Scheduler Handler

This group contains the Scheduler Handler implementation. More...

Topics
	Constant Bandwidth Server (CBS) Scheduler
	This group contains the Constant Bandwidth Server (CBS) Scheduler implementation.
	Deterministic Priority Scheduler
	This group contains the Deterministic Priority Scheduler implementation.
	EDF Scheduler
	This group contains the EDF Scheduler implementation.
	SMP Scheduler
	This group contains the SMP Scheduler implementation.
	Simple Priority Scheduler
	This group contains the Simple Priority Scheduler implementation.

Files
file	cpukit/include/rtems/score/scheduler.h
	This header file provides interfaces of the Scheduler Handler which are used by the implementation and the Application Configuration.
file	cpukit/include/rtems/score/schedulerimpl.h
	This header file provides interfaces of the Scheduler Handler which are only used by the implementation.
file	cpukit/include/rtems/score/schedulernode.h
	This header file provides interfaces of the Scheduler Handler related to scheduler nodes which are used by the implementation and the Application Configuration.
file	cpukit/include/rtems/score/schedulernodeimpl.h
	This header file provides interfaces of the Scheduler Handler related to scheduler nodes which are only used by the implementation.
file	cpukit/include/rtems/score/scheduleruniimpl.h
	This header file provides interfaces of the supporting the implementation of uniprocessor schedulers.
file	cpukit/score/src/sched.c
	This source file contains the implementation of _Sched_Count(), _Sched_Index(), _Sched_Name_to_index(), and _Sched_Processor_count().
file	cpukit/score/src/scheduler.c
	This source file contains the implementation of _Scheduler_Handler_initialization().
file	cpukit/score/src/schedulerdefaultmakecleansticky.c
	This source file contains the implementation of _Scheduler_default_Sticky_do_nothing().
file	cpukit/score/src/schedulerdefaultmappriority.c
	This source file contains the implementation of _Scheduler_default_Map_priority() and _Scheduler_default_Unmap_priority().
file	cpukit/score/src/schedulerdefaultnodedestroy.c
	This source file contains the implementation of _Scheduler_default_Node_destroy().
file	cpukit/score/src/schedulerdefaultnodeinit.c
	This source file contains the implementation of _Scheduler_default_Node_initialize().
file	cpukit/score/src/schedulerdefaultpinunpin.c
	This source file contains the implementation of _Scheduler_default_Pin_or_unpin_not_supported().
file	cpukit/score/src/schedulerdefaultpinunpindonothing.c
	This source file contains the implementation of _Scheduler_default_Pin_or_unpin_do_nothing().
file	cpukit/score/src/schedulerdefaultreleasejob.c
	This source file contains the implementation of _Scheduler_default_Release_job() and _Scheduler_default_Cancel_job().
file	cpukit/score/src/schedulerdefaultschedule.c
	This source file contains the implementation of _Scheduler_default_Schedule().
file	cpukit/score/src/schedulerdefaultsetaffinity.c
	This source file contains the implementation of _Scheduler_default_Set_affinity().
file	cpukit/score/src/schedulerdefaultstartidle.c
	This source file contains the implementation of _Scheduler_default_Start_idle().
file	cpukit/score/src/schedulergetaffinity.c
	This source file contains the implementation of _Scheduler_Get_affinity().
file	cpukit/score/src/schedulersetaffinity.c
	This source file contains the implementation of _Scheduler_Set_affinity().
file	cpukit/score/src/schedulersmp.c
	This source file contains the implementation of _Scheduler_Request_ask_for_help().
file	cpukit/score/src/schedulersmpstartidle.c
	This source file contains the implementation of _Scheduler_SMP_Start_idle().

Data Structures
struct	Scheduler_Operations
	The scheduler operations. More...
struct	Scheduler_Context
	Scheduler context. More...
struct	_Scheduler_Control
	Scheduler control. More...
struct	Scheduler_Node
	Scheduler node for per-thread data. More...
struct	Scheduler_Node::[struct].Wait
	Thread wait support block. More...
struct	Scheduler_Node::[struct].Priority
	The thread priority information used by the scheduler. More...

Macros
#define	_Scheduler_Count   ( (size_t) 1 )
	This constant contains the count of configured schedulers.
#define	SCHEDULER_DEFAULT_SMP_OPERATIONS
	This define provides a set of default implementations for SMP-specific scheduler operations.
#define	SCHEDULER_DEFAULT_SET_AFFINITY_OPERATION
	This define provides the default implementation for the SMP-specific set affinity operation.
#define	PRIORITY_MAXIMUM   ( _Scheduler_Table[ 0 ].maximum_priority )
	This defines the lowest (least important) thread priority of the first scheduler instance.
#define	SCHEDULER_NODE_OF_WAIT_PRIORITY_NODE(node)
#define	SCHEDULER_NODE_OF_WAIT_PRIORITY(node)
#define	SCHEDULER_PRIORITY_MAP(priority)
	Maps a priority value to support the append indicator.
#define	SCHEDULER_PRIORITY_UNMAP(priority)
	Returns the plain priority value.
#define	SCHEDULER_PRIORITY_PURIFY(priority)
	Clears the priority append indicator bit.
#define	SCHEDULER_PRIORITY_APPEND(priority)
	Returns the priority control with the append indicator bit set.
#define	SCHEDULER_PRIORITY_IS_APPEND(priority)
	Returns true, if the item should be appended to its priority group, otherwise returns false and the item should be prepended to its priority group.

Typedefs
typedef struct _Scheduler_Control	Scheduler_Control
typedef struct Scheduler_Context	Scheduler_Context
	Scheduler context.
typedef struct Scheduler_Node	Scheduler_Node

Functions
Priority_Control	_Scheduler_default_Map_priority (const Scheduler_Control *scheduler, Priority_Control priority)
	Returns the scheduler internal thread priority mapped by SCHEDULER_PRIORITY_MAP().
Priority_Control	_Scheduler_default_Unmap_priority (const Scheduler_Control *scheduler, Priority_Control priority)
	Returns the user visible thread priority unmapped by SCHEDULER_PRIORITY_UNMAP().
void	_Scheduler_default_Schedule (const Scheduler_Control *scheduler, Thread_Control *the_thread)
	Does nothing.
void	_Scheduler_default_Node_initialize (const Scheduler_Control *scheduler, Scheduler_Node *node, Thread_Control *the_thread, Priority_Control priority)
	Performs the scheduler base node initialization.
void	_Scheduler_default_Node_destroy (const Scheduler_Control *scheduler, Scheduler_Node *node)
	Does nothing.
void	_Scheduler_default_Release_job (const Scheduler_Control *scheduler, Thread_Control *the_thread, Priority_Node *priority_node, uint64_t deadline, Thread_queue_Context *queue_context)
	Does nothing.
void	_Scheduler_default_Cancel_job (const Scheduler_Control *scheduler, Thread_Control *the_thread, Priority_Node *priority_node, Thread_queue_Context *queue_context)
	Does nothing.
void	_Scheduler_default_Start_idle (const Scheduler_Control *scheduler, Thread_Control *the_thread, struct Per_CPU_Control *cpu)
	Starts an idle thread.
void	_Scheduler_Handler_initialization (void)
	Initializes the scheduler to the policy chosen by the user.
Status_Control	_Scheduler_Get_affinity (Thread_Control *the_thread, size_t cpusetsize, cpu_set_t *cpuset)
	Copies the thread's scheduler's affinity to the given cpuset.
Status_Control	_Scheduler_Set_affinity (Thread_Control *the_thread, size_t cpusetsize, const cpu_set_t *cpuset)
	Sets the thread's scheduler's affinity.

Variables
const Scheduler_Control	_Scheduler_Table []
	This table contains the configured schedulers.

Detailed Description

This group contains the Scheduler Handler implementation.

This handler encapsulates functionality related to managing sets of threads that are ready for execution.

Schedulers are used by the system to manage sets of threads that are ready for execution. A scheduler consists of

• a scheduler algorithm implementation,
• a scheduler index and an associated name, and
• a set of processors owned by the scheduler (may be empty, but never overlaps with a set owned by another scheduler).

Each thread uses exactly one scheduler as its home scheduler. Threads may temporarily use another scheduler due to actions of locking protocols.

All properties of a scheduler can be configured and controlled by the user. Some properties are fixed at link time (defined by application configuration options), other properties can be changed at runtime through directive calls.

The scheduler index, name, and initial processor set are defined for a particular application by the application configuration. The schedulers are registered in the _Scheduler_Table which has _Scheduler_Count entries.

Macro Definition Documentation

_Scheduler_Count

#define _Scheduler_Count   ( (size_t) 1 )

This constant contains the count of configured schedulers.

In SMP configurations, the constant is defined by <rtems/confdefs.h> through the count of entries of the CONFIGURE_SCHEDULER_TABLE_ENTRIES application configuration option.

In uniprocessor configurations, this is a compile time constant set to one. This is important so that the compiler can optimize some loops away.

See also

_Scheduler_Table.

SCHEDULER_DEFAULT_SET_AFFINITY_OPERATION

#define SCHEDULER_DEFAULT_SET_AFFINITY_OPERATION

This define provides the default implementation for the SMP-specific set affinity operation.

The default implementation _Scheduler_default_Set_affinity() is intended for uniprocessor schedulers and SMP schedulers which only support an affinity to all online processors.

If SMP support is disabled, the define evaluates to nothing.

SCHEDULER_DEFAULT_SMP_OPERATIONS

#define SCHEDULER_DEFAULT_SMP_OPERATIONS

This define provides a set of default implementations for SMP-specific scheduler operations.

The default implementations are intended for uniprocessor schedulers. SMP schedulers shall implement the operations properly.

If SMP support is disabled, the define evaluates to nothing.

If SMP support is enabled and the system has exactly one processor, then it may use an uniprocessor scheduler. The ask for help, reconsider help request, and withdraw node operations are NULL, since they are only used if a thread has at least one helping scheduler node. At least two schedulers are required to get a helping node and each scheduler involved must own at least one processor. This is not possible on a system with exactly one processor. The processor add operation is NULL, since there is no other processor to add. The processor remove operation is NULL, since the one and only processor cannot be removed.

SCHEDULER_NODE_OF_WAIT_PRIORITY

#define SCHEDULER_NODE_OF_WAIT_PRIORITY

(

node

)

Value:

RTEMS_CONTAINER_OF( node, Scheduler_Node, Wait.Priority )

SCHEDULER_NODE_OF_WAIT_PRIORITY_NODE

#define SCHEDULER_NODE_OF_WAIT_PRIORITY_NODE

(

node

)

Value:

RTEMS_CONTAINER_OF( node, Scheduler_Node, Wait.Priority.Node.Node.Chain )

SCHEDULER_PRIORITY_APPEND

#define SCHEDULER_PRIORITY_APPEND

(

priority

)

Value:

( ( priority ) | ( (Priority_Control) PRIORITY_GROUP_LAST ) )

Returns the priority control with the append indicator bit set.

SCHEDULER_PRIORITY_IS_APPEND

#define SCHEDULER_PRIORITY_IS_APPEND

(

priority

)

Value:

( ( ( priority ) & ( (Priority_Control) PRIORITY_GROUP_LAST ) ) != 0 )

Returns true, if the item should be appended to its priority group, otherwise returns false and the item should be prepended to its priority group.

SCHEDULER_PRIORITY_MAP

#define SCHEDULER_PRIORITY_MAP

(

priority

)

Value:

( ( priority ) << 1 )

Maps a priority value to support the append indicator.

SCHEDULER_PRIORITY_PURIFY

#define SCHEDULER_PRIORITY_PURIFY

(

priority

)

Value:

( ( priority ) & ~( (Priority_Control) PRIORITY_GROUP_LAST ) )

Clears the priority append indicator bit.

SCHEDULER_PRIORITY_UNMAP

#define SCHEDULER_PRIORITY_UNMAP

(

priority

)

Value:

( ( priority ) >> 1 )

Returns the plain priority value.

Typedef Documentation

Scheduler_Context

typedef struct Scheduler_Context Scheduler_Context

Scheduler context.

The scheduler context of a particular scheduler implementation must place this structure at the begin of its context structure.

Function Documentation

_Scheduler_default_Cancel_job()

void _Scheduler_default_Cancel_job	(	const Scheduler_Control *	scheduler,
		Thread_Control *	the_thread,
		Priority_Node *	priority_node,
		Thread_queue_Context *	queue_context )

Does nothing.

Parameters

scheduler	This parameter is unused.
the_thread	This parameter is unused.
priority_node	This parameter is unused.
queue_context	This parameter is unused.

Returns

Always returns NULL.

_Scheduler_default_Map_priority()

Priority_Control _Scheduler_default_Map_priority	(	const Scheduler_Control *	scheduler,
		Priority_Control	priority )

Returns the scheduler internal thread priority mapped by SCHEDULER_PRIORITY_MAP().

Parameters

scheduler	Unused.
priority	The user visible thread priority.

Returns

The scheduler internal thread priority.

_Scheduler_default_Node_destroy()

void _Scheduler_default_Node_destroy	(	const Scheduler_Control *	scheduler,
		Scheduler_Node *	node )

Does nothing.

Parameters

scheduler	This parameter is unused.
node	This parameter is unused.

_Scheduler_default_Node_initialize()

void _Scheduler_default_Node_initialize	(	const Scheduler_Control *	scheduler,
		Scheduler_Node *	node,
		Thread_Control *	the_thread,
		Priority_Control	priority )

Performs the scheduler base node initialization.

Parameters

	scheduler	This parameter is unused.
[out]	node	The node to initialize.
	the_thread	This parameter is unused.
	priority	The thread priority.

_Scheduler_default_Release_job()

void _Scheduler_default_Release_job	(	const Scheduler_Control *	scheduler,
		Thread_Control *	the_thread,
		Priority_Node *	priority_node,
		uint64_t	deadline,
		Thread_queue_Context *	queue_context )

Does nothing.

Parameters

scheduler	This parameter is unused.
the_thread	This parameter is unused.
priority_node	This parameter is unused.
deadline	This parameter is unused.
queue_context	This parameter is unused.

Returns

Always returns NULL.

_Scheduler_default_Schedule()

void _Scheduler_default_Schedule	(	const Scheduler_Control *	scheduler,
		Thread_Control *	the_thread )

Does nothing.

Parameters

scheduler	This parameter is unused.
the_thread	This parameter is unused.

_Scheduler_default_Start_idle()

void _Scheduler_default_Start_idle	(	const Scheduler_Control *	scheduler,
		Thread_Control *	the_thread,
		struct Per_CPU_Control *	cpu )

Starts an idle thread.

Parameters

	scheduler	This parameter is unused.
[in,out]	the_thread	An idle thread.
	cpu	This parameter is unused.

_Scheduler_default_Unmap_priority()

Priority_Control _Scheduler_default_Unmap_priority	(	const Scheduler_Control *	scheduler,
		Priority_Control	priority )

Returns the user visible thread priority unmapped by SCHEDULER_PRIORITY_UNMAP().

Parameters

scheduler	Unused.
priority	The scheduler internal thread priority.

Returns

priority The user visible thread priority.

_Scheduler_Get_affinity()

Status_Control _Scheduler_Get_affinity	(	Thread_Control *	the_thread,
		size_t	cpusetsize,
		cpu_set_t *	cpuset )

Copies the thread's scheduler's affinity to the given cpuset.

Parameters

	the_thread	The thread to get the affinity of its scheduler.
	cpusetsize	The size of cpuset.
[out]	cpuset	The cpuset that serves as destination for the copy operation

Return values

STATUS_SUCCESSFUL	The operation succeeded.
STATUS_INVALID_SIZE	The processor set was too small.

_Scheduler_Handler_initialization()

void _Scheduler_Handler_initialization

(

void

)

Initializes the scheduler to the policy chosen by the user.

This routine initializes the scheduler to the policy chosen by the user through confdefs, or to the priority scheduler with ready chains by default.

_Scheduler_Set_affinity()

Status_Control _Scheduler_Set_affinity	(	Thread_Control *	the_thread,
		size_t	cpusetsize,
		const cpu_set_t *	cpuset )

Sets the thread's scheduler's affinity.

Parameters

[in,out]	the_thread	The thread to set the affinity of.
	cpusetsize	The size of cpuset.
	cpuset	The cpuset to set the affinity.

Return values

STATUS_SUCCESSFUL	The operation succeeded.
STATUS_INVALID_NUMBER	The processor set was not a valid new processor affinity set for the thread.

Variable Documentation

_Scheduler_Table

const Scheduler_Control _Scheduler_Table[]

extern

This table contains the configured schedulers.

The table is defined by <rtems/confdefs.h> through the CONFIGURE_SCHEDULER_TABLE_ENTRIES application configuration option.

See also

_Scheduler_Count.