[PATCH v4] Pre-Release Strong-APA

Richi Dubey richidubey at gmail.com
Wed Aug 26 20:38:55 UTC 2020


I used this command:

richi at YouAreAmazing:~/quick-start/src/rtems$ git send-email --to=
devel at rtems.org v4-0001-Pre-Release-Strong-APA.patch
v4-0001-Pre-Release-Strong-APA.patch
(mbox) Adding cc: Richi Dubey <richidubey at gmail.com> from line 'From: Richi
Dubey <richidubey at gmail.com>'

From: Richi Dubey <richidubey at gmail.com>
To: devel at rtems.org
Cc: Richi Dubey <richidubey at gmail.com>
Subject: [PATCH v4] Pre-Release Strong-APA
Date: Thu, 27 Aug 2020 02:03:33 +0530
Message-Id: <20200826203333.8491-1-richidubey at gmail.com>
X-Mailer: git-send-email 2.17.1

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From: Richi Dubey <richidubey at gmail.com>
To: devel at rtems.org
Cc: Richi Dubey <richidubey at gmail.com>
Subject: [PATCH v4] Pre-Release Strong-APA
Date: Thu, 27 Aug 2020 02:03:33 +0530
Message-Id: <20200826203333.8491-1-richidubey at gmail.com>
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Result: 250

On Thu, Aug 27, 2020 at 2:07 AM Richi Dubey <richidubey at gmail.com> wrote:

> I've been trying to send the v4 but the patch keeps coming in v3 mail
> thread :(.
>
> What am I missing?
>
> On Thu, Aug 27, 2020 at 2:03 AM Richi Dubey <richidubey at gmail.com> wrote:
>
>> ---
>>  cpukit/include/rtems/scheduler.h              |   6 +-
>>  .../include/rtems/score/schedulerstrongapa.h  | 152 ++-
>>  cpukit/score/src/schedulerstrongapa.c         | 901 ++++++++++++++----
>>  3 files changed, 828 insertions(+), 231 deletions(-)
>>
>> diff --git a/cpukit/include/rtems/scheduler.h
>> b/cpukit/include/rtems/scheduler.h
>> index 955a83cfb4..6a05c2798a 100644
>> --- a/cpukit/include/rtems/scheduler.h
>> +++ b/cpukit/include/rtems/scheduler.h
>> @@ -257,16 +257,14 @@
>>    #define RTEMS_SCHEDULER_STRONG_APA( name, prio_count ) \
>>      static struct { \
>>        Scheduler_strong_APA_Context Base; \
>> -      Chain_Control                Ready[ ( prio_count ) ]; \
>> +      Scheduler_strong_APA_CPU CPU[ CONFIGURE_MAXIMUM_PROCESSORS ]; \
>>      } SCHEDULER_STRONG_APA_CONTEXT_NAME( name )
>>
>>    #define RTEMS_SCHEDULER_TABLE_STRONG_APA( name, obj_name ) \
>>      { \
>>        &SCHEDULER_STRONG_APA_CONTEXT_NAME( name ).Base.Base.Base, \
>>        SCHEDULER_STRONG_APA_ENTRY_POINTS, \
>> -      RTEMS_ARRAY_SIZE( \
>> -        SCHEDULER_STRONG_APA_CONTEXT_NAME( name ).Ready \
>> -      ) - 1, \
>> +      SCHEDULER_STRONG_APA_MAXIMUM_PRIORITY, \
>>        ( obj_name ) \
>>        SCHEDULER_CONTROL_IS_NON_PREEMPT_MODE_SUPPORTED( false ) \
>>      }
>> diff --git a/cpukit/include/rtems/score/schedulerstrongapa.h
>> b/cpukit/include/rtems/score/schedulerstrongapa.h
>> index 0ac28cb439..cfd79e932a 100644
>> --- a/cpukit/include/rtems/score/schedulerstrongapa.h
>> +++ b/cpukit/include/rtems/score/schedulerstrongapa.h
>> @@ -6,31 +6,47 @@
>>   * @brief Strong APA Scheduler API
>>   */
>>
>> -/*
>> - * Copyright (c) 2013, 2018 embedded brains GmbH.  All rights reserved.
>> +/* SPDX-License-Identifier: BSD-2-Clause
>>   *
>> - *  embedded brains GmbH
>> - *  Dornierstr. 4
>> - *  82178 Puchheim
>> - *  Germany
>> - *  <rtems at embedded-brains.de>
>> + * Copyright (C) 2020 Richi Dubey
>> + * Copyright (c) 2013, 2018 embedded brains GmbH
>>   *
>> - * The license and distribution terms for this file may be
>> - * found in the file LICENSE in this distribution or at
>> - * http://www.rtems.org/license/LICENSE.
>> + * Redistribution and use in source and binary forms, with or without
>> + * modification, are permitted provided that the following conditions
>> + * are met:
>> + * 1. Redistributions of source code must retain the above copyright
>> + *    notice, this list of conditions and the following disclaimer.
>> + * 2. Redistributions in binary form must reproduce the above copyright
>> + *    notice, this list of conditions and the following disclaimer in the
>> + *    documentation and/or other materials provided with the
>> distribution.
>> + *
>> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
>> "AS IS"
>> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
>> THE
>> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>> PURPOSE
>> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
>> BE
>> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
>> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
>> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
>> BUSINESS
>> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
>> IN
>> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
>> OTHERWISE)
>> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
>> OF THE
>> + * POSSIBILITY OF SUCH DAMAGE.
>>   */
>>
>>  #ifndef _RTEMS_SCORE_SCHEDULERSTRONGAPA_H
>>  #define _RTEMS_SCORE_SCHEDULERSTRONGAPA_H
>>
>>  #include <rtems/score/scheduler.h>
>> -#include <rtems/score/schedulerpriority.h>
>>  #include <rtems/score/schedulersmp.h>
>> +#include <rtems/score/percpu.h>
>>
>>  #ifdef __cplusplus
>>  extern "C" {
>>  #endif /* __cplusplus */
>>
>> +#define STRONG_SCHEDULER_NODE_OF_CHAIN( node ) \
>> +  RTEMS_CONTAINER_OF( node, Scheduler_strong_APA_Node, Ready_node )
>> +
>>  /**
>>   * @defgroup RTEMSScoreSchedulerStrongAPA Strong APA Scheduler
>>   *
>> @@ -38,42 +54,96 @@ extern "C" {
>>   *
>>   * @brief Strong APA Scheduler
>>   *
>> - * This is an implementation of the global fixed priority scheduler
>> (G-FP).  It
>> - * uses one ready chain per priority to ensure constant time insert
>> operations.
>> - * The scheduled chain uses linear insert operations and has at most
>> processor
>> - * count entries.  Since the processor and priority count are constants
>> all
>> - * scheduler operations complete in a bounded execution time.
>> - *
>> - * The the_thread preempt mode will be ignored.
>> + * This is an implementation of the Strong APA scheduler defined by
>> + * Cerqueira et al. in Linux's Processor Affinity API, Refined:
>> + * Shifting Real-Time Tasks Towards Higher Schedulability.
>>   *
>> + * The scheduled and ready nodes are accessed via the
>> + * Scheduler_strong_APA_Context::Ready which helps in backtracking when a
>> + * node which is executing on a CPU gets blocked. New node is allocated
>> to
>> + * the cpu by checking all the executing nodes in the affinity set of the
>> + * node and the subsequent nodes executing on the processors in its
>> + * affinity set.
>>   * @{
>>   */
>>
>>  /**
>> - * @brief Scheduler context specialization for Strong APA
>> - * schedulers.
>> + * @brief Scheduler node specialization for Strong APA schedulers.
>>   */
>>  typedef struct {
>> -  Scheduler_SMP_Context    Base;
>> -  Priority_bit_map_Control Bit_map;
>> -  Chain_Control            Ready[ RTEMS_ZERO_LENGTH_ARRAY ];
>> -} Scheduler_strong_APA_Context;
>> +  /**
>> +   * @brief SMP scheduler node.
>> +   */
>> +  Scheduler_SMP_Node Base;
>> +
>> + /**
>> +   * @brief Chain node for Scheduler_strong_APA_Context::Ready.
>> +   */
>> +  Chain_Node Ready_node;
>> +
>> +  /**
>> +   * @brief CPU that this node would preempt in the backtracking part of
>> +   * _Scheduler_strong_APA_Get_highest_ready and
>> +   * _Scheduler_strong_APA_Do_Enqueue.
>> +   */
>> +  Per_CPU_Control *cpu_to_preempt;
>> +
>> +  /**
>> +   * @brief The associated affinity set of this node.
>> +   */
>> +  Processor_mask Affinity;
>> +} Scheduler_strong_APA_Node;
>> +
>>
>>  /**
>> - * @brief Scheduler node specialization for Strong APA
>> - * schedulers.
>> + * @brief CPU related variables and a CPU_Control to implement BFS.
>> + */
>> +typedef struct
>> +{
>> +   /**
>> +   * @brief CPU in a queue.
>> +   */
>> +  Per_CPU_Control *cpu;
>> +
>> +  /**
>> +   * @brief The node that would preempt this CPU.
>> +   */
>> +  Scheduler_Node *preempting_node;
>> +
>> +   /**
>> +   * @brief Whether or not this cpu has been added to the queue
>> +   * (visited in BFS).
>> +   */
>> +  bool visited;
>> +
>> +  /**
>> +   * @brief The node currently executing on this cpu.
>> +   */
>> +   Scheduler_Node *executing;
>> +} Scheduler_strong_APA_CPU;
>> +
>> + /**
>> + * @brief Scheduler context and node definition for Strong APA scheduler.
>>   */
>>  typedef struct {
>> + /**
>> +   * @brief @see Scheduler_SMP_Context.
>> +   */
>> +  Scheduler_SMP_Context Base;
>> +
>>    /**
>> -   * @brief SMP scheduler node.
>> +   * @brief Chain of all the ready and scheduled nodes present in
>> +   * the Strong APA scheduler.
>>     */
>> -  Scheduler_SMP_Node Base;
>> +  Chain_Control Ready;
>>
>>    /**
>> -   * @brief The associated ready queue of this node.
>> +   * @brief Struct with important variables for each cpu.
>>     */
>> -  Scheduler_priority_Ready_queue Ready_queue;
>> -} Scheduler_strong_APA_Node;
>> +  Scheduler_strong_APA_CPU CPU[ RTEMS_ZERO_LENGTH_ARRAY ];
>> +} Scheduler_strong_APA_Context;
>> +
>> +#define SCHEDULER_STRONG_APA_MAXIMUM_PRIORITY 255
>>
>>  /**
>>   * @brief Entry points for the Strong APA Scheduler.
>> @@ -100,8 +170,8 @@ typedef struct {
>>      _Scheduler_default_Release_job, \
>>      _Scheduler_default_Cancel_job, \
>>      _Scheduler_default_Tick, \
>> -    _Scheduler_SMP_Start_idle \
>> -    SCHEDULER_OPERATION_DEFAULT_GET_SET_AFFINITY \
>> +    _Scheduler_SMP_Start_idle, \
>> +    _Scheduler_strong_APA_Set_affinity \
>>    }
>>
>>  /**
>> @@ -168,7 +238,7 @@ void _Scheduler_strong_APA_Update_priority(
>>  /**
>>   * @brief Asks for help.
>>   *
>> - * @param  scheduler The scheduler control instance.
>> + * @param scheduler The scheduler control instance.
>>   * @param the_thread The thread that asks for help.
>>   * @param node The node of @a the_thread.
>>   *
>> @@ -246,6 +316,20 @@ void _Scheduler_strong_APA_Yield(
>>    Scheduler_Node          *node
>>  );
>>
>> +/**
>> + * @brief Sets the affinity .
>> + *
>> + * @param scheduler The scheduler control instance.
>> + * @param the_thread The thread to yield.
>> + * @param[in, out] node The node of @a the_thread.
>> + */
>> +bool _Scheduler_strong_APA_Set_affinity(
>> +  const Scheduler_Control *scheduler,
>> +  Thread_Control          *thread,
>> +  Scheduler_Node          *node_base,
>> +  const Processor_mask    *affinity
>> +);
>> +
>>  /** @} */
>>
>>  #ifdef __cplusplus
>> diff --git a/cpukit/score/src/schedulerstrongapa.c
>> b/cpukit/score/src/schedulerstrongapa.c
>> index 924cd86412..429bbacece 100644
>> --- a/cpukit/score/src/schedulerstrongapa.c
>> +++ b/cpukit/score/src/schedulerstrongapa.c
>> @@ -6,18 +6,31 @@
>>   * @brief Strong APA Scheduler Implementation
>>   */
>>
>> -/*
>> - * Copyright (c) 2013, 2016 embedded brains GmbH.  All rights reserved.
>> +/* SPDX-License-Identifier: BSD-2-Clause
>> + *
>> + * Copyright (C) 2020 Richi Dubey
>> + * Copyright (c) 2013, 2018 embedded brains GmbH
>>   *
>> - *  embedded brains GmbH
>> - *  Dornierstr. 4
>> - *  82178 Puchheim
>> - *  Germany
>> - *  <rtems at embedded-brains.de>
>> + * Redistribution and use in source and binary forms, with or without
>> + * modification, are permitted provided that the following conditions
>> + * are met:
>> + * 1. Redistributions of source code must retain the above copyright
>> + *    notice, this list of conditions and the following disclaimer.
>> + * 2. Redistributions in binary form must reproduce the above copyright
>> + *    notice, this list of conditions and the following disclaimer in the
>> + *    documentation and/or other materials provided with the
>> distribution.
>>   *
>> - * The license and distribution terms for this file may be
>> - * found in the file LICENSE in this distribution or at
>> - * http://www.rtems.org/license/LICENSE.
>> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
>> "AS IS"
>> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
>> THE
>> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>> PURPOSE
>> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
>> BE
>> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
>> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
>> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
>> BUSINESS
>> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
>> IN
>> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
>> OTHERWISE)
>> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
>> OF THE
>> + * POSSIBILITY OF SUCH DAMAGE.
>>   */
>>
>>  #ifdef HAVE_CONFIG_H
>> @@ -25,301 +38,754 @@
>>  #endif
>>
>>  #include <rtems/score/schedulerstrongapa.h>
>> -#include <rtems/score/schedulerpriorityimpl.h>
>>  #include <rtems/score/schedulersmpimpl.h>
>> +#include <rtems/score/assert.h>
>>
>> -static Scheduler_strong_APA_Context *_Scheduler_strong_APA_Get_self(
>> -  Scheduler_Context *context
>> -)
>> +static inline Scheduler_strong_APA_Context *
>> +_Scheduler_strong_APA_Get_context( const Scheduler_Control *scheduler )
>> +{
>> +  return (Scheduler_strong_APA_Context *) _Scheduler_Get_context(
>> scheduler );
>> +}
>> +
>> +static inline Scheduler_strong_APA_Context *
>> +_Scheduler_strong_APA_Get_self( Scheduler_Context *context )
>>  {
>>    return (Scheduler_strong_APA_Context *) context;
>>  }
>>
>> -static Scheduler_strong_APA_Node *
>> +static inline Scheduler_strong_APA_Node *
>>  _Scheduler_strong_APA_Node_downcast( Scheduler_Node *node )
>>  {
>>    return (Scheduler_strong_APA_Node *) node;
>>  }
>>
>> -static void _Scheduler_strong_APA_Move_from_scheduled_to_ready(
>> +static inline void _Scheduler_strong_APA_Do_update(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *scheduled_to_ready
>> +  Scheduler_Node    *node,
>> +  Priority_Control   new_priority
>>  )
>>  {
>> -  Scheduler_strong_APA_Context *self =
>> -    _Scheduler_strong_APA_Get_self( context );
>> -  Scheduler_strong_APA_Node *node =
>> -    _Scheduler_strong_APA_Node_downcast( scheduled_to_ready );
>> -
>> -  _Chain_Extract_unprotected( &node->Base.Base.Node.Chain );
>> -  _Scheduler_priority_Ready_queue_enqueue_first(
>> -    &node->Base.Base.Node.Chain,
>> -    &node->Ready_queue,
>> -    &self->Bit_map
>> -  );
>> +  Scheduler_SMP_Node *smp_node;
>> +  (void) context;
>> +
>> +  smp_node = _Scheduler_SMP_Node_downcast( node );
>> +  _Scheduler_SMP_Node_update_priority( smp_node, new_priority );
>>  }
>>
>> -static void _Scheduler_strong_APA_Move_from_ready_to_scheduled(
>> +/*
>> + * Returns true if the Strong APA scheduler has ready nodes
>> + * available for scheduling.
>> + */
>> +static inline bool
>> +    _Scheduler_strong_APA_Has_ready( Scheduler_Context *context )
>> +{
>> +  Scheduler_strong_APA_Context *self;
>> +  const Chain_Node             *tail;
>> +  Chain_Node                   *next;
>> +  Scheduler_strong_APA_Node    *node;
>> +
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  tail = _Chain_Immutable_tail( &self->Ready );
>> +  next = _Chain_First( &self->Ready );
>> +
>> +  while ( next != tail ) {
>> +    node = (Scheduler_strong_APA_Node *) STRONG_SCHEDULER_NODE_OF_CHAIN(
>> next );
>> +
>> +    if (
>> +      _Scheduler_SMP_Node_state( &node->Base.Base ) ==
>> +      SCHEDULER_SMP_NODE_READY
>> +    ) {
>> +      return true;
>> +    }
>> +
>> +    next = _Chain_Next( next );
>> +  }
>> +
>> +  return false;
>> +}
>> +
>> +static inline void _Scheduler_strong_APA_Allocate_processor(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *ready_to_scheduled
>> +  Scheduler_Node    *scheduled_base,
>> +  Scheduler_Node    *victim_base,
>> +  Per_CPU_Control   *victim_cpu
>>  )
>>  {
>> +  Scheduler_strong_APA_Node    *scheduled;
>>    Scheduler_strong_APA_Context *self;
>> -  Scheduler_strong_APA_Node    *node;
>> -  Priority_Control              insert_priority;
>>
>> +  (void) victim_base;
>> +
>> +  scheduled = _Scheduler_strong_APA_Node_downcast( scheduled_base );
>>    self = _Scheduler_strong_APA_Get_self( context );
>> -  node = _Scheduler_strong_APA_Node_downcast( ready_to_scheduled );
>>
>> -  _Scheduler_priority_Ready_queue_extract(
>> -    &node->Base.Base.Node.Chain,
>> -    &node->Ready_queue,
>> -    &self->Bit_map
>> +  self->CPU[ _Per_CPU_Get_index( victim_cpu ) ].executing =
>> scheduled_base;
>> +
>> +  _Scheduler_SMP_Allocate_processor_exact(
>> +    context,
>> +    &(scheduled->Base.Base),
>> +    NULL,
>> +    victim_cpu
>>    );
>> -  insert_priority = _Scheduler_SMP_Node_priority( &node->Base.Base );
>> +}
>> +
>> +/*
>> + * Finds and returns the highest ready node present by accessing the
>> + * _Strong_APA_Context->CPU with front and rear values.
>> + */
>> +
>> +static inline Scheduler_Node * _Scheduler_strong_APA_Find_highest_ready(
>> +  Scheduler_strong_APA_Context *self,
>> +  uint32_t                      front,
>> +  uint32_t                      rear
>> +)
>> +{
>> +  Scheduler_Node              *highest_ready;
>> +  Scheduler_strong_APA_CPU    *CPU;
>> +  const Chain_Node            *tail;
>> +  Chain_Node                  *next;
>> +  uint32_t                     index_assigned_cpu;
>> +  Scheduler_strong_APA_Node   *node;
>> +  Priority_Control             min_priority_num;
>> +  Priority_Control             curr_priority;
>> +  Per_CPU_Control             *assigned_cpu;
>> +  Scheduler_SMP_Node_state     curr_state;
>> +  Per_CPU_Control             *curr_CPU;
>> +  bool                         first_task;
>> +
>> +  CPU = self->CPU;
>> +   /*
>> +    * When the first task accessed has nothing to compare its priority
>> against
>> +    * So, it is the task with the highest priority witnessed so far.
>> +   */
>> +  first_task = true;
>> +
>> +  //Assert rear < sizeof(Context->CPU)
>> +  _Assert( rear < CONFIGURE_MAXIMUM_PROCESSOR );
>> +
>> +  while( front <= rear ) {
>> +    curr_CPU = CPU[ front ].cpu;
>> +    front = front + 1;
>> +
>> +    tail = _Chain_Immutable_tail( &self->Ready );
>> +    next = _Chain_First( &self->Ready );
>> +
>> +    while ( next != tail ) {
>> +      node = (Scheduler_strong_APA_Node*)
>> STRONG_SCHEDULER_NODE_OF_CHAIN( next );
>> +      //Check if the curr_CPU is in the affinity set of the node.
>> +      if (
>> +        _Processor_mask_Is_set(&node->Affinity,
>> _Per_CPU_Get_index(curr_CPU))
>> +      ) {
>> +        curr_state = _Scheduler_SMP_Node_state( &node->Base.Base );
>> +
>> +        if ( curr_state == SCHEDULER_SMP_NODE_SCHEDULED ) {
>> +          assigned_cpu = _Thread_Get_CPU( node->Base.Base.user );
>> +          index_assigned_cpu =  _Per_CPU_Get_index( assigned_cpu );
>> +
>> +          if ( CPU[ index_assigned_cpu ].visited == false ) {
>> +            rear = rear + 1;
>> +            CPU[ rear ].cpu = assigned_cpu;
>> +            CPU[ index_assigned_cpu ].visited = true;
>> +            /*
>> +             * The curr CPU of the queue invoked this node to add its CPU
>> +             * that it is executing on to the queue. So this node might
>> get
>> +             * preempted because of the invoker curr_CPU and this
>> curr_CPU
>> +             * is the CPU that node should preempt in case this node
>> +             * gets preempted.
>> +             */
>> +            node->cpu_to_preempt = curr_CPU;
>> +          }
>> +        }
>> +        else if ( curr_state == SCHEDULER_SMP_NODE_READY ) {
>> +          curr_priority = _Scheduler_Node_get_priority( &node->Base.Base
>> );
>> +          curr_priority = SCHEDULER_PRIORITY_PURIFY( curr_priority );
>> +
>> +          if ( first_task == true || curr_priority < min_priority_num ) {
>> +            min_priority_num = curr_priority;
>> +           highest_ready = &node->Base.Base;
>> +           first_task = false;
>> +           /*
>> +            * In case curr_CPU is filter_CPU, we need to store the
>> +            * cpu_to_preempt value so that we go back to SMP_*
>> +            * function, rather than preempting the node ourselves.
>> +            */
>> +           node->cpu_to_preempt = curr_CPU;
>> +         }
>> +        }
>> +      }
>> +    next = _Chain_Next( next );
>> +    }
>> +  }
>> +
>> +  return highest_ready;
>> +}
>> +
>> +static inline void  _Scheduler_strong_APA_Move_from_ready_to_scheduled(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *ready_to_scheduled
>> +)
>> +{
>> +  Priority_Control insert_priority;
>> +
>> +  insert_priority = _Scheduler_SMP_Node_priority( ready_to_scheduled );
>>    insert_priority = SCHEDULER_PRIORITY_APPEND( insert_priority );
>> -  _Chain_Insert_ordered_unprotected(
>> -    &self->Base.Scheduled,
>> -    &node->Base.Base.Node.Chain,
>> -    &insert_priority,
>> -    _Scheduler_SMP_Priority_less_equal
>> +  _Scheduler_SMP_Insert_scheduled(
>> +    context,
>> +    ready_to_scheduled,
>> +    insert_priority
>>    );
>>  }
>>
>> -static void _Scheduler_strong_APA_Insert_ready(
>> +/*
>> + * Implement the BFS Algorithm for task departure to get the highest
>> ready task
>> + * for a particular CPU, returns the highest ready Scheduler_Node
>> + * Scheduler_Node filter here pointst to the victim node that is blocked
>> + * resulting which this function is called.
>> + */
>> +static inline Scheduler_Node *_Scheduler_strong_APA_Get_highest_ready(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *node_base,
>> -  Priority_Control   insert_priority
>> +  Scheduler_Node    *filter
>>  )
>>  {
>>    Scheduler_strong_APA_Context *self;
>> +  Per_CPU_Control              *filter_cpu;
>>    Scheduler_strong_APA_Node    *node;
>> +  Scheduler_Node               *highest_ready;
>> +  Scheduler_Node               *curr_node;
>> +  Scheduler_Node               *next_node;
>> +  Scheduler_strong_APA_CPU     *CPU;
>> +  uint32_t                     front;
>> +  uint32_t                     rear;
>> +  uint32_t                     cpu_max;
>> +  uint32_t                             cpu_index;
>>
>>    self = _Scheduler_strong_APA_Get_self( context );
>> -  node = _Scheduler_strong_APA_Node_downcast( node_base );
>> +  //Denotes front and rear of the queue.
>> +  front = 0;
>> +  rear = -1;
>>
>> -  if ( SCHEDULER_PRIORITY_IS_APPEND( insert_priority ) ) {
>> -    _Scheduler_priority_Ready_queue_enqueue(
>> -      &node->Base.Base.Node.Chain,
>> -      &node->Ready_queue,
>> -      &self->Bit_map
>> -    );
>> -  } else {
>> -    _Scheduler_priority_Ready_queue_enqueue_first(
>> -      &node->Base.Base.Node.Chain,
>> -      &node->Ready_queue,
>> -      &self->Bit_map
>> -    );
>> +  filter_cpu = _Thread_Get_CPU( filter->user );
>> +  CPU = self->CPU;
>> +  cpu_max = _SMP_Get_processor_maximum();
>> +
>> +  for ( cpu_index = 0 ; cpu_index < cpu_max ; ++cpu_index ) {
>> +    CPU[ cpu_index ].visited = false;
>>    }
>> +
>> +  rear = rear + 1;
>> +  CPU[ rear ].cpu = filter_cpu;
>> +  CPU[ _Per_CPU_Get_index( filter_cpu ) ].visited = true;
>> +
>> +  highest_ready = _Scheduler_strong_APA_Find_highest_ready(
>> +                    self,
>> +                    front,
>> +                    rear
>> +                  );
>> +
>> +  if ( highest_ready != filter ) {
>> +    /*
>> +     * Backtrack on the path from
>> +     * filter_cpu to highest_ready, shifting along every task.
>> +     */
>> +
>> +    node = _Scheduler_strong_APA_Node_downcast( highest_ready );
>> +    /*
>> +     * Highest ready is not just directly reachable from the victim cpu
>> +     * So there is need of task shifting .
>> +     */
>> +    while( node->cpu_to_preempt !=  filter_cpu ){
>> +      curr_node = &node->Base.Base;
>> +      next_node = CPU[ _Per_CPU_Get_index( node->cpu_to_preempt )
>> ].executing;
>> +
>> +      _Scheduler_SMP_Preempt(
>> +        context,
>> +        curr_node,
>> +        next_node,
>> +        _Scheduler_strong_APA_Allocate_processor
>> +      );
>> +
>> +      if( curr_node == highest_ready) {
>> +        _Scheduler_strong_APA_Move_from_ready_to_scheduled(context,
>> curr_node);
>> +      }
>> +
>> +      node = _Scheduler_strong_APA_Node_downcast( next_node );
>> +    }
>> +    /*
>> +     * To save the last node so that the caller SMP_* function
>> +     * can do the allocation
>> +     */
>> +      curr_node = &node->Base.Base;
>> +      highest_ready = curr_node;
>> +    }
>> +
>> +  return highest_ready;
>>  }
>>
>> -static void _Scheduler_strong_APA_Extract_from_ready(
>> +/*
>> + * Checks the lowest scheduled directly reachable task
>> + */
>> +static inline Scheduler_Node *_Scheduler_strong_APA_Get_lowest_scheduled(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *the_thread
>> +  Scheduler_Node    *filter_base
>>  )
>>  {
>> -  Scheduler_strong_APA_Context *self =
>> -    _Scheduler_strong_APA_Get_self( context );
>> -  Scheduler_strong_APA_Node *node =
>> -    _Scheduler_strong_APA_Node_downcast( the_thread );
>> -
>> -  _Scheduler_priority_Ready_queue_extract(
>> -    &node->Base.Base.Node.Chain,
>> -    &node->Ready_queue,
>> -    &self->Bit_map
>> -  );
>> +  uint32_t                     cpu_max;
>> +  uint32_t                     cpu_index;
>> +  Scheduler_Node               *curr_node;
>> +  Scheduler_Node               *lowest_scheduled;
>> +  Priority_Control              max_priority_num;
>> +  Priority_Control              curr_priority;
>> +  Scheduler_strong_APA_Node    *filter_strong_node;
>> +  Scheduler_strong_APA_Context *self;
>> +
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  lowest_scheduled = NULL; // To remove compiler warning.
>> +  max_priority_num = 0;    // Max (Lowest) priority encountered so far.
>> +  filter_strong_node = _Scheduler_strong_APA_Node_downcast( filter_base
>> );
>> +
>> +  //lowest_scheduled is NULL if affinty of a node is 0
>> +  _Assert( !_Processor_mask_Zero( &filter_strong_node->Affinity ) );
>> +  cpu_max = _SMP_Get_processor_maximum();
>> +
>> +  for ( cpu_index = 0 ; cpu_index < cpu_max ; ++cpu_index ) {
>> +    //Checks if the CPU is in the affinity set of filter_strong_node
>> +    if ( _Processor_mask_Is_set( &filter_strong_node->Affinity,
>> cpu_index) ) {
>> +      Per_CPU_Control *cpu = _Per_CPU_Get_by_index( cpu_index );
>> +
>> +      if ( _Per_CPU_Is_processor_online( cpu ) ) {
>> +        curr_node = self->CPU[ _Per_CPU_Get_index( cpu ) ].executing;
>> +        curr_priority = _Scheduler_Node_get_priority( curr_node );
>> +        curr_priority = SCHEDULER_PRIORITY_PURIFY( curr_priority );
>> +
>> +        if ( curr_priority > max_priority_num ) {
>> +          lowest_scheduled = curr_node;
>> +          max_priority_num = curr_priority;
>> +        }
>> +      }
>> +    }
>> +  }
>> +
>> +  _Assert( lowest_scheduled != NULL );
>> +  return lowest_scheduled;
>>  }
>>
>> -static void _Scheduler_strong_APA_Do_update(
>> +static inline void _Scheduler_strong_APA_Extract_from_scheduled(
>>    Scheduler_Context *context,
>> -  Scheduler_Node *node_to_update,
>> -  Priority_Control new_priority
>> +  Scheduler_Node    *node_to_extract
>>  )
>>  {
>> -  Scheduler_strong_APA_Context *self =
>> -    _Scheduler_strong_APA_Get_self( context );
>> -  Scheduler_strong_APA_Node *node =
>> -    _Scheduler_strong_APA_Node_downcast( node_to_update );
>> -
>> -  _Scheduler_SMP_Node_update_priority( &node->Base, new_priority );
>> -  _Scheduler_priority_Ready_queue_update(
>> -    &node->Ready_queue,
>> -    SCHEDULER_PRIORITY_UNMAP( new_priority ),
>> -    &self->Bit_map,
>> -    &self->Ready[ 0 ]
>> -  );
>> +  Scheduler_strong_APA_Context *self;
>> +  Scheduler_strong_APA_Node    *node;
>> +
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  node = _Scheduler_strong_APA_Node_downcast( node_to_extract );
>> +
>> +  _Scheduler_SMP_Extract_from_scheduled( &self->Base.Base,
>> &node->Base.Base );
>> +  //Not removing it from Ready since the node could go in the READY
>> state.
>>  }
>>
>> -static Scheduler_strong_APA_Context *
>> -_Scheduler_strong_APA_Get_context( const Scheduler_Control *scheduler )
>> +static inline void _Scheduler_strong_APA_Extract_from_ready(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *node_to_extract
>> +)
>>  {
>> -  return (Scheduler_strong_APA_Context *) _Scheduler_Get_context(
>> scheduler );
>> +  Scheduler_strong_APA_Context *self;
>> +  Scheduler_strong_APA_Node    *node;
>> +
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  node = _Scheduler_strong_APA_Node_downcast( node_to_extract );
>> +
>> +  _Assert( !_Chain_Is_empty(self->Ready) );
>> +  _Assert( !_Chain_Is_node_off_chain( &node->Ready_node ) );
>> +
>> +   _Chain_Extract_unprotected( &node->Ready_node );    //Removed from
>> Ready
>> +   _Chain_Set_off_chain( &node->Ready_node );
>>  }
>>
>> -void _Scheduler_strong_APA_Initialize( const Scheduler_Control
>> *scheduler )
>> +static inline void _Scheduler_strong_APA_Insert_ready(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *node_base,
>> +  Priority_Control   insert_priority
>> +)
>>  {
>> -  Scheduler_strong_APA_Context *self =
>> -    _Scheduler_strong_APA_Get_context( scheduler );
>> +  Scheduler_strong_APA_Context *self;
>> +  Scheduler_strong_APA_Node    *node;
>>
>> -  _Scheduler_SMP_Initialize( &self->Base );
>> -  _Priority_bit_map_Initialize( &self->Bit_map );
>> -  _Scheduler_priority_Ready_queue_initialize(
>> -    &self->Ready[ 0 ],
>> -    scheduler->maximum_priority
>> -  );
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  node = _Scheduler_strong_APA_Node_downcast( node_base );
>> +
>> +  if( _Chain_Is_node_off_chain( &node->Ready_node ) ) {
>> +    _Chain_Append_unprotected( &self->Ready, &node->Ready_node );
>> +  }
>>  }
>>
>> -void _Scheduler_strong_APA_Node_initialize(
>> -  const Scheduler_Control *scheduler,
>> -  Scheduler_Node          *node,
>> -  Thread_Control          *the_thread,
>> -  Priority_Control         priority
>> +static inline void _Scheduler_strong_APA_Move_from_scheduled_to_ready(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *scheduled_to_ready
>>  )
>>  {
>> -  Scheduler_Context            *context;
>> -  Scheduler_strong_APA_Context *self;
>> -  Scheduler_strong_APA_Node    *the_node;
>> +  Priority_Control insert_priority;
>>
>> -  the_node = _Scheduler_strong_APA_Node_downcast( node );
>> -  _Scheduler_SMP_Node_initialize(
>> -    scheduler,
>> -    &the_node->Base,
>> -    the_thread,
>> -    priority
>> -  );
>> +  _Scheduler_SMP_Extract_from_scheduled( context, scheduled_to_ready );
>> +  insert_priority = _Scheduler_SMP_Node_priority( scheduled_to_ready );
>>
>> -  context = _Scheduler_Get_context( scheduler );
>> -  self = _Scheduler_strong_APA_Get_self( context );
>> -  _Scheduler_priority_Ready_queue_update(
>> -    &the_node->Ready_queue,
>> -    SCHEDULER_PRIORITY_UNMAP( priority ),
>> -    &self->Bit_map,
>> -    &self->Ready[ 0 ]
>> +  _Scheduler_strong_APA_Insert_ready(
>> +    context,
>> +    scheduled_to_ready,
>> +    insert_priority
>>    );
>>  }
>>
>> -static bool _Scheduler_strong_APA_Has_ready( Scheduler_Context *context )
>> +static inline Scheduler_Node* _Scheduler_strong_APA_Get_lowest_reachable(
>> +  Scheduler_strong_APA_Context *self,
>> +  uint32_t                      front,
>> +  uint32_t                      rear,
>> +  Per_CPU_Control             **cpu_to_preempt
>> +)
>>  {
>> -  Scheduler_strong_APA_Context *self =
>> -    _Scheduler_strong_APA_Get_self( context );
>> +  Scheduler_Node              *lowest_reachable;
>> +  Priority_Control             max_priority_num;
>> +  uint32_t                    cpu_max;
>> +  uint32_t                    cpu_index;
>> +  Thread_Control              *curr_thread;
>> +  Per_CPU_Control             *curr_CPU;
>> +  Priority_Control             curr_priority;
>> +  Scheduler_Node              *curr_node;
>> +  Scheduler_strong_APA_Node   *curr_strong_node; //Current
>> Strong_APA_Node
>> +  Scheduler_strong_APA_CPU    *CPU;
>> +
>> +  max_priority_num = 0; //Max (Lowest) priority encountered so far.
>> +  CPU = self->CPU;
>> +  cpu_max = _SMP_Get_processor_maximum();
>> +
>> +  while( front <= rear ) {
>> +    curr_CPU = CPU[ front ].cpu;
>> +    front = front + 1;
>> +
>> +    curr_node = CPU[ _Per_CPU_Get_index( curr_CPU ) ].executing;
>> +    curr_thread = curr_node->user;
>> +
>> +    curr_priority = _Scheduler_Node_get_priority( curr_node );
>> +    curr_priority = SCHEDULER_PRIORITY_PURIFY( curr_priority );
>> +
>> +    curr_strong_node = _Scheduler_strong_APA_Node_downcast( curr_node );
>> +
>> +    if ( curr_priority > max_priority_num ) {
>> +      lowest_reachable = curr_node;
>> +      max_priority_num = curr_priority;
>> +      *cpu_to_preempt = curr_CPU;
>> +    }
>> +
>> +    if ( !curr_thread->is_idle ) {
>> +      for ( cpu_index = 0 ; cpu_index < cpu_max ; ++cpu_index ) {
>> +        if ( _Processor_mask_Is_set( &curr_strong_node->Affinity,
>> cpu_index ) ) {
>> +          //Checks if the thread_CPU is in the affinity set of the node
>> +          Per_CPU_Control *cpu = _Per_CPU_Get_by_index( cpu_index );
>> +          if ( _Per_CPU_Is_processor_online( cpu ) && CPU[ cpu_index
>> ].visited == false ) {
>> +            rear = rear + 1;
>> +            CPU[ rear ].cpu = cpu;
>> +            CPU[ cpu_index ].visited = true;
>> +            CPU[ cpu_index ].preempting_node = curr_node;
>> +          }
>> +        }
>> +      }
>> +    }
>> +  }
>>
>> -  return !_Priority_bit_map_Is_empty( &self->Bit_map );
>> +  return lowest_reachable;
>>  }
>>
>> -static Scheduler_Node *_Scheduler_strong_APA_Get_highest_ready(
>> +static inline bool _Scheduler_strong_APA_Do_enqueue(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *node
>> +  Scheduler_Node    *lowest_reachable,
>> +  Scheduler_Node    *node,
>> +  Priority_Control  insert_priority,
>> +  Per_CPU_Control  *cpu_to_preempt
>>  )
>>  {
>> -  Scheduler_strong_APA_Context *self =
>> -    _Scheduler_strong_APA_Get_self( context );
>> +  bool                          needs_help;
>> +  Priority_Control              node_priority;
>> +  Priority_Control              lowest_priority;
>> +  Scheduler_strong_APA_CPU     *CPU;
>> +  Scheduler_Node               *curr_node;
>> +  Scheduler_strong_APA_Node    *curr_strong_node; //Current
>> Strong_APA_Node
>> +  Per_CPU_Control              *curr_CPU;
>> +  Scheduler_strong_APA_Context *self;
>> +  Scheduler_Node               *next_node;
>> +
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  CPU = self->CPU;
>> +
>> +  node_priority = _Scheduler_Node_get_priority( node );
>> +  node_priority = SCHEDULER_PRIORITY_PURIFY( node_priority );
>> +
>> +  lowest_priority =  _Scheduler_Node_get_priority( lowest_reachable );
>> +  lowest_priority = SCHEDULER_PRIORITY_PURIFY( lowest_priority );
>> +
>> +  if( lowest_priority > node_priority ) {
>> +    //Backtrack on the path from
>> +    //_Thread_Get_CPU(lowest_reachable->user) to lowest_reachable,
>> shifting
>> +    //along every task
>> +
>> +    curr_node = CPU[ _Per_CPU_Get_index(cpu_to_preempt)
>> ].preempting_node;
>> +    curr_strong_node = _Scheduler_strong_APA_Node_downcast( curr_node );
>> +    curr_strong_node->cpu_to_preempt = cpu_to_preempt;
>> +
>> +    //Save which cpu to preempt in cpu_to_preempt value of the node
>> +    while ( curr_node != node ) {
>> +      curr_CPU = _Thread_Get_CPU( curr_node->user );
>> +      curr_node = CPU[ _Per_CPU_Get_index( curr_CPU ) ].preempting_node;
>> +      curr_strong_node = _Scheduler_strong_APA_Node_downcast( curr_node
>> );
>> +      curr_strong_node->cpu_to_preempt =  curr_CPU;
>> +     }
>> +
>> +    curr_CPU = curr_strong_node->cpu_to_preempt;
>> +    next_node = CPU[ _Per_CPU_Get_index( curr_CPU ) ].executing;
>> +
>> +    node_priority = _Scheduler_Node_get_priority( curr_node );
>> +    node_priority = SCHEDULER_PRIORITY_PURIFY( node_priority );
>> +
>> +    _Scheduler_SMP_Enqueue_to_scheduled(
>> +      context,
>> +      curr_node,
>> +      node_priority,
>> +      next_node,
>> +      _Scheduler_SMP_Insert_scheduled,
>> +      _Scheduler_strong_APA_Move_from_scheduled_to_ready,
>> +      _Scheduler_strong_APA_Allocate_processor
>> +    );
>>
>> -  (void) node;
>> +    curr_node = next_node;
>> +    curr_strong_node = _Scheduler_strong_APA_Node_downcast( curr_node );
>>
>> -  return (Scheduler_Node *) _Scheduler_priority_Ready_queue_first(
>> -    &self->Bit_map,
>> -    &self->Ready[ 0 ]
>> -  );
>> +    while( curr_node !=  lowest_reachable ) {
>> +      curr_CPU = curr_strong_node->cpu_to_preempt;
>> +      next_node = CPU[ _Per_CPU_Get_index( curr_CPU ) ].executing;
>> +      //curr_node preempts the next_node;
>> +      _Scheduler_SMP_Preempt(
>> +       context,
>> +       curr_node,
>> +       next_node,
>> +       _Scheduler_strong_APA_Allocate_processor
>> +      );
>> +
>> +      curr_node = next_node;
>> +      curr_strong_node = _Scheduler_strong_APA_Node_downcast( curr_node
>> );
>> +    }
>> +
>> +    _Scheduler_strong_APA_Move_from_scheduled_to_ready( context,
>> lowest_reachable );
>> +
>> +    needs_help = false;
>> +  } else {
>> +    needs_help = true;
>> +  }
>> +
>> +  //Add it to Ready chain since it is now either scheduled or just ready.
>> +  _Scheduler_strong_APA_Insert_ready(context,node,insert_priority);
>> +
>> +  return needs_help;
>>  }
>>
>> -void _Scheduler_strong_APA_Block(
>> -  const Scheduler_Control *scheduler,
>> -  Thread_Control          *the_thread,
>> -  Scheduler_Node          *node
>> +/*
>> + * BFS Algorithm for task arrival
>> + * Enqueue node either in the scheduled chain or in the ready chain.
>> + * node is the newly arrived node and is currently not scheduled.
>> + */
>> +static inline bool _Scheduler_strong_APA_Enqueue(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *node,
>> +  Priority_Control   insert_priority
>>  )
>>  {
>> -  Scheduler_Context *context = _Scheduler_Get_context( scheduler );
>> +  Scheduler_strong_APA_Context *self;
>> +  Scheduler_strong_APA_CPU     *CPU;
>> +  uint32_t                     cpu_max;
>> +  uint32_t                     cpu_index;
>> +  Per_CPU_Control              *cpu_to_preempt;
>> +  Scheduler_Node               *lowest_reachable;
>> +  Scheduler_strong_APA_Node    *strong_node;
>>
>> -  _Scheduler_SMP_Block(
>> +  //Denotes front and rear of the queue
>> +  uint32_t     front;
>> +  uint32_t     rear;
>> +
>> +  front = 0;
>> +  rear = -1;
>> +
>> +  self = _Scheduler_strong_APA_Get_self( context );
>> +  strong_node = _Scheduler_strong_APA_Node_downcast( node );
>> +  cpu_max = _SMP_Get_processor_maximum();
>> +  CPU = self->CPU;
>> +
>> +  for ( cpu_index = 0 ; cpu_index < cpu_max ; ++cpu_index ) {
>> +    CPU[ cpu_index ].visited = false;
>> +
>> +    //Checks if the thread_CPU is in the affinity set of the node
>> +    if ( _Processor_mask_Is_set( &strong_node->Affinity, cpu_index) ) {
>> +      Per_CPU_Control *cpu = _Per_CPU_Get_by_index( cpu_index );
>> +
>> +      if ( _Per_CPU_Is_processor_online( cpu ) ) {
>> +        rear = rear + 1;
>> +        CPU[ rear ].cpu = cpu;
>> +        CPU[ cpu_index ].visited = true;
>> +        CPU[ cpu_index ].preempting_node = node;
>> +      }
>> +    }
>> +  }
>> +
>> +  //This assert makes sure that there always exist an element in the
>> +  // Queue when we start the queue traversal.
>> +  _Assert( !_Processor_mask_Zero( &strong_node->Affinity ) );
>> +
>> +  lowest_reachable = _Scheduler_strong_APA_Get_lowest_reachable(
>> +                       self,
>> +                       front,
>> +                       rear,
>> +                       &cpu_to_preempt
>> +                     );
>> +
>> +  return _Scheduler_strong_APA_Do_enqueue(
>> +           context,
>> +           lowest_reachable,
>> +           node,
>> +           insert_priority,
>> +           cpu_to_preempt
>> +         );
>> +}
>> +
>> +static inline bool _Scheduler_strong_APA_Enqueue_scheduled(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *node,
>> +  Priority_Control   insert_priority
>> +)
>> +{
>> +  return _Scheduler_SMP_Enqueue_scheduled(
>>      context,
>> -    the_thread,
>>      node,
>> -    _Scheduler_SMP_Extract_from_scheduled,
>> +    insert_priority,
>> +    _Scheduler_SMP_Priority_less_equal,
>>      _Scheduler_strong_APA_Extract_from_ready,
>>      _Scheduler_strong_APA_Get_highest_ready,
>> +    _Scheduler_strong_APA_Insert_ready,
>> +    _Scheduler_SMP_Insert_scheduled,
>>      _Scheduler_strong_APA_Move_from_ready_to_scheduled,
>> -    _Scheduler_SMP_Allocate_processor_exact
>> +    _Scheduler_strong_APA_Allocate_processor
>>    );
>>  }
>>
>> -static bool _Scheduler_strong_APA_Enqueue(
>> +static inline bool _Scheduler_strong_APA_Do_ask_for_help(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *node,
>> -  Priority_Control   insert_priority
>> +  Thread_Control    *the_thread,
>> +  Scheduler_Node    *node
>>  )
>>  {
>> -  return _Scheduler_SMP_Enqueue(
>> +  return _Scheduler_SMP_Ask_for_help(
>>      context,
>> +    the_thread,
>>      node,
>> -    insert_priority,
>>      _Scheduler_SMP_Priority_less_equal,
>>      _Scheduler_strong_APA_Insert_ready,
>>      _Scheduler_SMP_Insert_scheduled,
>>      _Scheduler_strong_APA_Move_from_scheduled_to_ready,
>> -    _Scheduler_SMP_Get_lowest_scheduled,
>> -    _Scheduler_SMP_Allocate_processor_exact
>> +    _Scheduler_strong_APA_Get_lowest_scheduled,
>> +    _Scheduler_strong_APA_Allocate_processor
>>    );
>>  }
>>
>> -static bool _Scheduler_strong_APA_Enqueue_scheduled(
>> +static inline void _Scheduler_strong_APA_Register_idle(
>>    Scheduler_Context *context,
>> -  Scheduler_Node    *node,
>> -  Priority_Control  insert_priority
>> +  Scheduler_Node    *idle_base,
>> +  Per_CPU_Control   *cpu
>>  )
>>  {
>> -  return _Scheduler_SMP_Enqueue_scheduled(
>> +  (void) context;
>> +  (void) idle_base;
>> +  (void) cpu;
>> +  /*
>> +   * We do not maintain a variable to access the scheduled
>> +   * node for a CPU. So this function does nothing.
>> +   */
>> +}
>> +
>> +static inline  void  _Scheduler_strong_APA_Do_set_affinity(
>> +  Scheduler_Context *context,
>> +  Scheduler_Node    *node_base,
>> +  void              *arg
>> +)
>> +{
>> +  Scheduler_strong_APA_Node *node;
>> +
>> +  node = _Scheduler_strong_APA_Node_downcast( node_base );
>> +  node->Affinity = *(( const Processor_mask *) arg);
>> +}
>> +
>> +void _Scheduler_strong_APA_Initialize( const Scheduler_Control
>> *scheduler )
>> +{
>> +  Scheduler_strong_APA_Context *self =
>> +      _Scheduler_strong_APA_Get_context( scheduler );
>> +
>> +  _Scheduler_SMP_Initialize( &self->Base );
>> +  _Chain_Initialize_empty( &self->Ready );
>> +}
>> +
>> +void _Scheduler_strong_APA_Yield(
>> +  const Scheduler_Control *scheduler,
>> +  Thread_Control          *thread,
>> +  Scheduler_Node          *node
>> +)
>> +{
>> +  Scheduler_Context *context = _Scheduler_Get_context( scheduler );
>> +
>> +  _Scheduler_SMP_Yield(
>>      context,
>> +    thread,
>>      node,
>> -    insert_priority,
>> -    _Scheduler_SMP_Priority_less_equal,
>>      _Scheduler_strong_APA_Extract_from_ready,
>> -    _Scheduler_strong_APA_Get_highest_ready,
>> -    _Scheduler_strong_APA_Insert_ready,
>> -    _Scheduler_SMP_Insert_scheduled,
>> -    _Scheduler_strong_APA_Move_from_ready_to_scheduled,
>> -    _Scheduler_SMP_Allocate_processor_exact
>> +    _Scheduler_strong_APA_Enqueue,
>> +    _Scheduler_strong_APA_Enqueue_scheduled
>>    );
>>  }
>>
>> -void _Scheduler_strong_APA_Unblock(
>> +void _Scheduler_strong_APA_Block(
>>    const Scheduler_Control *scheduler,
>> -  Thread_Control          *the_thread,
>> +  Thread_Control          *thread,
>>    Scheduler_Node          *node
>>  )
>>  {
>>    Scheduler_Context *context = _Scheduler_Get_context( scheduler );
>> -
>> -  _Scheduler_SMP_Unblock(
>> +  //The extract from ready automatically removes the node from Ready
>> chain.
>> +  _Scheduler_SMP_Block(
>>      context,
>> -    the_thread,
>> +    thread,
>>      node,
>> -    _Scheduler_strong_APA_Do_update,
>> -    _Scheduler_strong_APA_Enqueue
>> +    _Scheduler_strong_APA_Extract_from_scheduled,
>> +    _Scheduler_strong_APA_Extract_from_ready,
>> +    _Scheduler_strong_APA_Get_highest_ready,
>> +    _Scheduler_strong_APA_Move_from_ready_to_scheduled,
>> +    _Scheduler_strong_APA_Allocate_processor
>>    );
>>  }
>>
>> -static bool _Scheduler_strong_APA_Do_ask_for_help(
>> -  Scheduler_Context *context,
>> -  Thread_Control    *the_thread,
>> -  Scheduler_Node    *node
>> +void _Scheduler_strong_APA_Unblock(
>> +  const Scheduler_Control *scheduler,
>> +  Thread_Control          *thread,
>> +  Scheduler_Node          *node
>>  )
>>  {
>> -  return _Scheduler_SMP_Ask_for_help(
>> +  Scheduler_Context *context = _Scheduler_Get_context( scheduler );
>> +
>> +  _Scheduler_SMP_Unblock(
>>      context,
>> -    the_thread,
>> +    thread,
>>      node,
>> -    _Scheduler_SMP_Priority_less_equal,
>> -    _Scheduler_strong_APA_Insert_ready,
>> -    _Scheduler_SMP_Insert_scheduled,
>> -    _Scheduler_strong_APA_Move_from_scheduled_to_ready,
>> -    _Scheduler_SMP_Get_lowest_scheduled,
>> -    _Scheduler_SMP_Allocate_processor_lazy
>> +    _Scheduler_strong_APA_Do_update,
>> +    _Scheduler_strong_APA_Enqueue
>>    );
>>  }
>>
>>  void _Scheduler_strong_APA_Update_priority(
>>    const Scheduler_Control *scheduler,
>> -  Thread_Control          *the_thread,
>> +  Thread_Control          *thread,
>>    Scheduler_Node          *node
>>  )
>>  {
>> @@ -327,7 +793,7 @@ void _Scheduler_strong_APA_Update_priority(
>>
>>    _Scheduler_SMP_Update_priority(
>>      context,
>> -    the_thread,
>> +    thread,
>>      node,
>>      _Scheduler_strong_APA_Extract_from_ready,
>>      _Scheduler_strong_APA_Do_update,
>> @@ -345,7 +811,11 @@ bool _Scheduler_strong_APA_Ask_for_help(
>>  {
>>    Scheduler_Context *context = _Scheduler_Get_context( scheduler );
>>
>> -  return _Scheduler_strong_APA_Do_ask_for_help( context, the_thread,
>> node );
>> +  return _Scheduler_strong_APA_Do_ask_for_help(
>> +    context,
>> +    the_thread,
>> +    node
>> +  );
>>  }
>>
>>  void _Scheduler_strong_APA_Reconsider_help_request(
>> @@ -381,7 +851,7 @@ void _Scheduler_strong_APA_Withdraw_node(
>>      _Scheduler_strong_APA_Extract_from_ready,
>>      _Scheduler_strong_APA_Get_highest_ready,
>>      _Scheduler_strong_APA_Move_from_ready_to_scheduled,
>> -    _Scheduler_SMP_Allocate_processor_lazy
>> +    _Scheduler_strong_APA_Allocate_processor
>>    );
>>  }
>>
>> @@ -416,20 +886,65 @@ Thread_Control
>> *_Scheduler_strong_APA_Remove_processor(
>>    );
>>  }
>>
>> -void _Scheduler_strong_APA_Yield(
>> +void _Scheduler_strong_APA_Node_initialize(
>>    const Scheduler_Control *scheduler,
>> +  Scheduler_Node          *node,
>>    Thread_Control          *the_thread,
>> -  Scheduler_Node          *node
>> +  Priority_Control         priority
>>  )
>>  {
>> -  Scheduler_Context *context = _Scheduler_Get_context( scheduler );
>> +  Scheduler_SMP_Node *smp_node;
>> +  Scheduler_strong_APA_Node *strong_node;
>>
>> -  _Scheduler_SMP_Yield(
>> -    context,
>> -    the_thread,
>> -    node,
>> -    _Scheduler_strong_APA_Extract_from_ready,
>> -    _Scheduler_strong_APA_Enqueue,
>> -    _Scheduler_strong_APA_Enqueue_scheduled
>> +  smp_node = _Scheduler_SMP_Node_downcast( node );
>> +  strong_node = _Scheduler_strong_APA_Node_downcast( node );
>> +
>> +  _Scheduler_SMP_Node_initialize( scheduler, smp_node, the_thread,
>> priority );
>> +
>> +  _Processor_mask_Assign(
>> +    &strong_node->Affinity,
>> +   _SMP_Get_online_processors()
>>    );
>>  }
>> +
>> +bool _Scheduler_strong_APA_Set_affinity(
>> +  const Scheduler_Control *scheduler,
>> +  Thread_Control          *thread,
>> +  Scheduler_Node          *node_base,
>> +  const Processor_mask    *affinity
>> +)
>> +{
>> +  Scheduler_Context         *context;
>> +  Scheduler_strong_APA_Node *node;
>> +  Processor_mask             local_affinity;
>> +
>> +  context = _Scheduler_Get_context( scheduler );
>> +  _Processor_mask_And( &local_affinity, &context->Processors, affinity );
>> +
>> +  if ( _Processor_mask_Is_zero( &local_affinity ) ) {
>> +    return false;
>> +  }
>> +
>> +  node = _Scheduler_strong_APA_Node_downcast( node_base );
>> +
>> +  if ( _Processor_mask_Is_equal( &node->Affinity, affinity ) )
>> +    return true;       //Nothing to do. Return true.
>> +
>> + _Processor_mask_Assign( &node->Affinity, &local_affinity );
>> +
>> + _Scheduler_SMP_Set_affinity(
>> +   context,
>> +   thread,
>> +   node_base,
>> +   &local_affinity,
>> +   _Scheduler_strong_APA_Do_set_affinity,
>> +   _Scheduler_strong_APA_Extract_from_ready,
>> +   _Scheduler_strong_APA_Get_highest_ready,
>> +   _Scheduler_strong_APA_Move_from_ready_to_scheduled,
>> +   _Scheduler_strong_APA_Enqueue,
>> +   _Scheduler_strong_APA_Allocate_processor
>> + );
>> +
>> +  return true;
>> +}
>> +
>> --
>> 2.17.1
>>
>>
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