISR system task, we need to do a context switch.
+   */
+  if ( _Scheduler_Is_priority_higher_than( the_thread->current_priority,
+       _Thread_Heir->current_priority)) {
+    _Thread_Heir = the_thread;
+    if ( _Thread_Executing->is_preemptible ||
+         the_thread->current_priority == 0 )
+      _Thread_Dispatch_necessary = true;
+  }
+}