#define TASK_NAME_SIZE 32
-#define TASK_MAX_PRIORITY 99
-
#define TASK_MAGIC 0xAABBCCDD11223344
+// 每个时间片（quantum）包含的时钟滴答数；任务连续运行的上限
+#define TASK_TICKS_PER_QUANTUM 3
+
#define NR_TASK_OPEN_CNT 32
typedef struct task_files {
// 暂时先不用bitmap，直接线性搜索
uint32_t esp;
uint32_t eip;
- int ticks;
-
+ // [0, 100)
+ // 0 最高 99 最低
int priority;
pid_t pid;
list_head_t ready_list; // 就绪队列
list_head_t waitq_list;
+ int ticks_left; // 时间片剩余
+
+ // 仅用于统计
+ uint32_t st_ticks;
uint32_t sched_cnt; // 被调度换上CPU的次数
uint32_t sched_keep_cnt; // 时间片到了，但是没有被换出，又重新执行的次数
#define get_tsk_from_list(p) list_entry((p), Task, list)
#define del_tsk_from_list(tsk) list_del((&tsk->list))
-void task_set_run(task_t* t);
+// void task_set_run(task_t* t);
void task_set_ready(task_t* t);
void task_set_wait(task_t* t);
extern pde_t __initdata init_pgd[PDECNT_PER_PAGE] __attribute__((__aligned__(PAGE_SIZE)));
LIST_HEAD(all_tasks);
-LIST_HEAD(ready_tasks);
+// LIST_HEAD(ready_tasks);
void init_root_task() {
int i;
root_task.ppid = 0;
root_task.state = TASK_RUN;
root_task.reason = "root";
- root_task.priority = 7;
- root_task.ticks = root_task.priority;
+ root_task.priority = TASK_PRIORITY_MAX;
+ root_task.ticks_left = 1;
+ root_task.st_ticks = 0;
root_task.vma_list = NULL;
root_task.sched_cnt = 0;
root_task.sched_keep_cnt = 0;
kmem_cache_t* task_t_cache;
+static priority_readyq_t g_priority_readyq;
+void priority_readyq_init(priority_readyq_t* readyq) {
+ for (int i = 0; i < TASK_PRIORITY_CNT; i++) {
+ list_init(&readyq->lists[i]);
+ }
+
+ for (int i = 0; i < READYQ_BITMAP_WORD_CNT; i++) {
+ readyq->bitmap[i] = 0;
+ }
+}
+
+static void priority_readyq_set_bit(int priority) {
+ int item_index = priority / READYQ_BITS_PER_WORD;
+ int bit_index = priority % READYQ_BITS_PER_WORD;
+ g_priority_readyq.bitmap[item_index] |= (1U << bit_index);
+}
+
+static void priority_readyq_clear_bit(int priority) {
+ int item_index = priority / READYQ_BITS_PER_WORD;
+ int bit_index = priority % READYQ_BITS_PER_WORD;
+ g_priority_readyq.bitmap[item_index] &= ~(1U << bit_index);
+}
+
+void task_reset_priority(int priority) {
+ assert(priority >= TASK_PRIORITY_MIN);
+ assert(priority <= TASK_PRIORITY_MAX);
+
+ task_t* task = current;
+
+ if (task->priority == priority) {
+ return;
+ }
+
+ // unsigned long eflags;
+ // irq_save(eflags);
+
+ // 只有当前运行的Task才能调整priority
+ // 而它在调度器调度运行时已经从队列上取下了
+ // 运行时不在任何队列上，所以只需要直接调整
+
+ current->priority = priority;
+
+ // irq_restore(eflags);
+
+ // 降低优先级应该触发调度
+ // 这里简单实现，更复杂的实现，应该是看有没有比priority更高的任务在就绪队列上再决定要不要重新调度
+ if (current->priority < priority) {
+ set_need_schedule();
+ }
+}
+
void setup_tasks() {
INIT_LIST_HEAD(&all_tasks);
- INIT_LIST_HEAD(&ready_tasks);
+ // INIT_LIST_HEAD(&ready_tasks);
+
+ priority_readyq_init(&g_priority_readyq);
init_root_task();
: "memory");
}
+task_t* pick_next_task() {
+ int index = -1; // 代表所有READY队列都为空
+ for (int i = 0; i < READYQ_BITMAP_WORD_CNT; i++) {
+ if (g_priority_readyq.bitmap[i] != 0) {
+ index = __builtin_ctz(g_priority_readyq.bitmap[i]);
+
+ index += i * READYQ_BITS_PER_WORD;
+ break;
+ }
+ }
+
+ if (index == -1) {
+ return NULL;
+ }
+
+ assert(index >= 0);
+ assert(index < TASK_PRIORITY_CNT);
+
+ // 对应的优先级队列必定不为空
+ list_head_t* list = g_priority_readyq.lists + index;
+ assert(!list_empty(list));
+
+ // 返回队列头部第一个任务
+ task_t* task = list_entry(list->next, task_t, ready_list);
+ assert(task != NULL);
+ assert(task->priority == index);
+ assert(task != &root_task);
+ assert(task->priority >= TASK_PRIORITY_MIN);
+ assert(task->priority <= TASK_PRIORITY_MAX);
+ assert(task->state == TASK_READY);
+
+ return task;
+}
+
void schedule() {
task_t* prev = current;
task_t* next = NULL;
task_set_ready(prev);
}
+ next = pick_next_task();
+
+ if (next == NULL) {
+ next = &root_task;
+ next->ticks_left = 1;
+ } else {
+ list_del_init(&next->ready_list);
+ next->state = TASK_RUN;
+ if (next->ticks_left <= 0) {
+ next->ticks_left = TASK_TICKS_PER_QUANTUM;
+ }
+ if (list_empty(g_priority_readyq.lists + next->priority)) {
+ priority_readyq_clear_bit(next->priority);
+ }
+ }
+
+#if 0
if (list_empty(&ready_tasks)) {
next = &root_task;
goto end;
end:
task_set_run(next);
-
- if (prev->ticks <= 0) {
- prev->ticks = prev->priority;
- }
+#endif
clear_need_schedule();
monitor_tasks[id] = tsk;
}
-void task_set_run(task_t* t) {
- assert(t != NULL);
+// void task_set_run(task_t* t) {
+// assert(t != NULL);
- // if (t == &root_task) {
- // t->state = TASK_RUN;
- // return;
- // }
+// // if (t == &root_task) {
+// // t->state = TASK_RUN;
+// // return;
+// // }
- assert(t->state == TASK_READY);
+// assert(t->state == TASK_READY);
- unsigned long eflags;
- irq_save(eflags);
+// unsigned long eflags;
+// irq_save(eflags);
- list_del_init(&t->ready_list);
- t->state = TASK_RUN;
+// list_del_init(&t->ready_list);
+// t->state = TASK_RUN;
- irq_restore(eflags);
-}
+// irq_restore(eflags);
+// }
void task_set_ready(task_t* t) {
assert(t != NULL);
unsigned long eflags;
irq_save(eflags);
+
+ //
if (!list_empty(&t->ready_list)) {
list_del_init(&t->ready_list);
}
- list_add_tail(&t->ready_list, &ready_tasks);
+
+ //
+ assert(t->priority >= TASK_PRIORITY_MIN);
+ assert(t->priority <= TASK_PRIORITY_MAX);
+ list_head_t* list = g_priority_readyq.lists + t->priority;
+ list_add_tail(&t->ready_list, list);
+ priority_readyq_set_bit(t->priority);
t->state = TASK_READY;
+
irq_restore(eflags);
}