3.4 The Sun UltraSPARC processor has multiple register sets. Describe what happens when a context switch occurs if the new context is already loaded into one of the register sets. What happens if the new context is in memory rather than in a register…

3.9 Describe the actions token by a kernel to content-switch between processes. 答案: 内核在进行进程上下文切换时, 首先将当前进程的上下文保存在内存中的PCB中, 然后再将下一个进程在内存中的PCB里的上下文读取出来. 上下文包含CPU寄存器里的内容, 堆, 用户栈, 内存管理信息, 数据, 文本.…

3.8 Describe the differences among short-term, medium-term, and longterm scheduling. 答案: 长期调度决定哪些进程进入到系统中,. 中期调度决定进入到系统中的进程哪些可以竞争处理器, 即哪些进程可以进入到就绪队列. 短期调度决定将处理器分配给就绪队列中的哪些进程. 扩展: 长期调度(long-term scheduling)又叫做高级调度(High-level scheduling)或作业调度(job sched…

3.12 Including the initial parent process, how many processes are created by the program shown in Figure 3.32? 答案: 共16个进程. 解析: 根据之前所学到的关于fork的知识去画进程图, 要注意的一点就是, fork的子进程的程序计数器里的指令和父进程的相同, 所以每次fork之后, 子进程里i的值都会继续增加.例如, 第一个进程, i=0时, fork的子进程的i会继续++, 从1…

3.5 When a process creates a new process using the fork() operation, which of the following state is shared between the parent process and the child process? a. Stack b.Heap c.Shared memory segments 答案:c.Shared memory segments. 解析:fork一个新的子进程时, 子进程会得…

3.3  Original version of Apple's mobile iOS operating system provied no means of concurrent processing. Discuss three major complications that concurrent processing adds to an operating system. 答案:此问题不太熟悉, 应该是问向操作系统中加入并发处理后的三个主要并发症是什么. 在网上搜索了一下, 得到了一…

3.2 Including the initial parent process, how many processes are created by the program shown in Figure? 答案: 会创建8个进程. 解析:相关知识: fork函数的执行原理 fork函数执行一次, 返回两次,父进程返回子进程的PID, 子进程返回0(至于返回值为什么不同, 这与do_fork函数有关,具体是怎么一回事我还不太清楚).程序中可利用此性质来区别程序的父进程和子进程. 当一个进程执行…

3.1 Using the program shown in the Figure3.30, explain what the output will be at LINE A 答案:LINE A 处的输出是PARENT: value = 5. 解析: 此问题的相关知识有进程创建.fork函数. 当父进程调用fork函数时, 新创建的子进程几乎但不完全与父进程相同, 子进程会获得一份父进程用户级虚拟地址空间的拷贝, 但是此拷贝是独立的, 拷贝内容包括文本.数据和bss段.堆以及用户栈. 所以在图…

这是原文链接http://serverfault.com/questions/190049/find-out-which-task-is-generating-a-lot-of-context-switches-on-linux 主要就是用pidstat -w 查看上下文切换, root@wis-virtual-machine:~# pidstat -w 1 Linux 4.2.0-16-generic (wis-virtual-machine)    2016年04月08日  _i686_  …

A thread is a Windows concept whose job is to virtualize the CPU. Thread Overhead Thread kernel object The operating system allocates and initializes one of these data structures for each thread created in the system. The data structure contains a bu…