《操作系统》试题

西北大学软件学院2004级《操作系统》期末试题1.Give definitions of the following terms: (10 points ,2 points each)
(1) Process:
(2) DMA:
(3)Deadlock:
(4) External fragmentation:
(5) SPOOLing:
2.Answer the following questions briefly (30 points,6 points each)
1)What are the typical elements of a process?
2)List the possible events to trigger a process switch, and what are the
steps involved in a full process switch?
3)List the general information used in real-time task scheduling.
4)For the seven-state process model, draw queuing diagram to describe
the implementation of process state transition.
5)Why should we introduce threads in the modern operating system?
And discuss the relationship between thread and process. (choose 6 questions to answer from the following 8 questions, 10 point each )
3.Give a solution to the bounded-buffer Producer/Consumer problem
using semaphores if the consuming speed is always higher than that of producing.
4.Consider a system with a total of 150 units of memory, allocated to
Apply the banker’s algorithm to determine whether it would be safe
to grand each of the following requests. If yes, indicate a sequence of terminations that could be guaranteed possible. If no, show the reduction of the resulting allocation table .
a. A fourth process arrived, with a maximum memory need of 60
and an initial need of 25 units.
b. A forth process arrived , with a maximum memory need of 60
and an initial need of 35 units.
5.In a paging and segmentation combined virtual memory management
system, assuming a page size of 1 Kbytes, describe the process of mapping the logical address to the physical address when executing the instruction LOAD 2|3500 ,and draw the address translation diagram.
6.
For each of the following scheduling algorithms, FCFS, SPN, HRRN, determine the process scheduling sequence and calculate the average turnaround time respectively
7.In a paging virtual memory management system, consider the following
page reference string :4,3,2,1,4,3,5,4,3,2,1,5 , with a working set of 4 frames, initially all empty. Compute how many page faults would occur for the page replacement policies of FIFO and LRU respectively? And show the replacement process.
8.Besides first-fit ,best-fit and next-fit, another placement algorithm for
dynamic partitioning is referred as worst-fit. In this case, the largest free block of memory is allocated. Discuss the pros and cons of this method compared to first- , next-, and best-fit.
9.Consider a disk with 200 tracks numbered from 0 to 199 , assuming
that the disk head is initially positioned over track 100 and is moving in the direction of increasing track number . The requested tracks, in the order of received, are 55, 58, 39, 18, 90, 160, 150, 38, 184. For the disk scheduling algorithms, SSTF, SCAN, and C-SCAN, give the response sequence to the above requests and calculate the average seek length respectively.
10.Consider the organization of a UNIX file as represented by the Inode .
Assume that there 12 direct block pointers, and a simply, doubly and triply indirect pointer in each Inode. Further, assume that the system block size and the disk sector size are both 8k. If the disk block pointer is 32 bits, with 8 bits to identify the physical disk, and 24 bits to identify the physical block, then
1)What is the maximum file size supported by the system?
2)What is the maximum file partition supported by the system?
3)Assume no information other than the file Inode is already in main
memory , how many disk access are required to access the byte in
position 13423956?。