Rank the disk scheduling algorithms (FCFS, SSTF, SCAN, and C-SCAN) in terms of their fairness in servicing a continuous stream of disk requests; order them from the most fair to the least fair. Consider a general stream of random disk requests, not a particular workload. (Verify your answer with reasons) OSSTF, SCAN, C-SCAN, FCFS O None of these O FCFS, SSTF, SCAN, C-SCAN OSCAN, C-SCAN, SSTF, FCFS Let's say the reference string is 04142434 2404142434 and we have 3 frames. By using clock algorithm the fault rate is . O 0.3 O 0.2 O 0.4 O 0.6 0.5

Rank the disk scheduling algorithms (FCFS, SSTF, SCAN, and C-SCAN) in terms of their fairness in servicing a continuous stream of disk requests; order them from the most fair to the least fair. Consider a general stream of random disk requests, not a particular workload. (Verify your answer with reasons) OSSTF, SCAN, C-SCAN, FCFS O None of these O FCFS, SSTF, SCAN, C-SCAN OSCAN, C-SCAN, SSTF, FCFS Let's say the reference string is 04142434 2404142434 and we have 3 frames. By using clock algorithm the fault rate is . O 0.3 O 0.2 O 0.4 O 0.6 0.5

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Suppose we have a system with 50 active processes, P0, P1, ..., P49, some user processes, and some kernel processes. For simplicity, we are not concerned with threads in this question. Ready processes are scheduled to Run by some scheduler. The scheduling algorithm does not matter here. Suppose process P13 makes a disk_read() operating system call. Assume that completion of disk transfer is signaled by an interrupt from the disk controller. Trace as accurately as you can what happens in the CPU (not the disk) until process P13 has received its requested information from the disk. Hints: The question is about interrupt handlingI am looking for a trace of what processes run, why, and what they do.I am not looking for instruction-level explanations.I am not looking for a discussion of disk access, operation, or transfer.
Suppose we have a system with 50 active processes, P0, P1, ..., P49, some user processes, and some kernel processes. For simplicity, we are not concerned with threads in this question. Ready processes are scheduled to Run by some scheduler. The scheduling algorithm does not matter here. Suppose process P13 makes a disk_read() operating system call. Assume that the completion of disk transfer is signalled by an interrupt from the disk controller. Trace as accurately as you can what happens in the CPU (not the disk) until process P13 has received its requested information from the disk. Hints: The question is about interrupt handling I am looking for a trace of what processes run, why, and what they do. I am not looking for instruction-level explanations. I am not looking for a discussion of disk access, operation, or transfer.
Compare the main memory organization schemes of contiguous-memory allocation, pure segmentation, and pure paging with respect to the following issues: a. External fragmentation b. Internal fragmentation c. ability to share code across processes
The principal advantage is a savings in physical memory space. This occurs for two reasons: (1) a user page table can be paged in to memory only when it is needed. (2) The operating system can allocate user page tables dynamically, creating one only when the process is created. Of course, there is a disadvantage: address translation requires extra work.
Suppose following sequence of disk track requests: 27, 129, 110, 186, 147, 41,10, 64, 120. Assume the disk head is initially positioned over track 100 and is moving in the direction of decreasing track number.a. Compare the disk scheduling algorithms with respect to the next accessed track and number of traversed tracks for FIFO, SSTF, SCAN and C-SCAN.b. What is the average seek length time for each of the algorithms? PLEASE DO FOR FIFO, SSTF, SCAN and C-SCAN. NOT FOR C-LOOK. The previous answer you gave me was for C-LOOK. Thanks.
Consider a hierarchical file system in which free disk space is kept in a free space list. a. Suppose the pointer to free space is lost. Can the system reconstruct the free space list? b. Suggest a scheme to ensure that the pointer is never lost as a result of a single memory failure.
Please give me correct solution.
Requests are not usually uniformly distributed. For example, a cylinder containing the file system FAT or inodes can be expected to be accessed more frequently than a cylinder that only contains files. Suppose you know that 50 percent of the requests are for a small, fixed number of cylinders. a. Would any of the scheduling algorithms discussed in this chapter be particularly good for this case? Explain your answer. b. Propose a disk-scheduling algorithm that gives even better performance by taking advantage of this "hot spot" on the disk. c. File systems typically find data blocks via an indirection table, such as a FAT in DOS or inodes in UNIX. Describe one or more ways to take advantage of this indirection to improve the disk performance.
Compare the main memory organization schemes of contiguous-memory allocation, pure segmentation, and pure paging with respect to the following issues: a. External fragmentation b. Internal fragmentation c. ability to share code across processes
Q3