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Assignment1 Second Semester Session 1445 AH Student Name : Student ID : Student Signature : Department Course Code Total Marks : Department of Computer Science : COCS 361 Course Name Deadline Time : Operating Systems Number of Exam Pages : 4 : Wednesday, May 05, 2024 : 11:00 – 12:00 20 Marks S.O 1 □ □ □ /10 Marks Signature: S.O 2 /10 Marks Examiner: Prof Dr Ali Ahmed Total Marks (In Figure) Total Marks (In Words) /20 Marks 1. Consider a user program of logical address of size 6 pages and page size is 4 bytes. The physical address contains 300 frames. The user program consists of 22 instructions a,b, c, . . . u, v . Each instruction takes 1 byte. Assume at that time the free frames are 7, 26, 52, 20, 55, 6, 18, 21, 70, and 90. Find the following? a) Draw the logical and physical maps and page tables? b) Allocate each page in the corresponding frame? c) Find the physical addresses for the instructions m, d,v, r? d) Calculate the fragmentation ifexist [SO1: 10.0 Marks] 2 2. Consider apaging system with the page table stored in memory a) If amemory reference takes 50 nanoseconds, how long does a paged memory reference take? b) If we add TLBs, and if 75 percent of all page-table references are found in the TLBs, what is the effective memory reference time? (Assume that finding a page-table entry in the TLBs takes 2 nanoseconds, if the entry is present.) [SO2: 4.0 Marks] 3 3. 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 How many page faults would occur for the following replacement algorithms, assuming one, three , five and seven frames? Remember that all frames are initially empty, so your first unique pages will cost one fault each. a) LRU Replacement b) FIFO Replacement c) Optimal Replacement [SO2: 6.0 Marks] 4