原版的操作系统_精髓与设计原理_第5版Chapter14
操作系统基础第五版课件
第四代操作系统（1990s 至今）
以微处理器和网络为主要特征 ，出现了多媒体、网络和安全 等新技术。
操作系统的分类与应用领域
分类
根据操作系统的功能和结构，可以将 其分为批处理系统、分时系统、实时 系统、网络操作系统和分布式操作系 统等。
网络协议
TCP、UDP、HTTP、FTP等常 见网络协议的原理和应用场景 。
网络设备
路由器、交换机、网卡等网络 设备的工作原理和功能。
网络通信性能
带宽、延迟、丢包率等网络通 信性能指标的含义和影响因素
。
分布式系统的特点与挑战
分布式系统的定义与特点
资源共享、并发性、自治性、透明性等。
分布式文件系统
HDFS、Google File System等分布式文件 系统的原理和应用。
02
同步与互斥
分布式系统中的同步与互斥问题及 解决方案。
一致性与复制
分布式系统中数据一致性的维护策 略及数据复制技术。
04
THANKS
感谢观看
回收策略
设备使用完毕后及时回收，避免资源浪费。可采用基于计时器、计 数器或事件的回收机制。
06
并发编程与死锁处理
并发编程的概念与优势
并发编程概念
并发编程是指在一段时间内宏观上有多个程序在同时运行，但实际上每个程序只是在CPU分配的时间片内运行。
并发编程优势
提高CPU利用率、加快程序执行速度、实现多任务处理等。
优先级调度
为每个进程设置优先级，根据优先级 进行调度，可灵活调整调度策略。
进程同步与通信机制
进程同步
通过信号量、互斥锁等机制实现进程间的协调运 行，避免竞争条件和死锁问题。
操作系统基础clz第五版课件
目录
CONTENTS
• 内存管理 • 文件系统 • 设备管理 • 安全与保护
01 操作系统概述
操作系统的定义与功能
总结词
操作系统是计算机系统的核心软件，负责管理计算机硬件和 应用程序，提供计算机系统的稳定、高效运行环境。
详细描述
操作系统是一种系统软件，负责管理计算机硬件和应用程序， 提供计算机系统的稳定、高效运行环境。它负责分配和回收 硬件资源，管理计算机系统的数据和文件，提供用户界面和 系统服务等功能。
控制设备
控制设备的启动、执行和结束，确保 设备按照正确的顺序和方式工作。
设备管理的功能与任务
• 维护设备：记录设备的状态和使用情况，进行必要的维护 和修理，保证设备的正常运行。
设备管理的功能与任务
实现设备的独立性
通过抽象和接口，使应用程序与设备无关，简化 设备的使用和管理。
提高设备的利用率
合理地调度设备和处理设备请求，减少设备的空 闲时间，提高设备的利用率。
要点一
访问控制机制
操作系统中的访问控制机制用于确定哪些用户或程序可以 访问哪些资源，以及他们可以执行哪些操作。
要点二
控制策略
常见的访问控制策略包括基于角色的访问控制（RBAC）、 基于属性的访问控制（ABAC）和强制访问控制（MAC）。
操作系统的加密与解密技术
加密与解密技术
加密和解密技术用于保护数据的机密性和完整性，防止 未经授权的访问和篡改。
文件保 护
文件保护是指通过权限控制和加密等方式保护文件的安全，防止未 经授权的访问和修改。
访问控制机制
访问控制机制是实现文件共享和保护的重要手段，它通过控制用户或 进程对文件的访问权限来保护文件的安全和完整性。
原版的操作系统-精髓与设计原理-第5版Chapter06【可编辑全文】
Concurrency: Deadlock and Concurrency:Deadlock andStarvationChapter6Chapter 61Deadlock •Permanent blocking of a set of processes P bl ki f fthat either compete for system resources or communicate with each other•No efficient solutionNo efficient solution•Involve conflicting needs for resources by two or more processes2345Reusable ResourcesReusable Resources •Used by only one process at a time and notU d b l t ti d t depleted by that use•Processes obtain resources that they later release for reuse by other processes •Processors, I/O channels, main and secondary memory, devices, and data structures such as yfiles, databases, and semaphoresDeadlock occurs if each process holds one •Deadlock occurs if each process holds one resource and requests the other6Example of Deadlock Example of Deadlock7Another Example of Deadlock Another Example of Deadlock S i il bl f ll i f •Space is available for allocation of 200Kbytes, and the following sequence of events occurP1P2. . .. . .Request 80 Kbytes;R 60Kb . . .. . .Request 70 Kbytes;R 80Kb Deadlock occurs if both processes Request 60 Kbytes;Request 80 Kbytes;•Deadlock occurs if both processes progress to their second request8Consumable ResourcesConsumable Resources •Created (produced) and destroyedC d(d d)d d d (consumed)•Interrupts, signals, messages, and information in I/O buffersinformation in I/O buffers•Deadlock may occur if a Receive message is blockingMay take a rare combination of events to •May take a rare combination of events to cause deadlock9Example of DeadlockExample of DeadlockD dl k if i i bl ki •Deadlock occurs if receive is blockingP1 . . .P2 . . .. . .Receive(P2); Send(P2, M1);. . .Receive(P1);Send(P1, M2);10Resource Allocation Graphs Resource Allocation Graphs •Directed graph that depicts a state of theDi t d h th t d i t t t f th system of resources and processes11Resource Allocation Graphs Resource Allocation Graphs12Conditions for DeadlockConditions for Deadlock •Mutual exclusionM l l i–Only one process may use a resource at atimeHold and wait•Hold-and-wait–A process may hold allocated resourceswhile awaiting assignment of otherswhile awaiting assignment of others•No preemption–No resource can be forcibly removed form ap gprocess holding it13Conditions for DeadlockConditions for Deadlock •Circular waitCi l it–A closed chain of processes exists, such that eachprocess holds at least one resource needed by theh ld t l t d d b thnext process in the chain1415Possibility of DeadlockPossibility of Deadlock •Mutual ExclusionM l E l ip p•No preemption•Hold and wait16Existence of DeadlockExistence of Deadlock •Mutual ExclusionM l E l ip p•No preemption•Hold and wait•Circular wait17Deadlock PreventionDeadlock Prevention •Mutual ExclusionM l E l i–Must be supported by the operating system •Hold and Wait–Require a process request all of its requiredRequire a process request all of its requiredresources at one time18Deadlock PreventionDeadlock Prevention•No PreemptionN P i–Process must release resource and requestagainOpe g sys e y p ee p p ocess o –Operating system may preempt a process torequire it releases its resources •Circular WaitCircular Wait–Define a linear ordering of resource types19Deadlock AvoidanceDeadlock Avoidance•A decision is made dynamically whether A d i i i d d i ll h h the current resource allocation request will, if granted, potentially lead to ade d ocdeadlock•Requires knowledge of future processtrequest20Two Approaches toDeadlock Avoidance •Do not start a process if its demandsD if i d dmight lead to deadlock•Do not grant an incremental resourcerequest to a process if this allocation request to a process if this allocationmight lead to deadlock21Resource Allocation Denial Resource Allocation Denial •Referred to as the banker’s algorithmR f d h b k’l i hy•State of the system is the current allocation of resources to process •Safe state is where there is at least one S f t t i h th i t l t sequence that does not result in deadlock •Unsafe state is a state that is not safe22Initial State23P2 Runs to Completion24P1 Runs to Completion25P3 Runs to Completion26Unsafe State27Unsafe State28Deadlock Avoidance Logic Deadlock Avoidance Logic29Deadlock Avoidance Logic Deadlock Avoidance Logic30Deadlock AvoidanceDeadlock Avoidance •Maximum resource requirement must be M i i t t b stated in advance•Processes under consideration must be independent; no synchronization requirements•There must be a fixed number ofThere must be a fixed number of resources to allocate•No process may exit while holdingNo process may exit while holding resources31Deadlock Detection Deadlock Detection32Strategies once DeadlockDetected•Abort all deadlocked processesAb t ll d dl k d•Back up each deadlocked process to some previously defined checkpoint, and restart all process–Original deadlock may occur •Successively abort deadlocked processes Successively abort deadlocked processes until deadlock no longer exists •Successively preempt resources until Successively preempt resources until deadlock no longer exists33Selection Criteria DeadlockedProcesses•Least amount of processor timeL f i consumed so far•Least number of lines of output produced so farproduced so far•Most estimated time remaining •Least total resources allocated so far •Lowest priorityLowest priority34Strengths and Weaknesses of theStrategies35Dining Philosophers Problem Dining Philosophers Problem36Dining Philosophers Problem Dining Philosophers Problem37Dining Philosophers Problem Dining Philosophers Problem38Dining Philosophers Problem Dining Philosophers Problem39Dining Philosophers Problem Dining Philosophers Problem40UNIX ConcurrencyMechanisms•PipesPig•Messages•Shared memory•Semaphores•Signals4142Linux Kernel ConcurrencyMechanisms •Includes all the mechanisms found in I l d ll h h i f d i UNIX•Atomic operations execute without interruption and without interference interruption and without interference43Linux Atomic Operations Linux Atomic Operations44Linux Atomic Operations Linux Atomic Operations45Linux Kernel ConcurrencyMechanisms •SpinlocksS i l k–Used for protecting a critical section4647Linux Kernel ConcurrencyMechanisms48Solaris Thread Synchronization Primitives •Mutual exclusion (mutex) locksM l l i()l kp•Semaphores•Multiple readers, single writer (readers/writer) locks(d/it)l k•Condition variables4950。
操作系统精髓与设计原理
操作系统精髓与设计原理在我们日常使用电脑、手机等电子设备时，操作系统是那个默默工作但又至关重要的幕后英雄。
它管理着设备的硬件资源，为我们运行的各种应用程序提供了一个稳定、高效的环境。
那么，操作系统的精髓究竟是什么？它的设计原理又包含哪些关键要素呢？要理解操作系统的精髓，首先得明白它的核心任务——资源管理。
操作系统就像是一个大管家，负责合理地分配和调度计算机的各种资源，包括处理器、内存、存储设备、输入输出设备等等。
想象一下，如果没有操作系统来协调这些资源，各个程序就会像一群没有指挥的士兵，争抢有限的资源，导致整个系统陷入混乱。
以处理器资源为例，操作系统通过进程调度算法，决定哪个程序在什么时候获得处理器的使用权。
这样可以确保每个程序都能得到公平的机会运行，同时避免某个程序长时间独占处理器而导致其他程序无法响应。
常见的进程调度算法有先来先服务、短作业优先、时间片轮转等。
这些算法根据不同的需求和场景，权衡了公平性、响应时间和系统效率等因素。
内存管理也是操作系统的重要职责之一。
它要确保程序能够安全、高效地使用内存。
操作系统通过虚拟内存技术，让程序以为自己拥有了大片连续的内存空间，实际上是在物理内存和磁盘之间进行灵活的页面交换。
这样，即使物理内存有限，也能运行大型的程序。
同时，操作系统还负责内存的分配和回收，避免内存泄漏和碎片问题。
除了资源管理，操作系统还提供了一个抽象的接口，让用户和应用程序能够更方便地与硬件进行交互。
比如，我们不需要了解磁盘的具体读写机制，只需要通过操作系统提供的文件系统来进行文件的创建、读取和删除操作。
这种抽象化大大降低了使用计算机的难度，提高了开发效率。
在操作系统的设计原理中，并发和并行是两个关键概念。
并发是指多个程序在同一时间段内交替执行，而并行则是指多个程序在同一时刻同时执行。
操作系统通过进程和线程机制来实现并发和并行。
进程是程序的一次执行过程，而线程是进程中的执行单元。
通过合理地创建和管理进程和线程，操作系统能够充分利用多核处理器的优势，提高系统的性能。
操作系统精髓与设计原理第五版习题与答案
第1章计算机系统概述1.1 列出并简要地定义计算机的四个主要组成部分。
主存储器，存储数据和程序；算术逻辑单元，能处理二进制数据；控制单元，解读存储器中的指令并且使他们得到执行；输入/输出设备，由控制单元管理。
1.2 定义处理器寄存器的两种主要类别。
用户可见寄存器：优先使用这些寄存器，可以使机器语言或者汇编语言的程序员减少对主存储器的访问次数。
对高级语言而言，由优化编译器负责决定把哪些变量应该分配给主存储器。
一些高级语言，如C语言，允许程序言建议编译器把哪些变量保存在寄存器中。
控制和状态寄存器：用以控制处理器的操作，且主要被具有特权的操作系统例程使用，以控制程序的执行。
1.3 一般而言，一条机器指令能指定的四种不同操作是什么？处理器－寄存器：数据可以从处理器传送到存储器，或者从存储器传送到处理器。
处理器－I/O：通过处理器和I/O模块间的数据传送，数据可以输出到外部设备，或者从外部设备输入数据。
数据处理：处理器可以执行很多关于数据的算术操作或逻辑操作。
控制：某些指令可以改变执行顺序。
1.4 什么是中断？中断：其他模块（I/O，存储器）中断处理器正常处理过程的机制。
1.5 多中断的处理方式是什么？处理多中断有两种方法。
第一种方法是当正在处理一个中断时，禁止再发生中断。
第二种方法是定义中断优先级，允许高优先级的中断打断低优先级的中断处理器的运行。
1.6 存层次的各个元素间的特征是什么？存储器的三个重要特性是：价格，容量和访问时间。
1.7 什么是高速缓冲存储器？高速缓冲存储器是比主存小而快的存储器，用以协调主存跟处理器，作为最近储存地址的缓冲区。
1.8 列出并简要地定义I/O操作的三种技术。
可编程I/O：当处理器正在执行程序并遇到与I/O相关的指令时，它给相应的I/O模块发布命令（用以执行这个指令）；在进一步的动作之前，处理器处于繁忙的等待中，直到该操作已经完成。
中断驱动I/O：当处理器正在执行程序并遇到与I/O相关的指令时，它给相应的I/O模块发布命令，并继续执行后续指令，直到后者完成，它将被I/O 模块中断。
操作系统精髓与设计原理第五版 课后题答案
操作系统精髓与设计原理第五版课后题答案C HAPTER 2O PERATING S YSTEMO VERVIEWReview Questions2.1 Convenience: An operating system makes a computer more convenientto use. Efficiency: An operating system allows the computer systemresources to be used in an efficient manner. Ability to evolve: Anoperating system should be constructed in such a way as to permit theeffective development, testing, and introduction of new systemfunctions without interfering with service.2.5 The execution context, or process state, is the internal data by which theoperating system is able to supervise and control the process. Thisinternal information is separated from the process, because theoperating system has information not permitted to the process. Thecontext includes all of the information that the operating system needsto manage the process and that the processor needs to execute theprocess properly. The context includes the contents of the variousprocessor registers, such as the program counter and data registers. Italso includes information of use to the operating system, such as thepriority of the process and whether the process is waiting for thecompletion of a particular I/O event.Problems2.1 The answers are the same for (a) and (b). Assume that althoughprocessor operations cannot overlap, I/O operations can.1 Job: TAT = NT Processor utilization = 50%2 Jobs: TAT = NT Processor utilization = 100%4 Jobs: TAT = (2N – 1)NT Processor utilization = 100% 2.4 A system call is used by an application program to invoke a functionprovided by the operating system. Typically, the system call results intransfer to a system program that runs in kernel mode.C HAPTER 3P ROCESS D ESCRIPTION ANDC ONTROLReview Questions3.5 Swapping involves moving part or all of a process from main memoryto disk. When none of the processes in main memory is in the Ready state, the operating system swaps one of the blocked processes out onto disk into a suspend queue, so that another process may be brought into main memory to execute.3.10 The user mode has restrictions on the instructions that can be executedand the memory areas that can be accessed. This is to protect theoperating system from damage or alteration. In kernel mode, theoperating system does not have these restrictions, so that it canperform its tasks.Problems3.1 •Creation and deletion of both user and system processes. Theprocesses in the system can execute concurrently for informationsharing, computation speedup, modularity, and convenience.Concurrent execution requires a mechanism for process creation and deletion. The required resources are given to the process when it iscreated, or allocated to it while it is running. When the processterminates, the OS needs to reclaim any reusable resources.•Suspension and resumpti on of processes. In process scheduling, theOS needs to change the process's state to waiting or ready state when it is waiting for some resources. When the required resources areavailable, OS needs to change its state to running state to resume itsexecution.•Provision of mechanism for process synchronization. Cooperatingprocesses may share data. Concurrent access to shared data mayresult in data inconsistency. OS has to provide mechanisms forprocesses synchronization to ensure the orderly execution ofcooperating processes, so that data consistency is maintained.•Provision of mechanism for process communication. The processesexecuting under the OS may be either independent processes orcooperating processes. Cooperating processes must have the meansto communicate with each other.•Provision of mechanisms for deadlock handling. In amultiprogramming environment, several processes may compete fora finite number of resources. If a deadlock occurs, all waitingprocesses will never change their waiting state to running state again, resources are wasted and jobs will never be completed.3.3Figure 9.3 shows the result for a single blocked queue. The figurereadily generalizes to multiple blocked queues.C HAPTER 4P ROCESS D ESCRIPTION ANDC ONTROLReview Questions4.2 Less state information is involved.4.5 Address space, file resources, execution privileges are examples.4.6 1. Thread switching does not require kernel mode privileges becauseall of the thread management data structures are within the useraddress space of a single process. Therefore, the process does notswitch to the kernel mode to do thread management. This saves theoverhead of two mode switches (user to kernel; kernel back to user). 2.Scheduling can be application specific. One application may benefit most from a simple round-robin scheduling algorithm, while another might benefit from a priority-based scheduling algorithm. Thescheduling algorithm can be tailored to the application withoutdisturbing the underlying OS scheduler. 3. ULTs can run on anyoperating system. No changes are required to the underlying kernel to support ULTs. The threads library is a set of application-level utilities shared by all applications.4.7 1. In a typical operating system, many system calls are blocking. Thus,when a ULT executes a system call, not only is that thread blocked, but also all of the threads within the process are blocked. 2. In a pure ULT strategy, a multithreaded application cannot take advantage ofmultiprocessing. A kernel assigns one process to only one processor ata time. Therefore, only a single thread within a process can execute at atime.Problems4.2Because, with ULTs, the thread structure of a process is not visible to theoperating system, which only schedules on the basis of processes.C HAPTER 5C ONCURRENCY:M UTUALE XCLUSION ANDS YNCHRONIZATIONReview Questions5.1 Communication among processes, sharing of and competing forresources, synchronization of the activities of multiple processes, and allocation of processor time to processes.5.9 A binary semaphore may only take on the values 0 and 1. A generalsemaphore may take on any integer value.Problems5.2 ABCDE; ABDCE; ABDEC; ADBCE; ADBEC; ADEBC;DEABC; DAEBC; DABEC; DABCE5.5Consider the case in which turn equals 0 and P(1) sets blocked[1] totrue and then finds blocked[0] set to false. P(0) will then setblocked[0] to true, find turn = 0, and enter its critical section. P(1) will then assign 1 to turn and will also enter its critical section.C HAPTER 6C ONCURRENCY:D EADLOCK ANDS TARVATIONReview Questions6.2 Mutual exclusion. Only one process may use a resource at a time. Holdand wait. A process may hold allocated resources while awaitingassignment of others. No preemption. No resource can be forciblyremoved from a process holding it.6.3 The above three conditions, plus: Circular wait. A closed chain ofprocesses exists, such that each process holds at least one resourceneeded by the next process in the chain.Problems6.4 a. 0 0 0 00 7 5 06 6 2 22 0 0 20 3 2 0b. to d. Running the banker's algorithm, we see processes can finishin the order p1, p4, p5, p2, p3.e. Change available to (2,0,0,0) and p3's row of "still needs" to (6,5,2,2).Now p1, p4, p5 can finish, but with available now (4,6,9,8) neitherp2 nor p3's "still needs" can be satisfied. So it is not safe to grantp3's request.6.5 1. W = (2 1 0 0)2. Mark P3; W = (2 1 0 0) + (0 1 2 0) = (2 2 2 0)3. Mark P2; W = (2 2 2 0) + (2 0 0 1) = (4 2 2 1)4. Mark P1; no deadlock detectedReview Questions7.1 Relocation, protection, sharing, logical organization, physicalorganization.7.7 A logical address is a reference to a memory location independent ofthe current assignment of data to memory; a translation must be made to a physical address before the memory access can be achieved. A relative address is a particular example of logical address, in which the address is expressed as a location relative to some known point, usually the beginning of the program. A physical address, or absolute address, is an actual location in main memory.Problems7.6 a. The 40 M block fits into the second hole, with a starting address of80M. The 20M block fits into the first hole, with a starting address of 20M. The 10M block is placed at location 120M.40M 40M 60M 40M 40M 40M 30Mb. The three starting addresses are 230M, 20M, and 160M, for the 40M, 20M, and 10M blocks, respectively. 40M 60M 60M 40M 40M 40M 30Mc. The three starting addresses are 80M, 120M, and 160M, for the 40M,20M, and 10M blocks, respectively. C HAPTER 7M EMORY M ANAGEMENT7.12 a. The number of bytes in the logical address space is (216 pages) (210bytes/page) = 226 bytes. Therefore, 26 bits are required for the logical address.b. A frame is the same size as a page, 210 bytes.c. The number of frames in main memory is (232 bytes of mainmemory)/(210 bytes/frame) = 222 frames. So 22 bits is needed tospecify the frame.d. There is one entry for each page in the logical address space.Therefore there are 216 entries.e. In addition to the valid/invalid bit, 22 bits are needed to specify theframe location in main memory, for a total of 23 bits.30M40M40M60M40M40M40Md. The three starting addresses are 80M, 230M, and 360M, for the 40M,20M, and 10M blocks, respectively.C HAPTER 8V IRTUAL M EMORYReview Questions8.1 Simple paging: all the pages of a process must be in main memory forprocess to run, unless overlays are used. Virtual memory paging: not all pages of a process need be in main memory frames for the process to run.; pages may be read in as needed8.2 A phenomenon in virtual memory schemes, in which the processorspends most of its time swapping pieces rather than executinginstructions.Problems8.1 a. Split binary address into virtual page number and offset; use VPNas index into page table; extract page frame number; concatenateoffset to get physical memory addressb. (i) 1052 = 1024 + 28 maps to VPN 1 in PFN 7, (7 ⨯ 1024+28 = 7196)(ii) 2221 = 2 ⨯ 1024 + 173 maps to VPN 2, page fault(iii) 5499 = 5 ⨯ 1024 + 379 maps to VPN 5 in PFN 0, (0 ⨯ 1024+379 =379)8.4 a. PFN 3 since loaded longest ago at time 20b. PFN 1 since referenced longest ago at time 160c. Clear R in PFN 3 (oldest loaded), clear R in PFN 2 (next oldestloaded), victim PFN is 0 since R=0d. Replace the page in PFN 3 since VPN 3 (in PFN 3) is used furthestin the futuree. There are 6 faults, indicated by **4 0 0 0 *2*4 2*1**3 2VPN of pages in memory in LRU order 32143243434242241241243122Review Questions9.1 Long-term scheduling: The decision to add to the pool of processes tobe executed. Medium-term scheduling: The decision to add to thenumber of processes that are partially or fully in main memory.Short-term scheduling: The decision as to which available process willbe executed by the processor9.3 Turnaround time is the total time that a request spends in the system(waiting time plus service time. Response time is the elapsed timebetween the submission of a request until the response begins toappear as output.Problems9.1 Each square represents one time unit; the number in the square refersto the currently-running process.FCFS A A A B B B B B C C D D D D D E E E E E RR, q = 1 A B A B C A B C B D B D E D E D E D E E RR, q = 4 A A A B B B B C C B D D D D E E E E D E SPN A A A C C B B B B B D D D D D E E E E E SRT A A A C C B B B B B D D D D D E E E E E HRRN A A A B B B B B C C D D D D D E E E E E Feedback, q = 1 A B A C B C A B B D B D E D E D E D E EFeedback, q = 2i A B A A C B B C B B D D E D D E E D E EC HAPTER 9U NIPROCESSORS CHEDULINGA B C D ET a0 1 3 9 12T s 3 5 2 5 5 FCFS T f 3 8 10 15 20T r 3.00 7.00 7.00 6.00 8.00 6.20T r/T s 1.00 1.40 3.50 1.20 1.60 1.74 RR qT f 6.00 11.00 8.00 18.00 20.00= 1T r 6.00 10.00 5.00 9.00 8.00 7.60T r/T s 2.00 2.00 2.50 1.80 1.60 1.98RR qT f 3.00 10.00 9.00 19.00 20.00= 4T r 3.00 9.00 6.00 10.00 8.00 7.20T r/T s 1.00 1.80 3.00 2.00 1.60 1.88 SPN T f 3.00 10.00 5.00 15.00 20.00T r 3.00 9.00 2.00 6.00 8.00 5.60T r/T s 1.00 1.80 1.00 1.20 1.60 1.32SRT T f 3.00 10.00 5.00 15.00 20.00T r 3.00 9.00 2.00 6.00 8.00 5.60T r/T s 1.00 1.80 1.00 1.20 1.60 1.32 HRRT f 3.00 8.00 10.00 15.00 20.00NT r 3.00 7.00 7.00 6.00 8.00 6.20T r/T s 1.00 1.40 3.50 1.20 1.60 1.74FB qT f7.00 11.00 6.00 18.00 20.00= 1T r7.00 10.00 3.00 9.00 8.00 7.40T r/T s 2.33 2.00 1.50 1.80 1.60 1.85 FB T f 4.00 10.00 8.00 18.00 20.00q = 2i T r 4.00 9.00 5.00 9.00 8.00 7.00 T r/T s 1.33 1.80 2.50 1.80 1.60 1.819.16 a. Sequence with which processes will get 1 min of processor time:1 2 3 4 5 Elapsed timeA A A A A A A A A A A A A A BBBBBBBBCCDDDDDEEEEEEEEEEE1015192327303336384042434445The turnaround time for each process:A = 45 min,B = 35 min,C = 13 min,D = 26 min,E = 42 minThe average turnaround time is = (45+35+13+26+42) / 5 = 32.2 min b.Priority Job Turnaround Time3 4 6 7 9 BEACD99 + 12 = 2121 + 15 = 3636 + 3 = 3939 + 6 = 45The average turnaround time is: (9+21+36+39+45) / 5 = 30 min c.Job Turnaround TimeA B C D E 1515 + 9 = 24 24 + 3 = 27 27 + 6 = 33 33 + 12 = 45The average turnaround time is: (15+24+27+33+45) / 5 = 28.8 min d.RunningTimeJob Turnaround Time6 9 12 15 DBEA3 + 6 = 99 + 9 = 1818 + 12 = 3030 + 15 = 45The average turnaround time is: (3+9+18+30+45) / 5 = 21 minC HAPTER 10M ULTIPROCESSOR AND R EAL-T IMES CHEDULINGReview Questions10.1 Fine: Parallelism inherent in a single instruction stream. Medium: Parallelprocessing or multitasking within a single application. Coarse:Multiprocessing of concurrent processes in a multiprogrammingenvironment. Very Coarse: Distributed processing across network nodes toform a single computing environment. Independent: Multiple unrelatedprocesses.10.4 A hard real-time task is one that must meet its deadline; otherwise it willcause undesirable damage or a fatal error to the system. A soft real-timetask has an associated deadline that is desirable but not mandatory; it stillmakes sense to schedule and complete the task even if it has passed itsdeadline.Problems10.1 For fixed priority, we do the case in which the priority is A, B, C. Eachsquare represents five time units; the letter in the square refers to thecurrently-running process. The first row is fixed priority; the secondrow is earliest deadline scheduling using completion deadlines.A AB B A AC C A A B B A A C C A AA AB B AC C A C A A B B A A C C C A AFor fixed priority scheduling, process C always misses its deadline.10.4normal executionexecution in critical sectionT 1T 2T 3s locked by T 3s unlockeds locked by T 1Once T 3 enters its critical section, it is assigned a priority higher than T1. When T3 leaves its critical section, it is preempted by T 1.C HAPTER 11I/O M ANAGEMENT AND D ISK S CHEDULING Review Questions11.1 Programmed I/O: The processor issues an I/O command, on behalf of aprocess, to an I/O module; that process then busy-waits for theoperation to be completed before proceeding. Interrupt-driven I/O:The processor issues an I/O command on behalf of a process,continues to execute subsequent instructions, and is interrupted by the I/O module when the latter has completed its work. The subsequent instructions may be in the same process, if it is not necessary for that process to wait for the completion of the I/O. Otherwise, the process is suspended pending the interrupt and other work is performed. Direct memory access (DMA): A DMA module controls the exchange of data between main memory and an I/O module. The processor sends arequest for the transfer of a block of data to the DMA module and is interrupted only after the entire block has been transferred.11.5 Seek time, rotational delay, access time.Problems11.1 If the calculation time exactly equals the I/O time (which is the mostfavorable situation), both the processor and the peripheral devicerunning simultaneously will take half as long as if they ran separately.Formally, let C be the calculation time for the entire program and let T be the total I/O time required. Then the best possible running timewith buffering is max(C, T), while the running time without buffering is C + T; and of course ((C + T)/2) ≤ max(C, T) ≤ (C + T). Source:[KNUT97].11.3 Disk head is initially moving in the direction of decreasing tracknumber:FIFO SSTF SCAN C-SCANNext track accessed Numberof trackstraversedNexttrackaccessedNumberof trackstraversedNexttrackaccessedNumberof trackstraversedNexttrackaccessedNumberof trackstraversed27 73 110 10 64 36 64 36129 102 120 10 41 23 41 23 110 19 129 9 27 14 27 14 186 76 147 18 10 17 10 17 147 39 186 39 110 100 186 17641 106 64 122 120 10 147 3910 31 41 23 129 9 129 1864 54 27 14 147 18 120 9120 56 10 17 186 39 110 10 Average 61.8 Average 29.1 Average 29.6 Average 38If the disk head is initially moving in the direction of increasing tracknumber, only the SCAN and C-SCAN results change:SCAN C-SCANNext track accessed Numberof trackstraversedNexttrackaccessedNumberof trackstraversed110 10 110 10120 10 120 10129 9 129 9147 18 147 18186 39 186 3964 122 10 17641 23 27 1727 14 41 1410 17 64 23 Average 29.1 Average 35.1Review Questions12.1 A field is the basic element of data containing a single value. A recordis a collection of related fields that can be treated as a unit by some application program.12.5 Pile: Data are collected in the order in which they arrive. Each recordconsists of one burst of data. Sequential file: A fixed format is used for records. All records are of the same length, consisting of the same number of fixed-length fields in a particular order. Because the length and position of each field is known, only the values of fields need to be stored; the field name and length for each field are attributes of the file structure. Indexed sequential file: The indexed sequential file maintains the key characteristic of the sequential file: records are organized in sequence based on a key field. Two features are added; an index to the file to support random access, and an overflow file. The index provides a lookup capability to reach quickly the vicinity of a desired record. The overflow file is similar to the log file used with a sequential file, but is integrated so that records in the overflow file are located by following a pointer from their predecessor record. Indexed file: Records are accessed only through their indexes. The result is that there is now no restriction on the placement of records as long as a pointer in at least one index refers to that record. Furthermore,variable-length records can be employed. Direct, or hashed, file: The direct file makes use of hashing on the key value.Problems12.1 Fixed blocking: F = largest integer B RWhen records of variable length are packed into blocks, data formarking the record boundaries within the block has to be added to separate the records. When spanned records bridge block boundaries, some reference to the successor block is also needed. One possibility is a length indicator preceding each record. Another possibility is a special separator marker between records. In any case, we can assume that each record requires a marker, and we assume that the size of a marker is about equal to the size of a block pointer [WEID87]. For spanned blocking, a block pointer of size P to its successor block may C HAPTER 12F ILE M ANAGEMENTbe included in each block, so that the pieces of a spanned record can easily be retrieved. Then we haveVariable-length spanned blocking: F=B-P R+PWith unspanned variable-length blocking, an average of R/2 will be wasted because of the fitting problem, but no successor pointer is required:Variable-length unspanned blocking: F=B-R2 R+P12.3 a. Indexedb. Indexed sequentialc. Hashed or indexed。
操作系统精髓与设计原理课后答案
操作系统精髓与设计原理课后答案第1章计算机系统概述1.1 列出并简要地定义计算机的四个主要组成部分。
主存储器，存储数据和程序；算术逻辑单元，能处理二进制数据；控制单元，解读存储器中的指令并且使他们得到执行；输入/输出设备，由控制单元管理。
1.2 定义处理器寄存器的两种主要类别。
用户可见寄存器：优先使用这些寄存器，可以使机器语言或者汇编语言的程序员减少对主存储器的访问次数。
对高级语言而言，由优化编译器负责决定把哪些变量应该分配给主存储器。
一些高级语言，如C语言，允许程序言建议编译器把哪些变量保存在寄存器中。
控制和状态寄存器：用以控制处理器的操作，且主要被具有特权的操作系统例程使用，以控制程序的执行。
1.3 一般而言，一条机器指令能指定的四种不同操作是什么？处理器－寄存器：数据可以从处理器传送到存储器，或者从存储器传送到处理器。
处理器－I/O：通过处理器和I/O模块间的数据传送，数据可以输出到外部设备，或者从外部设备输入数据。
数据处理：处理器可以执行很多关于数据的算术操作或逻辑操作。
控制：某些指令可以改变执行顺序。
1.4 什么是中断？中断：其他模块（I/O，存储器）中断处理器正常处理过程的机制。
1.5 多中断的处理方式是什么？处理多中断有两种方法。
第一种方法是当正在处理一个中断时，禁止再发生中断。
第二种方法是定义中断优先级，允许高优先级的中断打断低优先级的中断处理器的运行。
1.6 内存层次的各个元素间的特征是什么？存储器的三个重要特性是：价格，容量和访问时间。
1.7 什么是高速缓冲存储器？高速缓冲存储器是比主存小而快的存储器，用以协调主存跟处理器，作为最近储存地址的缓冲区。
1.8 列出并简要地定义I/O操作的三种技术。
可编程I/O：当处理器正在执行程序并遇到与I/O相关的指令时，它给相应的I/O模块发布命令（用以执行这个指令）；在进一步的动作之前，处理器处于繁忙的等待中，直到该操作已经完成。
中断驱动I/O：当处理器正在执行程序并遇到与I/O相关的指令时，它给相应的I/O模块发布命令，并继续执行后续指令，直到后者完成，它将被I/O模块中断。
操作系统 精髓与设计原理(第五版))
第一章：计算机系统概述计算机系统基本组成I．处理器：控制计算机的操作，执行数据处理功能。
当只有一个处理器时，它通常指中央处理器（CPU）。
II. 主存储器：存储数据和程序。
iii．输入/输出模块：在计算机和外部环境之间移动数据。
iv．系统总线：为处理器、主存储器和输入输出模块提供通信的设施。
什么是中断？中断是指计算机的处理机用来处理外来请求或部错误的一种机制，该机制软硬件结合，使得计算机的处理机能够暂停当前指令系列的执行而转向请求指令系列的执行。
1.将计算机的处理机正在执行的指令系列称为当前指令系列，当前指令系列通常是用户程序。
2.将计算机为处理各类突发（非预期）事件请求（I/O请求,时钟请求，程序错误，硬件错误）而有待执行的指令系列称为请求指令系列，通常称为中断处理程序，是操作系统的一部分。
3.请求指令系列执行期间，可以被其它事件中断（在允许多重中断的情况下）。
4.执行请求指令系列完毕后，可以返回被暂停的原始指令系列，也可以不返回（在多道程序设计环境中）。
5.中断处理程序与社会事务中的应急事件的预案类似。
中断处理中断的发生激活了很多事情，包括处理器硬件中的事件及软件中的事件。
1.设备给处理器发出一个中断信号。
2.处理器在响应中断前结束指令系列的执行。
3.处理器对中断进行测定，确定存在未响应的中断，并给提交中断的设备发送确认信号，确认信号允许该设备取消它的中断信号。
4.处理器需要把处理权转移到中断程序中去做准备。
首先，需要保存从中断点恢复当前程序所需要的信息，要求的最少信息包括程序状态字（PSW）和保存在程序计数器中的下一条执行的指令地址，它们被压入系统控制栈中（参见附录1B）。
5.处理器把响应此中断的中断处理器入口地址装入程序的计数器中。
6.在这一点，与被中断程序相关的程序计数器和PSW被保存到系统栈中。
此外，还有一些其他信息被当作正在执行程序的状态的一部分。
7.中断处理器现在可以开始处理中断，其中包括检查与I/O操作相关的信息或其他引起中断的事件，还可能包括给I/O设备发送附加命令或应答。
《操作系统精髓与设计原理·第五版》习题答案
第1章计算机系统概述1.1、图1.3中的理想机器还有两条I/O指令：0011 = 从I/O中载入AC0111 = 把AC保存到I/O中在这种情况下，12位地址标识一个特殊的外部设备。
请给出以下程序的执行过程（按照图1.4的格式）：1.从设备5中载入AC。
2.加上存储器单元940的内容。
3.把AC保存到设备6中。
假设从设备5中取到的下一个值为3940单元中的值为2。
答案：存储器（16进制内容）：300：3005；301：5940；302：7006步骤1：3005－>IR；步骤2：3－>AC步骤3：5940－>IR；步骤4：3＋2＝5－>AC步骤5：7006－>IR：步骤6：AC－>设备61.2、本章中用6步来描述图1.4中的程序执行情况，请使用MAR和MBR扩充这个描述。
答案：1. a. PC中包含第一条指令的地址300，该指令的内容被送入MAR中。
b. 地址为300的指令的内容（值为十六进制数1940）被送入MBR，并且PC增1。
这两个步骤是并行完成的。
c. MBR中的值被送入指令寄存器IR中。
2. a. 指令寄存器IR中的地址部分（940）被送入MAR中。
b. 地址940中的值被送入MBR中。
c. MBR中的值被送入AC中。
3. a. PC中的值（301）被送入MAR中。
b. 地址为301的指令的内容（值为十六进制数5941）被送入MBR，并且PC增1。
c. MBR中的值被送入指令寄存器IR中。
4. a. 指令寄存器IR中的地址部分（941）被送入MAR中。
b. 地址941中的值被送入MBR中。
c. AC中以前的内容和地址为941的存储单元中的内容相加，结果保存到AC中。
5. a. PC中的值（302）被送入MAR中。
b. 地址为302的指令的内容（值为十六进制数2941）被送入MBR，并且PC增1。
c. MBR中的值被送入指令寄存器IR中。
6. a. 指令寄存器IR中的地址部分（941）被送入MAR中。
操作系统一精髓与设计原理第五版选择题与答案英文版第一到第十一章.doc
第一章The general role of an operating system is to:da. None of the aboveb. Man age files for application programsc. Act as an interface between various computersd. Provide a set of services to system users /Information that must be saved prior to the processor transferring control to the interrupt handler routine includes:ba. None of the aboveb. Processor Status Word (PSW) & Location of next instructionc. Processor Status Word (PSW)d. Processor Status Word (PSW) & Con tents of processor registersOne accepted method of dealing with multiple interrupts is to:选择一个答案aa. Define priorities for the interrupts Jb. None of the abovec. Disable all interrupts except those of highest priorityd. Service them in round-robin fashionIn a uniprocessor system, multiprogramming increases processor efficiency by:选择一个答案da. Increasing processor speedb. Eliminating all idle processor cyclesc. All of the aboved. Taking advantage of time wasted by long wait interrupt handling 、/As one proceeds down the memory hierarchy (i.e., from in board memory to offline storage), the following condition(s) apply: c选择一个答案a. Decreasing capacityb. In creasing cost per bitc. In creasing access timed. All of the aboveSmall, fast memory located between the processor and main memory is called选择一个答案ba. None of the aboveb. Cache memory /c. WORM memoryd. CD-RW memoryWhen a new block of data is written into cache memory, the following determines which cache location the block will occupy:选择一个答案aa. None of the above/b. Write policyc. Cache sized. Block sizeThe four main structural elements of a computer system are: 选择一个答案ba. Processor, Registers, I/O Modules & Main Memoryb. Processor, Main Memory, I/O Modules & System Bus、、(c. None of the aboved. Processor, Registers, Main Memory & System BusThe two basic types of processor registers are:选择一个答案aa. User-visible and Control/Status registers/b. User-visible and user-invisible registersc. None of the aboved. Control and Status registersAddress registers may contain选择一个答案ca. Memory addresses of datab. Memory addresses of instructionsc. All of the above Jd. Partial memory addressesA Control/Status register that contains the address of the next instruction to be fetched is called the:选择一个答案ca. All of the aboveb. Program Status Word (PSW)c. Program Counter (PC) Jd. Instruction Register (IR)The two basic steps used by the processor in instruction processing are:选择一个答案ca. Instruction and Execute cyclesb. Fetch and Instruction cyclesc. Fetch and Execute cycles Jd. None of the aboveA fetched instruction is normally loaded into the:选择一个答案ca. Program Counter (PC)b. None of the abovec. Instruction Register (IR)d. Accumulator (AC)A common class of interrupts is选择一个答案da. Programb. I/Oc. Timerd. All of the above/When an external device becomes ready to be serviced by the processor, the device sends this type of signal to the processor:选择一个答案ba. None of the aboveb. Interrupt signal /c. Halt signald. Handler signal第二章A primary objective of an operating system is:选择一个答案aa. All of the above/b. Conveniencec. Ability to evolved. EfficiencyThe paging system in a memory management system provides for dynamic mapping between a virtual address used in a program and:选择一个答案aa. A real address in main memoryb. None of the abovec. A virtual address in main memoryd. A real address in a programRelative to information protection and security in computer systems, access control typically refers to:选择一个答案da. Proving that security mechanisms perform according to specificationb. None of the abovec. The flow of data within the systemd. Regulating user and process access to various aspects of the system / Acommon problem with full-featured operating systems, due to their sizeand difficulty of the tasks they address, is:选择一个答案da. Latent bugs that show up in the fieldb. Chronically late in deliveryc. Sub-par performaneed. All of the above、/A technique in which a process, executing an application, is divided into threads that can run concurrently is called:选择一个答案da. None of the aboveb. Symmetric multiprocessing (SMP)c. Multiprocessingd. Multithreading JWIN2K supports several types of user applications, including:选择一个答案ca. None of the aboveb. Linuxc. WIN32 /d. System 10Key to the success of Linux has been ifs character as a free software package available under the auspices of the:选择一个答案ca. None of the aboveb. Berkeley Software Distributionc. Free Software Foundation Jd. World Wide Web ConsortiumThe operating system provides many types of services to end-users, programmers and system designers, including:选择一个答案ba. Built-in user applicationsb. Error detection and responsec. All of the aboved. Relational database capabilities with the internal file systemThe operating system is unusual in ifs role as a control mechanism, in that:选择一个答案ca. None of the aboveb. It runs on a special processor, completely separated from the rest of thesystemc. It frequently relinquishes control of the system processor and must dependon the processor to regain control of the system Jd. It never relinquishes control of the system processorOperating systems must evolve over time because选择一个答案aa. New hardware is designed and implemented in the computer systemb. Hardware must be replaced when it failsd. Users will only purchase software that has a current copyright dateA major problem with early serial processing systems was:选择一个答案aa. Setup time ，b. In ability to get hardcopy outputc. All of the aboved. Lack of input devicesAn example of a hardware feature that is desirable in a batch-processing system is 选择一个答案aa. Privileged instructionsb. None of the abovec. A completely accessible memory aread. Large clock cyclesA computer hardware feature that is vital to the effective operation of a multiprogramming operating system is:选择一个答案ba. All of the aboveb. I/O interrupts and DMAc. Very large memoryd. Multiple processorsThe principle objective of a time sharing, multiprogramming system is toa. Maximize processor useb. Maximize response timec. None of the aboved. Provide exclusive access to hardwareWhich of the following major line of computer system development created problems in timing and synchronization that contributed to the development of the concept of the process?选择一个答案ca. Multiprogramming batch operation systemsb. Real time transaction systemsc. All of the above Jd. Time sharing systems第三章The behavior of a processor can be characterized by examining: 选择一个答案ba. Multiple process tracesb. The interleaving of the process tracesc. All of the aboved. A single process traceThe Process Image element that con tains the modifiable part of the user space is called the:a进程镜像=PCB+程序+STACK+可修改的DATAb. Process Control Blockc. System Stackd. User Program分数:7/7The processor execution mode that user programs typically execute in is referred to as: a选择一个答案a. User modeb. None of the abovec. Kernel moded. System modeOne step in the procedure for creating a new process involves:步骤：b选择一个答案a. Allocating space for the processb. All of the above Jc. Initializing the process control blockd. Assigning a unique identifierA process switch may occur when the system encounters an interrupt condition, such as that generated by a:进程切换：TRAP（异常）+系统调用+INTERRUPT选择一个答案用户级上下文 系统级上下文 寄存器上下文c. All of the aboved. Memory fault##操作系统仅仅是一组程序，并被处理器执行，是进程吗？如何控制它？OOO 3种方法：无进程的内核在用户进程中执行（有一组进程切换函数）常用的PC 就是这样的 基于进程的操作系统 In the Process Based 0/S: 基于进程的操作系统Major kernel functions are organized as separate functions选择一个答案ca. The User Process Image includes a kernel stackb. 0/S code and data are contained in the shared address space Xc. Major kernel functions are organized as separate functionsd. None of the aboveUNIX 进程描述:进程正文，进程数据 内核栈 程序计数器，处理器状态寄存器 In a typical UNIX system, the element of the process image that contains the processor status information is the:选择一个答案da.Trapb. System-level contextc. User-level contextd. Register context J分数：7/7The behavior of an individual process can be characterized by examining:选择一个答案aa. A single process trace Jb. Multiple process tracesc. The in terleaving of the process tracesd. All of the aboveThe basic Two-State Process Model defines two possible states for a process in relationship to the processor:a选择一个答案a. Running and Not Runningb. None of the abovec. Executing and Waitingd. Running and Executing分数：7/7There are a number of conditions that can lead to process termination, including: c选择一个答案a. Bounds violationb. Pare nt termi natio nc. All of the above Jd. Normal completionIn the Five-State Process Model, the following represents a valid state transition:选择一个答案ca. All of the aboveb. New -> Runningc. Running -> Blockedd. New -> BlockedIn a Process Model that implements two suspend states, a valid state transition is represented by: 选择一个答案ba. Running -> Ready/Suspendb. All of the abovec. Ready -> Ready/Suspendd. Ready/Suspend -> ReadyThe scheduling strategy where each process in the queue is given a certain amount of time, in turn, to execute and then returned to the queue, unless blocked is referred to as:选择一个答案aa. Round-Robin Jb. All of the abovec. Prioritizationd. LIFO分数:6/6A Memory Table is an O/S control structure that is used by the O/S to: 选择一个答案ba. Manage I/O devicesb. None of the above Jc. Manage processesd. Provide information about system files分数：6/6进程描述：1. 操作系统的控制结构：4个表：内存表，跟踪主存，辅存IO表文件表进程表2. 进程控制结构：PCB,进程映像。
(完整版)操作系统教程第5版课后答案解析
操作系统教程第5版课后答案费祥林、骆斌编著第一章操作系统概论习题一一、思考题1.简述现代计算机系统的组成及层次结构。
答：现代计算机系统由硬件和软件两个部分组成。
是硬件和软件相互交织形成的集合体，构成一个解决计算问题的工具。
硬件层提供基本可计算的资源，包括处理器、寄存器、内存、外存及I/O设备。
软件层由包括系统软件、支撑软件和应用软件。
其中系统软件是最靠近硬件的。
2、计算机系统的资源可分成哪几类？试举例说明。
答：包括两大类，硬件资源和信息资源。
硬件资源分为处理器、I/O设备、存储器等；信息资源分为程序和数据等。
3•什么是操作系统？操作系统在计算机系统中的主要作用是什么？答：操作系统是一组控制和管理计算机硬件和软件资源，合理地对各类作业进行调度，以及方便用户使用的程序的集合。
操作系统在计算机系统中主要起4个方面的作用。
(1)服务用户观点一—操作系统提供用户接口和公共服务程序(2)进程交互观点一—操作系统是进程执行的控制者和协调者(3)系统实现观点一—操作系统作为扩展机或虚拟机(4)资源管理观点一—操作系统作为资源的管理者和控制者4.操作系统如何实现计算与操作过程的自动化?答：大致可以把操作系统分为以下几类：批处理操作系统、分时操作系统、实时操作系统、网络操作系统和分布式操作系统。
其中批处理操作系统能按照用户预先规定好的步骤控制作业的执行，实现计算机操作的自动化。
又可分为批处理单道系统和批处理多道系统。
单道系统每次只有一个作业装入计算机系统的主存储器运行，多个作业可自动、顺序地被装入运行。
批处理多道系统则允许多个作业同时装入主存储器，中央处理器轮流地执行各个作业，各个作业可以同时使用各自所需的外围设备，这样可以充分利用计算机系统的资源，缩短作业时间，提高系统的吞吐率5 •操作系统要为用户提供哪些基本的和共性的服务？答：（1）创建程序和执行程序；（2）数据I/O和信息存取；（3）通信服务；（4）差错检测和处理。
操作系统精髓与设计原理
操作系统精髓与设计原理操作系统是计算机系统中最核心的软件之一，它承担着管理和控制计算机硬件资源的重要任务。
操作系统的设计原理直接影响着计算机系统的性能、稳定性和安全性。
本文将从操作系统的精髓和设计原理两个方面进行探讨，希望能够为读者提供一些深入的理解和启发。
首先，我们来谈谈操作系统的精髓。
操作系统的核心功能包括进程管理、内存管理、文件系统、设备管理和用户接口等。
其中，进程管理是操作系统的基础，它负责对进程的创建、调度、同步和通信进行管理，保证系统资源的有效利用和进程的正常运行。
内存管理则关乎着系统的性能和稳定性，它需要对内存空间进行分配、回收和保护，避免出现内存泄漏和内存溢出的情况。
文件系统则是操作系统与外部存储设备进行交互的接口，它需要对文件进行管理、存储和检索，保证数据的安全和完整性。
设备管理负责对计算机的硬件设备进行管理和控制，包括输入输出设备、网络设备等，它需要提供统一的接口和管理机制，使得应用程序能够方便地与硬件设备进行交互。
用户接口则是操作系统与用户进行交互的方式，它需要提供友好、直观的界面，使得用户能够方便地使用计算机系统。
其次，我们来探讨操作系统的设计原理。
操作系统的设计原理包括了并发、共享、虚拟和异步等几个重要概念。
并发是指系统中存在多个独立的活动，并且这些活动可能同时进行，操作系统需要提供合适的机制来管理这些并发活动，保证它们能够正确、有效地运行。
共享是指系统中的资源可以被多个活动共同使用，操作系统需要提供合适的机制来保证资源的公平分配和合理利用。
虚拟是指操作系统需要对硬件资源进行抽象和虚拟化，使得应用程序能够独立于硬件进行开发和运行。
异步是指系统中的活动是相互独立、不可预测的，操作系统需要提供合适的机制来处理这种不确定性，保证系统的可靠性和稳定性。
在操作系统的设计中，需要考虑到这些原理，并且合理地应用它们，以满足系统的性能、稳定性和安全性要求。
同时，操作系统的设计也需要考虑到实际的应用场景和需求，保证系统能够满足用户的实际需求。
【英文原版】操作系统_精髓与设计原理_第6版 - Chapter14-new
Intruder Behavior: Hackers
Intruder Behavior: Criminal Enterprise
Intruder Behavior: Internal Threat
Roadmap
• • • • • • Computer Security Concepts Threats, Attacks, and Assets Intruders Malicious Software Overview Viruses, Worms, and Bots Rootkits
– Authenticity – Accountability
Roadmap
• • • • • • Computer Security Concepts Threats, Attacks, and Assets Intruders Malicious Software Overview Viruses, Worms, and Bots Rootkits
Malware
• General term for any Malicious softWare
– Software designed to cause damage – Or use up the resources of a target computer.
• Some malware is parasitic
Trojan Horse
• Useful program that contains hidden code that when invoked performs some unwanted or harmful function • Can be used to accomplish functions indirectly that an unauthorized user could not accomplish directly
操作系统—精髓与设计原理英文原版Ch虚拟内存
Management of virtual memory
VS
Dividing the memory into separate sections, each section assigned to a specific process or task. This allows each process to have its own dedicated memory space, preventing conflicts and ensuring secure operation.
Page faults
When a process tries to access a page that is not currently loaded into physical memory, a page fault occurs, and the OS swaps in the required page from disk.
Paging
Improves memory management by allowing the system to allocate memory in small, efficient chunks. It also allows for better memory utilization as unused pages can be freed up for other processes.
Page replacement algorithm：Page replacement algorithms are used in virtual memory management to determine which page frames to allocate to a process and which ones to swap out when the system runs out of physical memory. The most common page replacement algorithms are the least recently used (LRU) algorithm and the first-in, first-out (FIFO) algorithm.
操作系统操作精髓与设计原理习题解答
Computer System Overview ......................................................................5 Operating System Overview ....................................................................11 Process Description and Control .............................................................14 Threads, SMP, and Microkernels.............................................................18 Concurrency: Mutual Exclusion and Synchronization.........................21 Concurrency: Deadlock and Starvation..................................................30 Memory Management ...............................................................................38 Virtual Memory..........................................................................................43 Uniprocessor Scheduling ..........................................................................51 Multiprocessor and Real-Time Scheduling............................................62 I/O Management and Disk Scheduling..................................................65 File Management........................................................................................71 Networking .................................................................................................74 Distributed Processing, Client/Server, and Clusters............................76 Distributed Process Management............................................................79 Security ........................................................................................................82
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Distributed Processing Distributed Processing, Client/Server, and Clusters,Chapter13Chapter 131Client/Server ComputingClient/Server Computing •Client machines are generally single-user PCs Cli t hi ll i l PC or workstations that provide a highly user-friendly interface to the end userf i dl i t f t th d•Each server provides a set of shared services to the clientsy•The server enables many clients to share access to the same database and enables the use of a high-performance computer system tog p p y manage the database2Client/Server Terminology Client/Server TerminologyApplications Programming Interface (API)•Applications Programming Interface(API)– A set of function and call programs that allow clients and servers to intercommunicate•Client– A networked information requester, usually a PC or workstation, that canA k d i f i ll PC k i hquery database and/or other information from a server•Middleware,,p y – A set of drivers, APIs, or other software that improves connectivity betweena client application and a server•Relational Database– A database in which information access is limited to the selection of rows that satisfy all search criteriathat satisfy all search criteria•Server– A computer, usually a high-powered workstation, a minicomputer, or a mainframe, that houses information for manipulation by networked clients •Structured Query Language (SQL)– A language developed by IBM and standardized by ANSI for addressing, creating, updating, or querying relational databases34Client/Server Applications Client/Server Applications •Basic software is an operating system B i ft i ti trunning on the hardware platform •Platforms and the operating systems ofclient and server may differ•These lower-level differences areirrelevant as long as a client and server irrelevant as long as a client and servershare the same communicationsprotocols and support the same protocols and support the same applications56Client/Server Applications Client/Server Applications •Bulk of applications software executes B lk f li i fon the server•Application logic is located at the client •Presentation services in the clientP t ti i i th li t7Database ApplicationsDatabase Applications •The server is a database serverTh i d b•Interaction between client and server is in the form of transactions–the client makes a database request andthe client makes a database request andreceives a database response•Server is responsible for maintaining the S i ibl f i i i h database89Client/Server Database Usage Client/Server Database Usage10Client/Server Database Usage Client/Server Database Usage11Applications•Host-based processingH b d i–Not true client/server computing–Traditional mainframe environment12Applications•Server-based processingS b d i–Server does all the processing–Client provides a graphical user interface13Applications•Client-based processingCli b d i–All application processing done at the client –Data validation routines and other databaselogic functions are done at the serverog c u c o s e do e e se ve14Applications •Cooperative processingC i i–Application processing is performed in anoptimized fashionCo p e o se up d–Complex to set up and maintain15Three-Tier Client/ServerArchitecture •Application software distributed among A li ti ft di t ib t dthree types of machines–User machine•Thin client–Middle-tier server•Gateway•Convert protocols•Merge/integrate results from different datasources–Backend server1617File Cache ConsistencyFile Cache Consistency •File caches hold recently accessed file Fil h h ld l d fil records•Caches are consistent when they contain exact copies for remote dataexact copies for remote data•File-locking prevents simultaneous access to a file1819Middleware•Set of tools that provide a uniformS f l h id ifmeans and style of access to system resources across all platforms •Enable programmers to buildEnable programmers to build applications that look and feel the same •Enable programmers to use the same method to access data202122Middleware Mechanisms Middleware Mechanisms23Middleware Mechanisms Middleware Mechanisms24Middleware Mechanisms Middleware Mechanisms25Distributed Message Passing Distributed Message Passing •Message passed used to communicate M d d i among processes•Send and receive messages as used in a single system ORsingle system OR•Remote procedure calls26Basic Message-PassingPrimitives27Reliability VersusUnreliability •Reliable message-passing guarantees R li bl idelivery if possible–Not necessary to let the sending processknow that the message was deliveredg•Send the message out into thecommunication network without communication network withoutreporting success or failure–Reduces complexity and overhead28Blocking Versus Nonblocking Blocking Versus Nonblocking•Nonblocking–Process is not suspended as a result of issuing aSend or ReceiveSend or Receive–Efficient and flexible–Difficult to debug g•BlockingSend does not return control to the sending process –Send does not return control to the sending processuntil the message has been transmitted–OR does not return control until anacknowledgment is receivedk l d i i d–Receive does not return until a message has beenplaced in the allocated bufferplaced in the allocated buffer29Remote Procedure CallsRemote Procedure Calls •Allow programs on different machines All diff hito interact using simple procedurecall/return semantics•Widely acceptedWidely accepted•Standardized–Client and server modules can be movedamong computers and operating systemseasily3031Client/Server BindingClient/Server Binding •Binding specifies the relationshipBi di ifi th l ti hi between remote procedure and calling program•Nonpersistent binding–Logical connection established duringremote procedure call•Persistent bindingConnection is sustained after the procedure –Connection is sustained after the procedurereturns32Synchronous versusAsynchronous •Synchronous RPCS h RPC–Behaves much like a subroutine call •Asynchronous RPC–Does not block the callerDoes not block the caller–Enable a client execution to proceed locallyi ll l i h i iin parallel with server invocation33Object-Oriented Mechanisms Object Oriented Mechanisms •Clients and servers ship messages back and Cli t d hi b k d forth between objects• A client sends a request to an object brokerpp p j•The broker calls the appropriate object and passes along any relevant dataMicrosoft s Component Object Model (COM)•Microsoft’s Component Object Model(COM)•Common Object Request Broker Architecture (CORBA)34Clusters •Alternative to symmetricAl i imultiprocessing (SMP)•Group of interconnected, wholecomputers working together as a unified computers working together as a unifiedcomputing resource–Illusion is one machine–System can run on its own35Clustering MethodDescription Benefits Limitations Passive Standby A secondary serverEasy to implement High cost because the secondary Passive Standby A secondary server takes over in caseof primary serverfailure.Easy to implement.High cost because the secondary server is unavailable for other processing tasks.Active Secondary The secondaryserver is also usedfor processingtasks.Reduced cost because secondary servers can be used for processing.Increased complexity.Separate Servers Separate servers have their owndisks. Data iscontinuously copied High availability.High network and server overheaddue to copying operations.continuously copiedfrom primary tosecondary server.Servers Connected to Di k Servers are cabledt th di kReduced network and h d d Usually requires disk mirroring RAID t h l t t Disks to the same disks, but each serverowns its disks. Ifone server fails,it di k t kserver overhead due to elimination of copying operations.or RAID technology to compensate for risk of disk failure.its disks are taken over by the otherserver.Servers Share Disks Multiple serversLow network and Requires lock manager software. 36simultaneouslyshare access todisks.server overhead. Reduced risk of downtime caused bydisk ually used with disk mirroring or RAID technology.Clusters•Separate serverS–Each computer is a separate server–No shared disks–Need management or scheduling softwareNeed management or scheduling software –Data must be constantly copied amongsystems so each is currents stems so each is c rrent37Cluster Configurations Cluster Configurations38Clusters•Shared nothingSh d hi–Reduces communication overhead–Disks partitioned into volumes–Each volume owned by a computerEach volume owned by a computer–If computer fails another computer getsownership of the volumeo nership of the ol me39Cluster Configurations Cluster Configurations40Clusters•Shared diskSh d di k–Multiple computers share the same disks atthe same time–Each computer has access to all of thec co pu e s ccess o o evolumes on all of the disks41Issues•Failure managementF il–Highly available cluster offers a highprobability that al resources will be inservice•No guarantee about the state of partiallyexecuted transactions if failure occurs –Fault-tolerant cluster ensures that allresources are always availabley42Issues•Load balancingL d b l i–When new computer added to the cluster,the load-balancing facility shouldautomatically include this computer inscheduling applications •Parallelizing Computation Parallelizing Computation–Parallelizing compiler–Parallelized applicationP ll li d li i–Parametric computing43Architecture •Cluster middleware services andCl iddl i d functions–Single entry pointSingle file hierarchy–Single file hierarchy–Single control point–Single virtual networkingSi l i l ki–Single memory space–Single job-management system44Architecture •Cluster middleware services andCl iddl i d functions–Single user interfaceSingle I/O space–Single I/O space–Single process space–CheckpointingCh k i i–Process migration45Cluster Computer Architecture Cluster Computer Architecture46Clusters Compared to SMP Clusters Compared to SMP •SMP is easier to manage and configure SMP i i t d fi•SMP takes up less space and draws less power•SMP products are well established and S p oduc s e we es b s ed d stable•Clusters are better for incremental and Clusters are better for incremental and absolute scalabilityCl t i i t f •Clusters are superior in terms of availability47Windows Cluster Service Windows Cluster Service •Cluster ServiceCl t S i–Collection of software on each node that managesall cluster-specific activityll l t ifi ti it•Resource–Item managed by the cluster service•Online–Online at node when it is providing service on thatspecific node•Groupg g–Collection of resources managed as a single unit4849Sun ClusterSun Cluster•Major componentsM j–Object and communication support–Process management–Networking–Global distributed file system50。