Defines Scheduling structure. This struct is used to manages the scheduling informations relative to each task. More...

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Classes
struct	Scheduling
	This structure stores variables useful to manage the task scheduling (for BE or RT) Some of the values are only used for RT tasks. More...

Macros
#define	FREE -1
	Scheduling position not have a valid task.

#define	READY 0
	Task is in ready to execute.

#define	WAITING 1
	Task is waiting for a message.

#define	RUNNING 2
	Task is running in the CPU.

#define	MIGRATING 3
	Task is being migrated.

#define	BLOCKED 4
	Task is blocked waiting for the manager send a TASK_RELEASE packet.

#define	SLEEPING 5
	Task already executed all its execution time and is sleeping until the end of period.

#define	DEBUG 0
	When enabled shows the puts placed within local_scheduler.c.

#define	NO_DEADLINE -1
	A task that is best-effor have its deadline variable equal to -1.

#define	MAX_TIME_SLICE 16318
	Standard time slice value for task execution.

Functions
void	real_time_task (Scheduling *, unsigned int, int, unsigned int)

unsigned int	get_time_slice ()

void	init_scheduling_ptr (Scheduling **, int)

void	clear_scheduling (Scheduling *)

Scheduling *	LST (unsigned int)

Detailed Description

Defines Scheduling structure. This struct is used to manages the scheduling informations relative to each task.

HEMPS VERSION - 8.0 - support for RT applications

Distribution: June 2016

A given task can be BE (Best-Effort) or RT (Real-Time).

BE task have not timing constraints. RT have the timing constraints defined according the next diagram

Periodic task real-time parameters

|<---------— period --------------—> | | |

<---------—deadline---------—>

_______________________

|| execution time |<-slack->| | ||_______________________|_________|_____| ^ time -> | | ready time

Function Documentation

void clear_scheduling ( Scheduling * scheduling_tcb )

Clear a scheduling instance, used when the task is removed from slave processor

Parameters

scheduling_tcb Scheduling pointer to be cleared

unsigned int get_time_slice ( )

Get the time slice. Useful to provide the kernel slave time slice

Initializes the scheduling array with valid pointers

Parameters

sched_ptr	Pointer to pointer of the scheduler variable into TCB structure
tcb_index	TCB array index

Scheduling* LST ( unsigned int current_time )

The LST algorithm called by kernel slave. It select the next RT task with the least slack time, or the next BE task following a round-robin order

Parameters

current_time Current system time

Funcion called by kernel slave when a task call the primitive RealTime. This function set the real-time paramenters for the task.

Parameters

real_time_task	Task pointer that change or is setting its RT parameters
period	Task period in clock cycles
deadline	Task deadline in clock cycles
execution_time	Task execution time in clock cycles