problem17

On a 32-bit processor, a baggy bounds scheme is expected to set all of the bounds table entries to 31 at initialization time. Assume that a buggy implementation with a slot size of 32 bytes performs bounds table initialization inappropriately, resulting in random entries being incorrectly set to 1. Assume that a networked server processes network messages using an uninstrumented library. Assume that this library does not include some buffer overflow bugs (i.e., it never calls unsafe functions such as gets()). However, the server suffers from the above-mentioned bounds table initialization issue, and an attacker may submit messages to the server that force the library to dynamically assign and write memory in an attacker-controlled amount using uninstrumented code that looks like this: / N is the size of the buffer that the intruder gets to choose.for (int I = 0; I N/4; i++, p += 4) char *p = malloc(N); *p = 'a'; *(p+1) = 'b'; *(p+2) = 'c'; *(p+3) = 'd'; Assume the server is using a…

Using the following page replacement algorithms, determine the number of faults in the following reference string given a physical memory size of 4 frames: 5  6  5  4  4  4  8  2  9  9  0  4  5  3  9  6  8  1  9  1  6  1  0  0  5   Replacement algorithm 3 frames FIFO   OPT   LRU   LFU   MFU

a) Consider the following page reference string: 1, 2, 5, 3, 4, 6, 7, 7, 1, 0, 5, 4, 6 a) A paging scheme with THREE (3) frames initially empty are considered. Trace the allocationof pages to frames and determine the number of page faults occur using the First-in-First-out(FIFO) page replacement algorithm.  b) Assume a system is able to support up to 2,000 users. Suggest a UNIX protection schemewhich allows access to a single file named “MPX.pdf” for 1,990 users. How would you treatthe remaining 10 users who shall not be given access to the file?

Consider the following code snippet in C: char *base_url = malloc(11 * sizeof(char)); printf("Enter an 11 character URL: "); scanf("%s", base_url); char src[11]; char dst[11];   // copies base_url to src strncpy(src, base_url, 11);   // copies src to dest strcpy(dst, src); printf("src: %s dst: %s\n", src, dst);   Identify at least one potential buffer overflow vulnerability and explain why/how it can be exploited (i.e., not just that it’s a buffer overflow, but where the problem will manifest itself).

Using the following page replacement algorithms, determine the number of faults in the following reference string given a physical memory size of 4 frames: 5  6  5  4  4  4  8  2  9  9  0  4  5  3  9  6  8  1  9  1  6  1  0  0  5 OPT.     3 frames

Consider the following page reference string: 7, 2, 3, 1, 2, 5, 3, 4, 6, 7, 7, 1, 0, 5, 4, 6, 2, 3, 0, 1. Assuming pure demand paging with three frames (3 pages can be in memory at a time).   a)Using FIFO replacement algorithm, show the content of the memory (which pages are in memory) for each page reference. b) How many page faults resulted from this algorithm? c) Repeat a) and b)above with LRU algorithm.

5.03-1. Dijkstra's Algorithm (3, part 1).  Consider the network shown below, and Dijkstra’s link-state algorithm. Here, we are interested in computing the least cost path from node E (note: the start node here is E) to all other nodes using Dijkstra's algorithm. Using the algorithm statement used in the textbook and its visual representation, complete the "Step 0" row in the table below showing the link state algorithm’s execution by matching the table entries (i), (ii), (iii), and (iv) with their values.

Consider the bitmap representation of the free-space map, where for eachblock in the file, two bits are maintained in the bitmap. If the block is between0 and 30 percent full the bits are 00, between 30 and 60 percent the bits are01, between 60 and 90 percent the bits are 10, and above 90 percent the bitsare 11. Such bitmaps can be kept in memory even for quite large files. Outline the benefit of the bitmap technique over free lists in searching for free space and in updating free space information.

Consider the following page reference string:2   4   2   8   5   4   3   7   5   2   8   4   6   8   3Assume that FOUR (4) frames are initially empty in the memory. Perform the page faults trace analysis to determine the number of page faults that will occur for each of the following page replacement algorithms.  (i) First-In-First-Out (FIFO), Least-Recently-Used (LRU) and Optimal Page Replacement

question 3 : With the same physical memory and the same initial page assignments as in question 1, how many page faults will occur If Optimal page replacement is used ? Assume the reference string (RS) is the same 0172327103? Time t 0 1 2 3 4 5 6 7 8 9 10 RS   0 1 7 2 3 2 7 1 0 3 Frame 0 0                     Frame 1 1                     Frame 2 2                     Frame 3 3                       please find the below question 1 for reference as stated in question 3 above and please answer question 3 accordingly: question 1 : The physical memory consists of 4 frames: 0 through 3. Initially, the frames contain the pages 0 through 3 (as shown at time 0). If FIFO page replacement is used, how many page faults will occur with the reference string (RS) 0172327103?

Suppose that a disk drive has 5,000 cylinders, numbered 0 to 4,999. The drive is currently serving a request at cylinder 2,150, and the previous request was at cylinder 1,805. The queue of pending requests, in FIFO order, is:2,069 1,2122,2962,8005441,6183561,5234,9653681a. FCFSb. SSTFc. SCANd. LOOKe. C-SCANf. C-LOOK

1(c) What is the best-case time complexity for inserting n items into a hash table of size m? When willthe performance of an open addressing hash table degrade no matter what collision resolutionscheme is used?

Consider the following page address stream: 2 1 4 3 5 3 2 4 5 2 1 2 4 3 1 Which of the following causes the most page faults to occur on a machine with 3 frames? Scheme that causes the most faults: a) First in First out b) LRU and FIFO are the same number of faults c) FIFO and Opitimal are the same number of faults d) All have the same number of faults e) Least Recently Used f) No faults occurs g) LRU and Optimal are the same number of faults h) Optimal NUMBER OF FAULTS CAUSED: a)

Implement c/c++ to evaluate round robin algorithm with i/o burst.I want my code to able to read csv. The link is to my csv file https://jpst.it/2IURz. The code must also have input for quantum time. The code must contain this following:(i) Turnaround time of the jobs;(ii) Waiting time of the jobs; and(iii) Number of interrupts incurred

Q 1  Computer Science Theory and Fundamentals of Operating Systems: Reference String: 7,6,8,2,6,3,6,4,2,3,6,3,2,8,2,6,8,7,6,8 How many page faults will occur if the program has three page-frames available to it and use Optimal replacement?

Consider the following page reference string for a 12-page executable. 0,1,1,3,4,10,5,2,2,10,6,6,10,11,7,8,7,9,9,6,5,11,9,11How many page faults would occur for the following replacement algorithms, assuming one, two, and four frames?Remember that all frames are initially empty, so your first unique pages will cost one fault each.a. LRU replacementb. FIFO replacementc. Optimal replacement

1. Which algorithm chooses the page that has not been used for the longest period of time whenever the page required to be replaced? a.)Optimal b.)LRU c.)Second chance d.)Clock   2. In memory management with valid–invalid bit, the valid bit indicates that the page is: a.) illegal access. b.)not in memory c.)in memory. d.)not legal.

“Dirty bit is used to reduce the overhead of page transfer”. Statewhether the given statement is true or false. Justify your answer withsuitable example.

5.14. SDN implementation of Dijkstra’s algorithm. Consider the implementation of Dijkstra’s algorithm in an SDN framework. Which of the following statements are true? (Hint: more than one statement is true.) Group of answer choices a. When executing, Dijkstra’s algorithm will need to send messages to all of the routers to gather their link costs. b. When executing, Dijkstra’s algorithm will use the link-state database that is maintained within the SDN controller. c. When executing, Dijkstra’s algorithm will execute within the operating system of the SDN controller d. When executing, Dijkstra’s algorithm will run as a network control application “on top” on the SDN controller. e. If a router’s forwarding table should be changed as a result of running Dijkstra’s algorithm, the new flow table for that router will be updated by the SDN controller via the southbound API using the Openflow protocol. f. If a router’s forwarding table should be changed as a result of running Dijkstra’s…

Suppose that a disk drive has 5,000 cylinders, numbered 0 to 4,999. The drive is currently serving a request at cylinder 2,150, and the previous request was at cylinder 1,805. The queue of pending requests, in FIFO order, is: 2,069, 1,212, 2,296, 2,800, 544, 1,618, 356, 1,523, 4,965, 3681 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for each of the following disk- scheduling algorithms? e. C-SCAN f. C-LOOK

5.01-3. Dijkstra's Algorithm (1, part 3).  Consider the network shown below, and Dijkstra’s link-state algorithm to find the least cost path from source node U to all other destinations.  Using the algorithm statement and its visual representation used in the textbook,complete the third row in the table below showing the link state algorithm’s execution by matching the table entries (a), (b), (c), (d) and (e) with their values

Consider the following page reference string: 1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 What are the last pages in main memory in their order, and how many page faults would occur for the following page replacement algorithms? Assuming 4 frames. A) FIFO B) Optimal C) LRU

Use C, C++, python or matlab to develop a program whose main routine accepts two parameters n and k, i.e. when you invoke your program from the shell, you pass it two parameters, n and k, where n >=16 and k >=8and is in powers of 2 (e.g. 8, 16, 32, etc.). Your main routine shall generate a random page trace of length n, where the page numbers have values ranging from 0 to ? − 1. Develop a subroutine within your program that implements the FIFO page replacement algorithm (as a separate function within your program). The function shall accept a page trace and a parameter f for the number of frames allocated. Your main routine shall then apply the random page trace to the subroutine implementing the page replacement algorithm, multiple times (using only one trace, randomly generated), passing a parameter f (number of page frames used) that ranges from 4 to k. Your main routine shall then record the number of page faults for each run (i.e. for each f).Run your program using a page…

A computer uses virtual memory, and a new solid-state drive (SSD) as space for paging. Refer to the last ppt file. In the case presented there, the hard disk drive (HDD) required 25 ms to read in a page, and a rate of 1 page fault per 1000 references introduced a 250 slowdown. If the SSD offers a time of only 80 µs, what is the slowdown in performance caused by 1 pf per 1000 references (you are not concerned with dirty vs. clean pages). What is the maximum rate of page faults you can accept if you want no more than a 5% slowdown in execution using virtual memory? Know your metric prefixes and symbols for time: s for seconds, ms for milliseconds, µs for microseconds, ns for nanoseconds.

Write OPT Page Replacement Algorithm In C The user of your program should be able to: Specify a data file of page requests using a command line argument. Specify the size of the resident set (number of frames) using a command line argument. Specify the number of pages in the program using a command line argument. Simulate the running of each page replacement algorithm and determine the number of page faults.