操作系统选择题库答案及详解

Question1Concurrency plays a major part in which of the following specific contexts:选择一个答案a. Multiple applicationsb. All of the above √c. Structured applicationsd. O/S structureQuestion2In order to implement mutual exclusion on a critical resource for competing processes, only one program at a time should be allowed选择一个答案a. In the critical section of the program √b. None of the abovec. To Exhibit cooperationd. To perform message passingQuestion3The following requirement must be met by any facility or capability that is to provide support for mutual exclusion:选择一个答案a. All of the above √b. Only one process at a time can be allowed into a critical code sectionc. A process remains in its critical code section for a finite time onlyd. No assumptions can be made about relative process speedsQuestion4Processes that are designed to be able to pass execution control back and forth between themselves are referred to as选择一个答案a. None of the aboveb. Threadsc. Coroutines √d. Busy waiting processesQuestion5Processes that are designed to be able to pass execution control back and forth between themselves are referred to as选择一个答案a. Coroutines √b. Threadsc. None of the aboved. Busy waiting processesQuestion6In a uniprocessor system, mutual exclusion can be guaranteed by选择一个答案a. Interleaving processesb. Disabling interrupts √c. Overlapping processesd. All of the aboveQuestion7A semaphore that does not specify the order in which processes are removed from the queue is called a选择一个答案a. Binary semaphoreb. Weak semaphore √c. None of the aboved. Strong semaphoreQuestion8The finite circular buffer is used to implement which of the following basic queuing strategies选择一个答案a. LIFOb. FILOc. FIFO √d. None of the aboveQuestion9A chief characteristic of a monitor is:选择一个答案a. A maximum of two processes may be executing in a monitor at a timeb. All of the abovec. Local data variables of the monitor are accessible by any procedure requesting use of the monitord. A process enters the monitor by invoking one of its procedures √Question10In synchronization involving message passing, the sender of a message can be选择一个答案a. Only blockingb. All of the abovec. Only non-blockingd. Either blocking or non-blocking √Question11In a system employing message passing, when a message is sent to a shared temporary data structure, this general approach is known as选择一个答案a. Direct addressingb. Blockingc. Indirect addressing √d. None of the aboveQuestion12In a system employing message passing, the typical message is divided into two primary sections 选择一个答案a. None of the above √b. Body and mailboxc. Destination ID and Source IDd. Header and mailboxQuestion13The Reader/Writer problem requires that certain conditions be satisfied, such as:选择一个答案a. Any number of readers may simultaneously read from the file √b. None of the abovec. Readers may read from the file while writers are writing to itd. Multiple writers may write to the file simultaneouslyAny number of readers may simultaneously read from the fileQuestion14A reason why the Producer/Consumer problem cannot be considered a special case of the Reader/Writer problem with a single writer (the producer) and a single reader (the consumer) is: 选择一个答案a. None of the aboveb. The Producer/Consumer problem doesn’t deal with concurrency issuesc. The producer and consumer must be both reader and writer √d. The consumer must perform writes while the reader performs readsQuestion15Examples of solutions to the concurrency problem that do not involve busy waiting are the following:选择一个答案a. None of the above √b. Semaphores and monitorsc. Producers and consumersd. Message passing and cachingQuestion16A basic echo procedure (that echoes a typed character to the screen) running on a multiprocessor system can produce erroneous output if选择一个答案a. Two processes deadlock while in the echo codeb. Access to the echo procedure is uns ynchronized √c. None of the aboved. Access to the echo procedure is synchronizedMultiple Choice Questions 6Question1The permanent blocking of a set of processes that either compete for system resources or communicate with each other is called:选择一个答案a. Starvationb. All of the abovec. Prioritizationd. Deadlock √死锁是一组竞争系统资源或互相通信的竞争间相互的"永久"阻塞Question2In deadlocked process recovery, selection criteria for choosing a particular process to abort or rollback includes designating the process with the:选择一个答案a. Least total resources allocated so farb. Lowest priorityc. All of the above √d. Most estimated time remaining中文P196 死锁检测后恢复过程对“牺牲”进程的选择Question3One approach to an integrated strategy for dealing with deadlocks involves the implementation of:选择一个答案a. Process rollbacksb. Virtual memoryc. Resource classes √d. None of the above综合死锁策略：资源分类Question4The Dining Philosopher’s Problem is a standard test case for evaluating approaches to implementing: 选择一个答案a. Synchronization √b. Starvationc. All of the aboved. Deadlock哲学家进餐问题是评价同步方法的一个测试标准Question5A software mechanism that informs a process of the occurrences of asynchronous events in UNIX are called:选择一个答案a. Pipesb. Messagesc. Signals √d. All of the above信号是用于通知发生一个同步事件的软件机制Question6Thread synchronization primitives supported by Solaris include:选择一个答案a. Condition variablesb. Semaphoresc. All of the above √d. Mutual exclusion (mutex) locks互斥锁、信号量、多读者单写者锁、条件变量Question7The family of synchronization objects implemented by W2K include:选择一个答案a. Mutex objectsb. Event objectsc. All of the above √d. Semaphore objects事件、互斥、信号量、可等待的计时器Question8All deadlocks involve conflicting needs for resources by:选择一个答案a. Three or more processesb. One or more processesc. None of the aboved. Two or more processes √两个或多个进程资源需求冲突Question9A resource that can be created and destroyed is called a:选择一个答案a. Reusable resourceb. Producible resourcec. Consumable resource √d. All of the above可重用资源 VS 可消费资源Question10An example of a consumable resource is the following:选择一个答案a. All of the aboveb. Main Memoryc. Messages √d. Printers可创建可销毁的信息资源Question11A condition of policy that must be present for a deadlock to be possible is:选择一个答案a. Mutual exclusionb. No preemptionc. All of the above √d. Hold and wait三个必要条件Question12A direct method of deadlock prevention is to prevent the occurrence of:选择一个答案a. Hold and waitb. All of the abovec. Circular wait √d. Mutual exclusion死锁预防的直接法Question13In the Resource Allocation Denial approach to Deadlock Avoidance, a safe state is defined as one in which:选择一个答案a. At least one potential process sequence does not result in a deadlock √b. None of the abovec. All potential process sequences do not result in a deadlock:d. Several potential process sequences do not result in a deadlock:一条安全道路便可Question14A conservative strategy for dealing with deadlocks that involves limiting access to resources and imposing restrictions on processes is called:选择一个答案a. None of the aboveb. Deadlock Prevention √c. Deadlock Detectiond. Deadlock Avoidance资源预防Multiple Choice Questions 7Question1The task of subdividing memory between the O/S and processes is performed automatically by the O/S and is called:选择一个答案a. All of the aboveb. Protectionc. Memory Management √d. Relocation内存管理Question2A reference to a memory location independent of the current assignment of data to memory is called a: 选择一个答案a. Absolute addressb. None of the abovec. Logical address √d. Relative address逻辑地址的定义Question3An actual location in main memory is called a:选择一个答案a. Relative addressb. Absolute address √c. Logical addressd. None of the above物理地址即绝对地址Question4The page table for each process maintains:选择一个答案a. None of the aboveb. The frame location for each page of the process √c. The physical memory location of the processd. The page location for each frame of the process页号对应帧号Question5In a system employing a paging scheme for memory management, wasted space is due to:选择一个答案a. Internal fragmentation √b. Pages and frames of different specified sizesc. None of the aboved. External fragmentation固定分区和分页都产生内部碎片Question6In a system employing a segmentation scheme for memory management, wasted space is due to: 选择一个答案a. Internal fragmentationb. External fragmentation √c. None of the aboved. Segments of different sizes动态分区和分段都产生外部碎片Question7In a system employing a segmentation scheme for memory management, a process is divided into: 选择一个答案a. A number of segments which must be of equal sizeb. None of the abovec. A number of segments which need not be of equal size √d. One segment per thread分段：多个大小不等的块Question8The concept of Memory Management satisfies certain system requirements, including:选择一个答案a. Relocationb. Physical organizationc. All of the above √d. Protection重定位、保护、共享、逻辑组织、物理组织Question9The practice in which a program and data are organized in such a way that various modules can be assigned the same region of memory is called:选择一个答案a. Sharingb. None of the abovec. Overlaying √d. Relocation覆盖Question10The concept of virtual memory is based on one or both of two basic techniques:选择一个答案a. Segmentation and paging √b. None of the abovec. Overlaying and relocationd. Segmentation and partitioning虚拟=>分段分页Question11A problem with the largely obsolete Fixed Partitioning memory management technique is that of:选择一个答案a. Inefficient use of memoryb. Internal fragmentationc. Allowing only a fixed number of Processesd. All of the above √Question12The problem of internal fragmentation can be lessened in systems employing a fixed-partition memory management scheme by using:选择一个答案a. Unequal size partitions √b. Random size partitionsc. Equal size partitionsd. None of the above分段解决内部碎片，但是会引入外部碎片Question13In the Dynamic Partitioning technique of memory management, the phenomenon that results in unused blocks of memory outside of existing partitions is called:选择一个答案a. Compactionb. Internal fragmentationc. None of the aboved. External fragmentation √动态分区外部碎片Question14In the Dynamic Partitioning technique of memory management, the placement algorithm that chooses the block that is closest in size to the request is called:选择一个答案a. All of the aboveb. Next-fitc. First-fitd. Best-fit √最佳适配，首次适配，邻近适配Question15In the Dynamic Partitioning technique of memory management, the placement algorithm that scans memory from the location of the last placement and chooses the next available block that large enough to satisfy the request is called:选择一个答案a. First-fitb. All of the abovec. Best-fitd. Next-fit √Multiple Choice Questions 8Question1The type of memory that allows for very effective multiprogramming and relieves the user of me mory size constraints is referred to as:选择一个答案a. Virtual memory √b. Real memoryc. Main memoryd. All of the aboveQuestion2The replacement policy that is impossible to implement because it would require the O/S to have perfect knowledge of future events is called the:选择一个答案a. Least recently used (LRU) policyb. Clock policyc. Optimal policy √d. None of the aboveQuestion3The replacement policy that chooses only among the resident pages of the process that generate d the page fault in selecting a page to replace is referred to as a:选择一个答案a. Local replacement policy √b. Variable replacement policyc. Global replacement policyd. None of the aboveQuestion4The concept associated with determining the number of processes that will be resident in mainmemory is referred to as:选择一个答案a. A cleaning policyb. Load Controlc. None of the aboved. The page fault frequency √Question5In SVR4 and Solaris systems, the memory management scheme that manages user processes and disk I/O is called the:选择一个答案a. Paging system √b. None of the abovec. Virtual memory managerd. Kernel memory allocatorQuestion6The multilevel memory management scheme implemented in Linux was designed to minimize lar ge page tables and directories in which of the following line of processors:选择一个答案a. 32-bit Pentium/X86 architectureb. 16-bit X86 architecturec. 64-bit Alpha architecture √d. None of the aboveQuestion7The Windows 2000 virtual memory manager can use page sizes ranging from:选择一个答案a. 64 KB to 4 GBb. None of the abovec. 4 KB to 64 KB √d. 4 GB to 4 TBQuestion8The situation where the processor spends most of its time swapping process pieces rather than e xecuting instructions is called:选择一个答案a. Pagingb. The Principle of Localityc. None of the aboved. Thrashing √Question9The situation that occurs when the desired page table entry is not found in the Translation Lookas ide Buffer (TLB) is called a:选择一个答案a. None of the aboveb. TLB hitc. TLB miss √d. Page faultQuestion10The real address of a word in memory is translated from the following portions of a virtual addres s:选择一个答案a. None of the aboveb. Frame number and offsetc. Page number and frame numberd. Page number and offset √Question11Segmentation has a number of advantages to the programmer over a non-segmented address sp ace, including:选择一个答案a. Sharing among processesb. Simplifying the handling of growing data structuresc. All of the above √d. ProtectionQuestion12In a combined paging/segmentation system, a user’s address space is broken up into a number of :选择一个答案a. Fixed-size pages, which are in turn broken down into variable-sized segmentsb. Segments or pages, at the discretion of the programmerc. Variable-sized Segments, which are in turn broken down into fixed-size pages √d. All of the aboveQuestion13Sharing is achieved in a segmentation system by:选择一个答案a. Having a common data area that all processes can shareb. Referencing a segment in the segment tables of more than one process √c. All of the aboved. Each process segment table having a reference to the dispatcher main memory area Question14A fundamental choice in the design of the memory-management portion of an O/S is:选择一个答案a. Whether or not to use virtual memory techniquesb. All of the above √c. Whether to use paging, segmentation of a combination of the twod. The algorithms employed for various aspects of memory managementQuestion15The fetch policy that exploits the characteristics of most secondary memory devices, such as disks , which have seek time and rotational latency is called:选择一个答案a. Swappingb. Demand pagingc. Prepaging √d. None of the aboveMultiple Choice Questions 9Question1The type of scheduling that involves the decision to add a process to those that are at least partia lly in main memory and therefore available for execution is referred to as:选择一个答案a. Medium-term scheduling √b. None of the abovec. Long-term schedulingd. I/O schedulingQuestion2One difficulty with the Shortest Process Next (SPN) scheduling technique is:选择一个答案a. All of the above √b. The lack of preemptionc. The need to know or estimate required processing times for each processd. The starvation of longer processesQuestion3One difficulty with the Shortest Remaining Time (SRT) scheduling technique is:选择一个答案a. The lack of preemptionb. The starvation of shorter processesc. The need to know or estimate required processing times for each process √d. All of the aboveQuestion4Which of the following scheduling policies require prior knowledge or estimation of process lengt h:选择一个答案a. Highest Response Ratio Next (HRRN)b. Shortest Remaining Time (SRT)c. Shortest Process Next (SPN)d. All of the above √Question5It is impossible to make definitive comparisons of various scheduling policies due to dependence on factors such as:选择一个答案a. The probability distribution of service times of the various processesb. The efficiency of the scheduling and context switching mechanismsc. All of the above √d. The nature of the I/O demand and performance of the I/O subsystemQuestion6The strategy that schedules processes based on their group affiliation is generally referred to as: 选择一个答案a. Fair share scheduling √b. All of the abovec. Simulation modelingd. Queuing analysis公平共享Question7The traditional UNIX scheduler divides processes into fixed bands of priority levels, with the highe st priority band being the:选择一个答案a. User process bandb. None of the abovec. File manipulation bandd. Swapper band √Question8The decision as to which job to admit to the system next can be based on which of the following c riteria:选择一个答案a. Priorityb. Simple FIFOc. I/O requirementsd. All of the above √Question9Typically, the swapping-in function for processes is based on the need to manage:选择一个答案a. Virtual memoryb. The degree of multiprogramming √c. None of the aboved. Process prioritiesQuestion10In terms of frequency of execution, the short-term scheduler is usually the one that executes:选择一个答案a. Least frequentlyb. None of the abovec. About the same as the other schedulersd. Most frequently √Question11Response time in an interactive system is an example of:选择一个答案a. System-oriented criteria for short-term scheduling policiesb. None of the abovec. User-oriented criteria for short-term scheduling policies √d. System-oriented criteria for long-term scheduling policiesQuestion12A typical way to overcome starvation of lower-priority processes in a priority-based scheduling sy stem is to:选择一个答案a. Round-robin cycling of processes in a priority queueb. All of the abovec. Change a process priority randomlyd. Change a process priority with its age √Question13Which of the following scheduling policies allow the O/S to interrupt the currently running proces s and move it to the Ready state?选择一个答案a. First-come-first-servedb. Non-Preemptivec. None of the aboved. Preemptive √Question14In terms of the queuing model, the total time that a process spends in a system (waiting time plu s service time) is called:选择一个答案a. None of the aboveb. Normalized turnaround time (TAT)c. Turnaround or residence time (TAT) √d. Finish time (FT)Question15In the Round Robin scheduling technique, the principle design issue is:选择一个答案a. Determining the fair distribution of time quanta to individual processesb. Determining the length of the time quantum √c. None of the aboved. Determining the method of cycling through a given set of processesMultiple Choice Questions 10Question1An example of the key differences that can exist across (and even in) classes of I/O devices is:选择一个答案a. Error conditionsb. Data ratec. Data representationd. All of the above √Question2The following disk scheduling policy is useful as a benchmark against which to evaluate other disk scheduling policies because it provides a worst-case scenario:选择一个答案a. Priority schedulingb. FIFO schedulingc. None of the aboved. Random scheduling √Question3The disk scheduling algorithm that implements two subqueues in a measure to avoid the proble m of “arm stickiness” is the:选择一个答案a. All of the aboveb. FSCAN policy √c. N-step-SCAN policyd. C-SCAN policyQuestion4Which of the following RAID levels implement some form of parity calculation to introduce redun dancy:选择一个答案a. RAID Level 4b. RAID Level 6c. All of the above √d. RAID Level 2Question5The disk cache replacement strategy that replaces the block that has experienced the fewest references is called:选择一个答案a. Least Referenced (LR)b. Least Frequently Used (LFU) √c. All of the aboved. Least Recently Used (LRU)Question6In a UNIX system, which of the following types of I/O devices make use of character queues:选择一个答案a. Communications lines √b. Tape drivec. All of the aboved. Disk driveQuestion7In a W2K system, the I/O manager module that includes lazy write and lazy commit services to im prove overall performance is the:选择一个答案a. Hardware device driversb. File system driversc. Cache manager √d. None of the aboveQuestion8The I/O technique where the processor busy waits for an I/O operation to complete is called:选择一个答案a. Direct memory access (DMA)b. Programmed I/O √c. Interrupt-driven I/Od. None of the aboveQuestion9The system configuration that includes an I/O module which is a separate processor with a specia lized instruction set can be referred to using the following terminology:选择一个答案a. Direct Memory Access (DMA)b. All of the above √c. I/O Channeld. I/O ProcessorQuestion10The bus configuration for DMA that provides no path other than the system bus between the DM A module(s) and I/O devices is:选择一个答案a. I/O busb. Single bus, detached DMA √c. Single bus, integrated DMA-I/Od. None of the aboveQuestion11The primary objective in designing the I/O facility of a computer system that deals with the desire to handle all I/O devices in a uniform manner is referred to as:选择一个答案a. Directory managementb. Generality √c. None of the aboved. EfficiencyQuestion12In a hierarchical structure for managing I/O on a secondary storage device that supports a file syst em, the layer that is closest to the hardware is the:选择一个答案a. Device I/O layerb. None of the above √c. Physical organization layerd. Directory management layerQuestion13An example of a block-oriented I/O device is:选择一个答案a. Modemb. All of the abovec. CD-ROM √d. PrinterQuestion14The scenario where multiple buffers are used in an attempt to alleviate the problem of absorbing rapid bursts of I/O is typically referred to as:选择一个答案a. None of the aboveb. Double bufferingc. Circular buffering √d. Single bufferingMultiple Choice Questions 11Question1A file is generally defined to be:选择一个答案a. All of the aboveb. A collection of related fieldsc. A basic element of datad. A collection of similar records √Question2Fixed file blocking experiences the following potential problem:选择一个答案a. External fragmentationb. None of the abovec. Internal fragmentation √d. Gaps due to hardware designQuestion3In which of the following file allocation methods is preallocation required:选择一个答案a. Indexedb. None of the abovec. Chainedd. Contiguous √Question4The technique of free disk space management that employs a pointer and length value of each fr ee portion is the:选择一个答案a. None of the above √b. Free block listc. Bit tablesd. IndexingQuestion5The data structure that maintains information on available disk space is called the:选择一个答案a. File Allocation Table (FAT)b. None of the abovec. Bit Tabled. Disk Allocation Table √Question6File allocation in a UNIX system has the following characteristics:选择一个答案a. Dynamic allocation using non-contiguous blocks with indexing √b. Preallocation using non-contiguous blocks without indexingc. None of the aboved. Dynamic allocation using contiguous blocks without indexingQuestion7In a W2K NTFS file system, the smallest physical storage unit on the disk (almost always 512 bytes ) is called a:选择一个答案a. Clusterb. Volumec. Sector √d. None of the aboveQuestion8The level of the file system architecture that enables users and applications to access file records i s called the:选择一个答案a. Logical I/O level √b. All of the abovec. Basic I/O supervisor leveld. Basic file system levelQuestion9Record access in a pile file can be conducted by:选择一个答案a. Key fieldb. All of the abovec. Exhaustive search √d. Partial indexQuestion10Sequential files are optimal in scenarios involving:选择一个答案a. Applications that require infrequent updatesb. All of the abovec. Applications that require frequent queriesd. Applications that require the processing of all records in the file √Question11Indexed sequential files similar to sequential files, but contain two added features:选择一个答案a. File index and overflow file √b. Hash function and an overflow filec. All of the aboved. Hash function and file indexQuestion12Direct or hashed files are often used where:选择一个答案a. Fixed length records are usedb. All of the above √c. Very rapid access is requiredd. Records are always accessed one at a timeQuestion13The file directory information element that holds information such as the identity of the creator o f the file is the:选择一个答案a. All of the aboveb. Address information elementc. Usage information element √d. Access control information elementQuestion14In a tree-structured directory, the series of directory names that culminates in a file name is refer red to as the:选择一个答案a. Pathname √b. Working directoryc. None of the aboved. Symbolic nameQuestion15Access rights on a file typically are considered to constitute a hierarchy, with each right implying t hose that:选择一个答案a. Precede it √b. Succeed itc. None of the aboved. Supercede it。