Linux操作系统进程调度算法的代码运行

由于Linux操作系统是开源的，因此其进程调度算法的代码可以在其代码库中找到。具体来说，Linux使用完全公平调度算法（CFS）作为其默认的进程调度算法，其代码实现可以在内核源代码中的sched目录中找到。以下是一些示例代码：

1. CFS调度器代码：

/*
* Completely Fair Scheduler
*
* This file contains the code for the Completely Fair Scheduler, a
* process scheduler based on a red-black tree. It implements a
* proportional-share scheduling algorithm with low latency for
* interactive tasks and high throughput for compute-bound tasks.
*
* Copyright (C) 2002-2007 Ingo Molnar <mingo@elte.hu>
* Copyright (C) 2007-2011 Con Kolivas <kernel@kolivas.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/

2. 调度策略代码：

/* Define a scheduling class */
static const struct sched_class fair_sched_class = {
.next = &idle_sched_class,
.enqueue_task = enqueue_task_fair,
.dequeue_task = dequeue_task_fair,
.yield_task = yield_task_fair,
.check_preempt_curr = check_preempt_wakeup,
.pick_next_task = pick_next_task_fair,
.put_prev_task = put_prev_task_fair,
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_fair,
.migrate_task_rq = migrate_task_rq_fair,
.task_waking = task_waking_fair,
.task_woken = task_woken_fair,
#endif
.set_curr_task = set_curr_task_fair,
.task_tick = task_tick_fair,
.task_fork = task_fork_fair,
.task_dead = task_dead_fair,
#ifdef CONFIG_FAIR_GROUP_SCHED
.task_move_group = task_move_group_fair,
#endif
};

3. 调度器初始化代码：

void __init sched_init(void)
{
int i;

/* Initialize the active and expired arrays for CFS */
for_each_possible_cpu(i) {
struct rq *rq = cpu_rq(i);
int j;

/* Initialize the red-black tree for CFS */
for (j = 0; j < MAX_NICE; j++) {
INIT_LIST_HEAD(&rq->cfs_rq[j].tasks);
INIT_LIST_HEAD(&rq->cfs_rq[j].runnable);
rb_init_node(&rq->cfs_rq[j].rb_node);
}
rq->cfs_rq[0].exec_clock = rq_clock(rq);
rq->cfs_rq[1].exec_clock = rq_clock(rq);
rq->cfs_rq[2].exec_clock = rq_clock(rq);
rq->cfs_rq[3].exec_clock = rq_clock(rq);
rq->cfs_rq[4].exec_clock = rq_clock(rq);
rq->cfs_rq[5].exec_clock = rq_clock(rq);
rq->cfs_rq[6].exec_clock = rq_clock(rq);
rq->cfs_rq[7].exec_clock = rq_clock(rq);
rq->cfs_rq[8].exec_clock = rq_clock(rq);
rq->cfs_rq[9].exec_clock = rq_clock(rq);
rq->cfs_rq[10].exec_clock = rq_clock(rq);
rq->cfs_rq[11].exec_clock = rq_clock(rq);
rq->cfs_rq[12].exec_clock = rq_clock(rq);
rq->cfs_rq[13].exec_clock = rq_clock(rq);
rq->cfs_rq[14].exec_clock = rq_clock(rq);
rq->cfs_rq[15].exec_clock = rq_clock(rq);
rq->nr_running = 0;
rq->nr_uninterruptible = 0;
rq->curr = NULL;
INIT_LIST_HEAD(&rq->migration_queue);
INIT_LIST_HEAD(&rq->expired);
INIT_LIST_HEAD(&rq->active);
rq->expired_timestamp = 0;
rq->next_balance = jiffies + HZ;
rq->skip_clock_update = 0;
rq->idle_stamp = rq_clock(rq);
rq->last_moved = jiffies;
spin_lock_init(&rq->lock);
spin_lock_init(&rq->task_lock);
}

/* Initialize the idle class */
init_idle(&init_task);
init_idle(&ksoftirqd_task);
init_idle(&migration_thread);

/* Initialize the fair class */
sched_register_scheduler(&fair_sched_class);
}