Find the total head movements for a request queue given below, using FCFS scheduling for a disk of 100 cylinders (0-99). It is assumed that read write head is initially present at cylinder number 50. Request queue for disk cylinders: 75, 25, 30, 68, 40, 89, 10

please no chatgpt answer . Consider a demand-paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one memory reference, if the page-table entry is in the associative memory. Assume that 80 percent of the accesses are in the associative memory and that, of those remaining, 10 percent (or 2 percent of the total) cause page faults. What is the effective memory access time? 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. Assuming demand paging with four frames, Show which pages are resident under the LRU, FIFO, and Optimal replacement algorithms by filling out the following tables. How many page faults would occur…

What is the effect on the cost of merging runs if the number of buffer blocks per run is increased while overall memory available for buffering runs remains fixed?

Consider a disk subjected to I/O requests arriving (following Poisson distribution) at an average rate of  requests/second. Assume that on average, there were 5 requests waiting for service in the queue and that each request waits in the queue for about 10 milliseconds, on average. What is the effective arrival rate  for this disk?

To what extent does disk write caching benefit from the following?

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.

Consider a system with three I/O devices: a printer, a disk, and a communications line, with increasing priorities of 2, 4, and 5, respectively.. A user program begins at t = 0. At t = 5, a printer interrupt occurs;  at t = 15, a communications interrupt occurs. While this routine is executing, a disk interrupt occurs (t = 20). Printer Interrupt service takes 10 time slots. Communication Interrupt Service takes 10 time slots. Disk Interrupt Service takes 8 time slots.   When will the control return to the user program? Show the changes in the following diagram

Consider a demand-paging system with a paging disk that has an average access/transfer time of 50 ms. Addresses are translated through a page table in main memory, with an access time of 500 ns per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added a TLB that reduces access time to one memory reference if the page-table entry is in the TLB. Assume that 80% of the accesses are in the TLB and that, of those remaining, 15% (or 3% of the total) cause page faults. We assume that the TLB access time is 20 ns. What is the effective access time?