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Learning Goal: I’m working on a operating systems question and need support to help me learn.

You must submit two separate copies (one Word file and one PDF file) using the Assignment Template on Blackboard via the allocated folder. These files must not be in compressed format.

It is your responsibility to check and make sure that you have uploaded both the correct files.

Zero mark will be given if you try to bypass the SafeAssign (e.g. misspell words, remove spaces between words, hide characters, use different character sets, convert text into image or languages other than English or any kind of manipulation).

Email submission will not be accepted.

You are advised to make your work clear and well-presented. This includes filling your information on the cover page.

You must use this template, failing which will result in zero mark.

You MUST show all your work, and text must not be converted into an image, unless specified otherwise by the question.

Late submission will result in ZERO mark.

The work should be your own, copying from students or other resources will result in ZERO mark.

Use Times New Roman font for all your answers.

3 Marks

Learning Outcome(s):

Describe the OS mechanism for process management, threads, memory, storage management, I/O, file and concurrency management. Evaluate the effectiveness of different techniques in processes, devices and memory management.

Question One

A wait-for graph can be constructed from a Resource Allocation Graph by eliminating the resources and collapsing the associated edges. Using Resource Allocation Graph, it can be easily detected whether system is in a deadlock state or not. Draw the wait-for graph using the following Resource Allocation Graph and state weather it is in a deadlock state and why?

1 Marks

Learning Outcome(s):

Explain the rational for storage management, memory management and virtual memory concepts.

Question Two

The hit ratio is the percentage of times that a page number is found in the Translation look-aside buffer (TLB). An 80% hit ratio means that we find the desired page number in the TLB 80% of the time.

Suppose we have a hit ratio of 70% and 40 ns is needed for TLB, where main memory access time is 80 ns. Calculate the EAT (effective access time) and what is the percentage of slowdown predicted?

2 Marks

Learning Outcome(s):

Explain the rational for storage management, memory management and virtual memory concepts.

Question Three

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.

Suppose the frame number is four (4), how many page faults would occur for the following replacement algorithms? demonstrate the page replacement processes with the following algorithms.

Remember that all frames are initially empty, so your first unique pages will cost one fault each.

  • FIFO replacement
  • LRU replacement
  • 2 Marks

    Learning Outcome(s):

    Recognize the services and system calls of modern operating systems

    Question Four

    Suppose that a disk drive has 5,000 cylinders, numbered 0 to 4,999. The drive is currently serving a request at cylinder 2,100, 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; 3,681

    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?


    B-C-SCAN (the head by default goes to the higher cylinder first.)