lby/lk
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[kernel] add real time flag for threads

Browse Source 
Threads marked as real time do not have the preemption timer run against
them and will continue to run until they voluntarily yield or are
preempted by a higher priority thread from irq context.
This commit is contained in:
Travis Geiselbrecht
2014-08-25 21:41:08 -07:00
parent 489a3c561d
commit bba71af9ed
3 changed files with 81 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

63
kernel/thread.c
View File

@@ -200,6 +200,40 @@ thread_t *thread_create(const char *name, thread_start_routine entry, void *arg,
return thread_create_etc(NULL, name, entry, arg, priority, NULL, stack_size);
}
/**
* @brief Flag a thread as real time
*
* @param t Thread to flag
*
* @return NO_ERROR on success
*/
status_t thread_set_real_time(thread_t *t)
{
if (!t)
return ERR_INVALID_ARGS;
#if THREAD_CHECKS
ASSERT(t->magic == THREAD_MAGIC);
#endif
enter_critical_section();
#if PLATFORM_HAS_DYNAMIC_TIMER
if (t == get_current_thread()) {
/* if we're currently running, cancel the preemption timer. */
timer_cancel(&preempt_timer);
}
#endif
t->flags |= THREAD_FLAG_REAL_TIME;
exit_critical_section();
return NO_ERROR;
}
static bool thread_is_real_time(thread_t *t)
{
return !!(t->flags & THREAD_FLAG_REAL_TIME);
}
/**
* @brief Make a suspended thread executable.
*
@@ -450,13 +484,16 @@ void thread_resched(void)
#endif
#if PLATFORM_HAS_DYNAMIC_TIMER
/* if we're switching from idle to a real thread, set up a periodic
* timer to run our preemption tick.
*/
if (oldthread == idle_thread) {
if (thread_is_real_time(newthread)) {
if (!thread_is_real_time(oldthread)) {
/* if we're switching from a non real time to a real time, cancel
* the preemption timer. */
timer_cancel(&preempt_timer);
}
} else if (thread_is_real_time(oldthread)) {
/* if we're switching from a real time (or idle thread) to a regular one,
* set up a periodic timer to run our preemption tick. */
timer_set_periodic(&preempt_timer, 10, (timer_callback)thread_timer_tick, NULL);
} else if (newthread == idle_thread) {
timer_cancel(&preempt_timer);
}
#endif
@@ -584,14 +621,15 @@ enum handler_return thread_timer_tick(void)
{
thread_t *current_thread = get_current_thread();
if (current_thread == idle_thread)
if (thread_is_real_time(current_thread))
return INT_NO_RESCHEDULE;
current_thread->remaining_quantum--;
if (current_thread->remaining_quantum <= 0)
if (current_thread->remaining_quantum <= 0) {
return INT_RESCHEDULE;
else
} else {
return INT_NO_RESCHEDULE;
}
}
/* timer callback to wake up a sleeping thread */
@@ -714,9 +752,14 @@ void thread_set_priority(int priority)
*/
void thread_become_idle(void)
{
idle_thread = get_current_thread();
thread_set_name("idle");
thread_set_priority(IDLE_PRIORITY);
idle_thread = get_current_thread();
/* mark the idle thread as real time, to avoid running the preemption
* timer when it is scheduled. */
thread_set_real_time(idle_thread);
/* release the implicit boot critical section and yield to the scheduler */
exit_critical_section();