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Suppose we have the following page accesses: 1 2 3 4 2 3 4 1 2 1 1 3 1 4 and that there are three frames within our system. Using the FIFO replacement algorithm, what is the number of page faults for the given reference string?
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In the enhanced second chance algorithm, which of the following ordered pairs represents a page that would be the best choice for replacement?
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COP4610 Final Exam
| Question | Answer |
|---|---|
| Suppose we have the following page accesses: 1 2 3 4 2 3 4 1 2 1 1 3 1 4 and that there are three frames within our system. Using the FIFO replacement algorithm, what is the number of page faults for the given reference string? | 8 |
| In the enhanced second chance algorithm, which of the following ordered pairs represents a page that would be the best choice for replacement? | (0,0) |
| Which of the following statements is false with regard to Solaris memory management? | The speed at which pages are examined (the scanrate) is constant. |
| The ____ is the number of entries in the TLB multiplied by the page size. | TLB reach |
| In systems that support virtual memory, ____ | physical memory is separated from logical memory. |
| _____ occurs when a process spends more time paging than executing. | Thrasing |
| _____ is the algorithm implemented on most systems. | LRU |
| Belady's anomaly states that ____. | for some page replacement algorithms, the page-fault rate may increase as the number of allocated frames increases |
| Suppose we have the following page accesses: 1 2 3 4 2 3 4 1 2 1 1 3 1 4 and that there are three frames within our system. what will be the final configuration of the three frames following the execution of the given reference string | 3, 4, 2 |
| The vfork() system call in UNIX ____. | allows the child process to use the address space of the parent |
| Optimal page replacement ____. | is used mostly for comparison with other page-replacement schemes |
| Which of the following statements is false with regard to allocating kernel memory? | Because the kernel requests memory of varying sizes, some of which may be quite small, the system does not have to be concerned about wasting memory. |
| What size segment will be allocated for a 39 KB request on a system using the Buddy system for kernel memory allocation? | 64 KB |
| The _____ is an approximation of a program's locality. | working set |
| Given the reference string of page accesses: 1 2 3 4 2 3 4 1 2 1 1 3 1 4 and a system with three page frames, what is the final configuration of the three frames after the true LRU algorithm is applied? | 3, 1, 4 |
| Which of the following is a benefit of allowing a program that is only partially in memory to execute? | All of these answers are correct |
| ______ allows a portion of a virtual address space to be logically associated with a file. | Memory-mapping |
| The _____ allocation algorithm allocates available memory to each process according to its size. | proportional |
| ________ allows the parent and child processes to initially share the same pages, but when either process modifies a page, a copy of the shared page is created. | copy-on-write |
| A character-stream device ____. | transfers data a byte at a time |
| Which of the following is a principle that can improve the efficiency of I/O? | Move processing primitives into hardware |
| An interrupt priority scheme can be used to ____. | All answers are correct |
| DMA controllers ____. | can steal memory access cycles from the main CPU |
| A(n) ____ is a front-end processor that multiplexes the traffic from hundreds of remote terminals into one port on a large computer. | terminal concentrator |
| DMA controllers ____. | can steal memory access cycles from the main CPU |
| An interrupt priority scheme can be used to ____. | All answers are correct |
| Which of the following is a principle that can improve the efficiency of I/O? | Move processing primitives into hardware |
| A character-stream device ____. | transfers data a byte at a time |
| Consider a system crash on a log-structured file system. Which one of the following events must occur? | All transactions in the log must be completed. |
| A RAID structure ____. | is primarily used to ensure higher data reliability |
| _____ is a technique for managing bad blocks that maps a bad sector to a spare sector. | Sector sparing |
| onsider a disk queue 116, 22, 3, 11, 75, 185, 100, 87. Using the SCAN scheduling algorithm, what is the order that the requests are serviced, assuming the disk head is at cylinder 88 and moving upward through the cylinders? | 100 - 116 - 185 - 87 - 75 - 22 - 11 – 3 |
| Consider a disk queue holding requests to the following cylinders in the listed order: 116, 22, 3, 11, 75, 185, 100, 87. Using the SSTF scheduling algorithm, at cylinder 88 and moving upward through the cylinders? | 87 - 75 - 100 - 116 - 185 - 22 - 11 – 3 |
| Consider a disk queue holding requests to the following cylinders in the listed order: 116, 22, 3, 11, 75, 185, 100, 87. Using the FCFS scheduling algorithm, assuming the disk head is at cylinder 88 and moving upward through the cylinders? | 116 - 22 - 3 - 11 - 75 - 185 - 100 – 87 |
| Consider a disk queue holding requests to the following cylinders in the listed order: 116, 22, 3, 11, 75, 185, 100, 87. Using the C-SCAN scheduling algorithm, assuming the disk head is at cylinder 88 and moving upward through the cylinders? | 100 - 116 - 185 - 3 - 11 - 22 - 75 - 87 |
| Swap space management ____. | tries to provide the best throughput for the virtual memory system |
| On media that uses constant linear velocity, the ____. | density of bits per track is uniform |
| Which of the following statements is false? | Typically, entire processes are swapped into memory. |
| The re-recordable CD-RW and DVD-RW are examples of ____ disks. | phase-change |
| Which of the following disk head scheduling algorithms does not take into account the current position of the disk head? | FCFS |
| RAID level ____ is the most common parity RAID system. | 5 |
| Which RAID level is best for storing large volumes of data? | storage-area network |
| On media that uses constant linear velocity, the ____. | density of bits per track is uniform |
| The surface of a magnetic disk platter is divided into ____. | Tracks |
| What are the two components of positioning time? | seek time + rotational latency |
| The SSTF scheduling algorithm __ | services the request with the minimum seek time |
| Low-level formatting ____. | divides a disk into sections that the disk controller can read and write |
| Host-attached storage is ____. | accessed via local I/O ports |
| Order the following file system layers in order of lowest level to highest level. | 5,1,3,4,2 |
| ______ includes all of the file system structure, minus the actual contents of files. | Metadata |
| On UNIX systems, the data structure for maintaining information about a file is a(n) _____. | Inode |
| Which algorithm is considered reasonable for managing a buffer cache? | least-recently-used (LRU) |
| A contiguous chunk of disk blocks is known as a(n) _____. | extent |
| Which of the following is the simplest method for implementing a directory? | linear list |
| The mount protocol ____. | establishes the initial logical connection between a server and a client |
| NFS views a set of interconnected workstations as a set of ____. | independent machines with independent file systems |
| Which of the following allocation methods ensures that only one access is needed to get a disk block using direct access? | contiguous allocation |
| Which of the following statements regarding the WAFL file system is incorrect? | It provides little replication. |
| Transfers between memory and disk are performed a ____. | block at a time |
| How many disk accesses are necessary for direct access to byte 20680 assuming each disk block is 4 KB in size? | 5 |
| In the Linux VFS architecture, a(n) ____ object represents an individual file. | inode |
| Page caching ____. | uses virtual memory techniques to cache file data as pages as opposed to system-oriented blocks. |
| 6. The free-space list can be implemented using a bit vector approach. Which of the following is a drawback of this technique? | It is not feasible to keep the entire list in main memory for large disks. |
| A disk with free blocks 0,1,5,9,15 would be represented with what bit map? | 1100010001000001 |
| The file-allocation table (FAT) used in MS-DOS is an example of _____. | linked allocation |
| A _____ is a view of a file system before the last update took place. | snapshot |
| A volume control block ____. | contains information such as the number of blocks in a partition, size of the blocks, and free-block and FCB count and pointers |
| Consider a system crash on a log-structured file system. Which one of the following events must occur? | All transactions in the log must be completed. |
| A _____ is used on UNIX systems at the beginning of some files to roughly indicate the type of the file. | magic number |
| Which of the following is a key property of an file? | The file name may not be reused. |
| An acyclic-graph directory structure ____. | allows the sharing of subdirectories and files. |
| Suppose that the operating system uses two internal tables to keep track of open files. How many entries are in the per-process table of process A, the per-process table of process B, and the system-wide tables, respectively? | 2, 3, 3 |
| ______ is a secure, distributed naming mechanism. | Lightweight directory-access protocol (LDAP) |
| ________ is/are not considered a difficulty when considering file sharing. | Reliability |
| A(n) ____ file is a sequence of subroutines and functions | source |
| An exclusive lock ____. | behaves like a writer lock |
| A shared lock ____. | behaves like a reader lock |
| The path name /home/people/os-student/chap10.txt is an example of | an absolute path name |
| Which of the following is true of the direct-access method? | It allows programs to read and write records in no particular order. |
| The simplest file access method is ____. | sequential access |
| app.exe is an example of a(n) _____. | executable file |
| A(n) ____ file is a series of code sections that the loader can bring into memory and execute. | executable |
| A(n) ____ file is a sequence of bytes organized into blocks understandable by the system's linker. | object |
| A mount point is _____. | the location within the file structure where the file system is to be attached. |
| Which of the following is not considered a classification of users in connection with each file? | current user |
| In an environment where several processes may open the same file at the same time, ____. | the operating system typically uses two internal tables called the system-wide and per-process tables to keep track of open files |
| The UNIX file system uses which of the following consistency semantics? | Writes to an open file by a user are visible immediately to other users that have the file open at the same time. |
| Which of the following is true of the tree-structured directory structure? | It is the most common directory structure. |
| An address generated by a CPU is referred to as a ____. | logical address |
| With segmentation, a logical address consists of _____. | segment number and offset |
| A(n) ______ matches the process with each entry in the TLB. | address-space identifier |
| In a dynamically linked library, ____. | a stub is included in the image for each library-routine reference |
| Absolute code can be generated for ____. | compile-time binding |
| Given the logical address 0xAEF9 (in hexadecimal) with a page size of 256 bytes, what is the page number? | 0xAE |
| Given the logical address 0xAEF9 (in hexadecimal) with a page size of 256 bytes, what is the page offset? | 0xF9 |
| The _____ binding scheme facilitates swapping. | execution time |
| Which of the following data structures is appropriate for placing into its own segment? | All of the above |
| _____ is the dynamic storage-allocation algorithm which results in the smallest leftover hole in memory. | Best fit |
| _____ is the dynamic storage-allocation algorithm which results in the largest leftover hole in memory. | Worst fit |
| Suppose a program is operating with execution-time binding and the physical address generated is 300. The relocation register is set to 100. What is the corresponding logical address? | 200 |
| A(n) ____ page table has one page entry for each real page (or frame) of memory. | Inverted |
| Assume the value of the base and limit registers are 1200 and 350 respectively. Which of the following addresses is legal? | 1200 |
| Consider a logical address with a page size of 8 KB. How many bits must be used to represent the page offset in the logical address? | 13 |
| The roll out, roll in variant of swapping is used ____. | for priority-based scheduling algorithms |
| Consider a logical address with 18 bits used to represent an entry in a conventional page table. How many entries are in the conventional page table? | 262144 |
| Which of the following is true of compaction? | It is possible only if relocation is dynamic and done at execution time. |
| Assume a system has a TLB hit ratio of 90%. It requires 15 nanoseconds to access the TLB, and 85 nanoseconds to access main memory. What is the effective memory access time in nanoseconds for this system? | 108.5 |
| _____ is the method of binding instructions and data to memory performed by most general-purpose operating systems. | Execution time binding |
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