blob: 401bcea0c7c4b8bf9b2708bdcdb0f34ecdfd33e4 [file] [log] [blame]
/*
* Copyright (c) 2018, 2024 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
#include <kswap.h>
#include <ksched.h>
#include <ipi.h>
static int slice_ticks = DIV_ROUND_UP(CONFIG_TIMESLICE_SIZE * Z_HZ_ticks, Z_HZ_ms);
static int slice_max_prio = CONFIG_TIMESLICE_PRIORITY;
static struct _timeout slice_timeouts[CONFIG_MP_MAX_NUM_CPUS];
static bool slice_expired[CONFIG_MP_MAX_NUM_CPUS];
#ifdef CONFIG_SWAP_NONATOMIC
/* If z_swap() isn't atomic, then it's possible for a timer interrupt
* to try to timeslice away _current after it has already pended
* itself but before the corresponding context switch. Treat that as
* a noop condition in z_time_slice().
*/
struct k_thread *pending_current;
#endif
static inline int slice_time(struct k_thread *thread)
{
int ret = slice_ticks;
#ifdef CONFIG_TIMESLICE_PER_THREAD
if (thread->base.slice_ticks != 0) {
ret = thread->base.slice_ticks;
}
#else
ARG_UNUSED(thread);
#endif
return ret;
}
bool thread_is_sliceable(struct k_thread *thread)
{
bool ret = thread_is_preemptible(thread)
&& slice_time(thread) != 0
&& !z_is_prio_higher(thread->base.prio, slice_max_prio)
&& !z_is_thread_prevented_from_running(thread)
&& !z_is_idle_thread_object(thread);
#ifdef CONFIG_TIMESLICE_PER_THREAD
ret |= thread->base.slice_ticks != 0;
#endif
return ret;
}
static void slice_timeout(struct _timeout *timeout)
{
int cpu = ARRAY_INDEX(slice_timeouts, timeout);
slice_expired[cpu] = true;
/* We need an IPI if we just handled a timeslice expiration
* for a different CPU. Ideally this would be able to target
* the specific core, but that's not part of the API yet.
*/
if (IS_ENABLED(CONFIG_SMP) && cpu != _current_cpu->id) {
flag_ipi();
}
}
void z_reset_time_slice(struct k_thread *thread)
{
int cpu = _current_cpu->id;
z_abort_timeout(&slice_timeouts[cpu]);
slice_expired[cpu] = false;
if (thread_is_sliceable(thread)) {
z_add_timeout(&slice_timeouts[cpu], slice_timeout,
K_TICKS(slice_time(thread) - 1));
}
}
void k_sched_time_slice_set(int32_t slice, int prio)
{
K_SPINLOCK(&_sched_spinlock) {
slice_ticks = k_ms_to_ticks_ceil32(slice);
slice_max_prio = prio;
z_reset_time_slice(_current);
}
}
#ifdef CONFIG_TIMESLICE_PER_THREAD
void k_thread_time_slice_set(struct k_thread *thread, int32_t thread_slice_ticks,
k_thread_timeslice_fn_t expired, void *data)
{
K_SPINLOCK(&_sched_spinlock) {
thread->base.slice_ticks = thread_slice_ticks;
thread->base.slice_expired = expired;
thread->base.slice_data = data;
}
}
#endif
/* Called out of each timer interrupt */
void z_time_slice(void)
{
k_spinlock_key_t key = k_spin_lock(&_sched_spinlock);
struct k_thread *curr = _current;
#ifdef CONFIG_SWAP_NONATOMIC
if (pending_current == curr) {
z_reset_time_slice(curr);
k_spin_unlock(&_sched_spinlock, key);
return;
}
pending_current = NULL;
#endif
if (slice_expired[_current_cpu->id] && thread_is_sliceable(curr)) {
#ifdef CONFIG_TIMESLICE_PER_THREAD
if (curr->base.slice_expired) {
k_spin_unlock(&_sched_spinlock, key);
curr->base.slice_expired(curr, curr->base.slice_data);
key = k_spin_lock(&_sched_spinlock);
}
#endif
if (!z_is_thread_prevented_from_running(curr)) {
move_thread_to_end_of_prio_q(curr);
}
z_reset_time_slice(curr);
}
k_spin_unlock(&_sched_spinlock, key);
}