《操作系统》的实验代码。
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#include <defs.h>
#include <list.h>
#include <proc.h>
#include <assert.h>
#include <default_sched.h>
static void
RR_init(struct run_queue *rq) {
list_init(&(rq->run_list));
rq->proc_num = 0;
}
static void
RR_enqueue(struct run_queue *rq, struct proc_struct *proc) {
assert(list_empty(&(proc->run_link)));
list_add_before(&(rq->run_list), &(proc->run_link));
if (proc->time_slice == 0 || proc->time_slice > rq->max_time_slice) {
proc->time_slice = rq->max_time_slice;
}
proc->rq = rq;
rq->proc_num ++;
}
static void
RR_dequeue(struct run_queue *rq, struct proc_struct *proc) {
assert(!list_empty(&(proc->run_link)) && proc->rq == rq);
list_del_init(&(proc->run_link));
rq->proc_num --;
}
static struct proc_struct *
RR_pick_next(struct run_queue *rq) {
list_entry_t *le = list_next(&(rq->run_list));
if (le != &(rq->run_list)) {
return le2proc(le, run_link);
}
return NULL;
}
static void
RR_proc_tick(struct run_queue *rq, struct proc_struct *proc) {
if (proc->time_slice > 0) {
proc->time_slice --;
}
if (proc->time_slice == 0) {
proc->need_resched = 1;
}
}
struct sched_class default_sched_class = {
.name = "RR_scheduler",
.init = RR_init,
.enqueue = RR_enqueue,
.dequeue = RR_dequeue,
.pick_next = RR_pick_next,
.proc_tick = RR_proc_tick,
};