rt_monotonic_sched.c

实时操作系统RT LINUX的源代码

/* A simple rate-monotonic scheduler */
#ifndef MODULE
#   define MODULE
#endif

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/version.h>
#include <linux/errno.h>
#include <linux/malloc.h>

#include <linux/kernel.h>
#include <linux/cons.h>

#ifdef MODVERSIONS
#   include <linux/modversions.h>
#endif

#include <asm/system.h>
#include <asm/rt_time.h>
#include <asm/rt_irq.h>
#include <asm/segment.h>

#include "rt_sched.h"
#include <linux/rtf.h>


#ifdef DEBUG

/* Process's state ( for debug purposes only ) */ 
#include "control.h"
RTIME init_time = 0;

#endif

#define __STR(x) #x
#define STR(x) __STR(x)

#define PRINTAX \
	"pushl %%eax\n\t" \
	"pushl %%ebp\n\t" \
	"pushl %%edi\n\t" \
	"pushl %%esi\n\t" \
	"pushl %%edx\n\t" \
	"pushl %%ecx\n\t" \
	"pushl %%ebx\n\t" \
	"pushl %%eax\n\t" \
	"call "SYMBOL_NAME_STR(conprn)"\n\t" \
	"add $4, %%esp\n\t" \
	"popl %%ebx\n\t \
	popl %%ecx\n\t \
	popl %%edx\n\t \
	popl %%esi\n\t \
	popl %%edi\n\t \
	popl %%ebp\n\t \
	popl %%eax\n\t"

#define rt_switch_to(tsk) \
	__asm__ __volatile__( \
	"pushl %%eax\n\t" \
	"pushl %%ebp\n\t" \
	"pushl %%edi\n\t" \
	"pushl %%esi\n\t" \
	"pushl %%edx\n\t" \
	"pushl %%ecx\n\t" \
	"pushl %%ebx\n\t" \
	"movl "SYMBOL_NAME_STR(rt_current)", %%edx\n\t" \
	"cmpl $0, 4(%%edx)\n\t" \
	"jz 25f\n\t" \
	"sub $108,%%esp\n\t" \
	"fsave (%%esp)\n\t" \
"25:	pushl $1f\n\t" \
	"movl %%esp, (%%edx)\n\t" \
	"movl (%%ecx), %%esp\n\t" \
	"movl %%ecx, "SYMBOL_NAME_STR(rt_current)"\n\t" \
	"ret\n\t" \
"1:	cmpl $0, 4(%%ecx)\n\t" \
	"jz 26f\n\t" \
	"frstor (%%esp)\n\t" \
	"add $108,%%esp \n\t" \
"26:	popl %%ebx\n\t" \
	"popl %%ecx\n\t" \
	"popl %%edx\n\t" \
	"popl %%esi\n\t" \
	"popl %%edi\n\t" \
	"popl %%ebp\n\t" \
	"popl %%eax\n\t" \
	: /* no output */ \
	: "c" (tsk) \
	:"cx");

/* RT_TASK *run_queue; */
RT_TASK *rt_tasks;

RT_TASK *rt_current;

RT_TASK rt_linux_task;
static int linux_irq_state;

extern int rt_startup(void);
__asm__(".align 4; .globl "SYMBOL_NAME_STR(rt_startup)"\n\t"
		SYMBOL_NAME_STR(rt_startup)": iret");

int rt_task_init(RT_TASK *task, void (*fn)(int), int data, int stack_size, 
		 int id) /* Monotonic */ 
{
	int *st;
	long flags;

	if (task->magic == RT_TASK_MAGIC) { 
		return -EINVAL;
	}

	st = (int *) kmalloc(stack_size, GFP_KERNEL);	
	if (!st) {
		return -ENOMEM;
	}

	/* task->priority = priority;    Don't use in monotonic scheduler */
	task->magic = RT_TASK_MAGIC; 
	task->state = RT_TASK_DORMANT; 
	task->stack_bottom = st;
	task->stack = st + stack_size / sizeof(int);
	task->uses_fp = 0;
	task->identifier = id; /* Monotonic */

	*--(task->stack) = data;
	*--(task->stack) = data;
	*--(task->stack) = 0x200;	/* execute with interrupts enabled */
	*--(task->stack) = KERNEL_CS;
	*--(task->stack) = (int) fn;
	*--(task->stack) = (int) rt_startup;

	r_save_flags(flags);
	r_cli();
	task->next = rt_tasks;
	rt_tasks = task;
	r_restore_flags(flags);
	return 0;
}


void 
rt_schedule(void)
{
	RTIME now;
	RTIME preemption_time;
	RT_TASK *task;
	RT_TASK *new_task;
	RT_TASK *preemptor;
	RTIME 	shortest_period;

	int flags;

	r_save_flags(flags);
	r_cli();

#ifdef DEBUG
	now = rt_get_time();
	if (rt_current->identifier != -1) {
	    debug.state = EXEC;
	    debug.id    = rt_current->identifier;
	    debug.in    = init_time;
	    debug.out   = now;
	    rtf_put(DEBUG_FIFO, (char *) &debug,  sizeof(debug));
	}
#endif	

	for (task = rt_tasks; task; task = task->next) {
		if ( task->state == RT_TASK_DELAYED && 
		     task->resume_time < (now+10) ) {
			task->state = RT_TASK_READY;
		}
	}
	new_task = &rt_linux_task; 

/* begin rate-monotonic scheduling    */
	shortest_period = rt_linux_task.period;
      
	for (task = rt_tasks; task; task = task->next) {
	    if (task->state == RT_TASK_READY && 
	        task->period < shortest_period) {
		new_task = task;
		shortest_period = task->period;
	    }
	}

 	preemptor = 0;
	preemption_time = RT_TIME_END;
	for (task = rt_tasks; task; task = task->next) {
	    if (task->state == RT_TASK_DELAYED && 
	        task->resume_time < preemption_time) {
	    	preemption_time = task->resume_time;
	    	preemptor = task;
	    }
	}
/* End of rate-monotonic scheduler */

	if (preemptor) {
		rt_set_timer(preemption_time);
	} else {
		rt_no_timer();
	}

	if (new_task == rt_current) {
	  	r_restore_flags(flags);
		return;
	}

	if (new_task == &rt_linux_task) {
		SFIF = linux_irq_state;
	} else if (rt_current == &rt_linux_task) {
		linux_irq_state = SFIF;
		SFIF = 0;
	}

#ifdef DEBUG
	if (new_task->identifier != -1)	{	/* Monotonic scheduler */
		init_time = now;
	}
#endif

	new_task->state = RT_TASK_READY;
	rt_switch_to(new_task);
	r_restore_flags(flags);
}

#ifdef DEBUG
static void 
rt_print_request(RT_TASK *task){
	debug.state = SUSP;
	debug.id   = task->identifier;
	debug.in   = task->resume_time;
	debug.out  = task->resume_time+task->period;
	rtf_put(DEBUG_FIFO, (char *) &debug,  sizeof(debug));   
} 
#endif

int 
rt_task_delete(RT_TASK *task) {
    RT_TASK *t;
    int found = 0;
    long flags;

    r_save_flags(flags);
    r_cli();

    if (task->magic != RT_TASK_MAGIC) {
	r_restore_flags(flags);
	return -EINVAL;
    }

    if (task != rt_tasks) {
	for (t = rt_tasks; t; t = t->next) {
	    if (t->next == task) {
		t->next = task->next;
		found = 1;
		break;
	    }
	}
	if (!found) {
	    r_restore_flags(flags);
	    return -EINVAL;
	}
    } else 
	rt_tasks = task->next;

    task->magic = 0;
    r_restore_flags(flags);

    kfree(task->stack_bottom);
    rt_schedule();
    return 0;
}

int 
rt_task_suspend(RT_TASK *task)
{
	task->state = RT_TASK_DORMANT;
	rt_schedule();
	return 0;
}

int 
rt_task_wakeup(RT_TASK *task)
{
	task->state = RT_TASK_READY;
	rt_schedule();
	return 0;
}

int 
rt_task_wait(void)
{
	long flags;
	r_save_flags(flags);
	r_cli();
	rt_current->state = RT_TASK_DELAYED;
	rt_current->resume_time += rt_current->period;
#ifdef DEBUG
	rt_print_request(rt_current);
#endif
	rt_schedule();
	r_restore_flags(flags);
	return 0;
}

/* Rate-monotonic scheduler ( set priority ) */
int rt_task_make_periodic(RT_TASK *task, RTIME start_time, RTIME period)
{
	long flags;
	if (task->magic != RT_TASK_MAGIC) 
		return -EINVAL;
	
	r_save_flags(flags);
	r_cli();
	task->resume_time = start_time;
	task->period = period;
	task->state = RT_TASK_DELAYED;
#ifdef DEBUG
	rt_print_request(task);
#endif 
	r_restore_flags(flags);
	rt_schedule();
	return 0;
}


int 
init_module(void)
{
#ifdef DEBUG
	rtf_create(DEBUG_FIFO, 4000);
#endif
	rt_tasks = &rt_linux_task;
	rt_current = &rt_linux_task;
	rt_linux_task.priority = RT_LOWEST_PRIORITY;
	rt_linux_task.period   = RT_BIGGEST_PERIOD;
	rt_linux_task.next = 0;
	rt_linux_task.identifier = -1; /* Monotonic */
	rt_linux_task.state = RT_TASK_READY;
	rt_request_timer(&rt_schedule);
	return 0;
}

void 
cleanup_module(void)
{
	RT_TASK *t;
	RT_TASK *next_t;
#ifdef DEBUG
	rtf_destroy(DEBUG_FIFO);
#endif
	rt_free_timer();
	for (t = rt_tasks; t; t = next_t) {
		next_t = t->next;
		if (t != &rt_linux_task) {
			rt_task_delete(t);
		}
	}
}