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sched: Properly account for timeslicing in tickless mode

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When adding a new runnable thread in tickless mode, we need to detect
whether it will timeslice with the runnable thread and reset the
timer, otherwise it won't get any CPU time until the next interrupt
fires at some indeterminate time in the future.

This fixes the specific bug discussed in #7193, but the broader
problem of tickless and timeslicing interacting badly remains.  The
code as it exists needs some rework to avoid all the #ifdef mess.

Note that the patch also moves _ready_thread() from a ksched.h inline
to sched.c.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2018-08-23 11:31:50 -07:00 • committed by Anas Nashif
commit bc6fb65c81
2 changed files with 16 additions and 10 deletions
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11
kernel/include/ksched.h
View file

@ -47,6 +47,7 @@ void *_get_next_switch_handle(void *interrupted);
struct k_thread *_find_first_thread_to_unpend(_wait_q_t *wait_q,
struct k_thread *from);
void idle(void *a, void *b, void *c);
void _ready_thread(struct k_thread *thread);
/* find which one is the next thread to run */
/* must be called with interrupts locked */
@ -216,16 +217,6 @@ static inline int _is_valid_prio(int prio, void *entry_point)
return 1;
}
static inline void _ready_thread(struct k_thread *thread)
{
if (_is_thread_ready(thread)) {
_add_thread_to_ready_q(thread);
}
sys_trace_thread_ready(thread);
}
static inline void _ready_one_thread(_wait_q_t *wq)
{
struct k_thread *th = _unpend_first_thread(wq);

15
kernel/sched.c
View file

@ -658,6 +658,21 @@ void _update_time_slice_before_swap(void)
}
#endif /* CONFIG_TIMESLICING */
void _ready_thread(struct k_thread *thread)
{
if (_is_thread_ready(thread)) {
_add_thread_to_ready_q(thread);
}
#if defined(CONFIG_TICKLESS_KERNEL) && !defined(CONFIG_SMP)
if (_is_thread_time_slicing(_get_next_ready_thread())) {
_set_time(_time_slice_duration);
}
#endif
sys_trace_thread_ready(thread);
}
int _unpend_all(_wait_q_t *waitq)
{
int need_sched = 0;