SunnyBeiKe的专栏

/* * schedule() is the main scheduler function. */asmlinkage void __sched schedule(void){ struct task_struct *prev, *next; unsigned long *switch_count; struct rq *rq; int cpu;need_resched:

/* * All the scheduling class methods: */static const struct sched_class fair_sched_class = { .next = &idle_sched_class, //指向下一个调度器 .enqueue_task = enqueue_task_fair, .dequeue_task = dequeu

想比于前面文章讲到的CFS的调度器，RT调度器就简单许多，RT的调度算法也相应的简单很多。static const struct sched_class rt_sched_class = { .next = &fair_sched_class, .enqueue_task = enqueue_task_rt, .dequeue_task = dequeue_task_rt,

在挑选得到了下一个即将被调度进来的进程之后，如果被选中的进程不是当前正在运行的进程，那么需要进行上下文切换以执行被选中的进程：        context_switch(rq, prev, next); /* unlocks the rq */        /*         * The context switch have flipped the stack from und

我们知道了进程是如何被调度了，但是进程什么时候会被调度呢？在什么情况下被调度呢？调度只有当CPU在内核中运行时才有可能发生。有两种情况：（1）“自愿”的，通过像sleep()之类的系统调用实现；或者实在通过其他系统调用进入内核以后因某种原因受阻需要等待，而自愿让内核调度其他进程执行。（2）“强制”的，当一个进程连续运行的时间超过一定的限度时，内核就会强制地调度其他进程来执行。《情景分析》P23

/** * yield - yield the current processor to other threads. * * This is a shortcut for kernel-space yielding - it marks the * thread runnable and calls sys_sched_yield(). */void __sched yield(vo

/* * Pick up the highest-prio task: */static inline struct task_struct *pick_next_task(struct rq *rq){ const struct sched_class *class; struct task_struct *p; /* * Optimization: we know tha

/* * Ok, this is the main fork-routine. * * It copies the process, and if successful kick-starts * it and waits for it to finish using the VM if required. */long do_fork(unsigned long clone_fla

static int copy_mm(unsigned long clone_flags, struct task_struct * tsk){ struct mm_struct * mm, *oldmm; int retval; tsk->min_flt = tsk->maj_flt = 0; tsk->nvcsw = tsk->nivcsw = 0;#ifdef CONFIG_D

/* * sys_execve() executes a new program. */long sys_execve(const char __user *name, //需要执行的文件的绝对路径（存于用户空间） const char __user *const __user *argv, //传入系统调用的参数（存于用户空间） const ch

可以参看UNIX环境高级编程的相关章节。为了搞清楚进程组之间的关系，我们做如下的实验：编写程序：/*test.c*/#include "../include/apue.h"void main() { pid_t pid; char *args[] = {"/bin/echo", "Hello", "World!", NULL }; if((pid = fork()

/* * Send signals to all our closest relatives so that they know * to properly mourn(悼念) us.. */static void exit_notify(struct task_struct *tsk, int group_dead){ int signal; void *cookie; /*

struct task_struct { volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */ void *stack; //stack should points to a threadinfo struct atomic_t usage; //有几个进程正在使用该结构 unsigned int flags; /

static struct task_struct *dup_task_struct(struct task_struct *orig){ struct task_struct *tsk; //sizeof(task_struct) = 3236;这个值是通过gdb得到的， //可以看到单个的task_struct

/* * This creates a new process as a copy of the old one, * but does not actually start it yet. * * It copies the registers, and all the appropriate * parts of the process environment (as per the

NORET_TYPE void do_exit(long code){ struct task_struct *tsk = current; int group_dead; profile_task_exit(tsk); WARN_ON(atomic_read(&tsk->fs_excl)); //如果进程holding fs exclusive resources，则报错。但是还