CSE 435- Final Exam Prep

Next fit assume the most recently added block is at

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Unformatted text preview: 20 10:160 (3) Next-fit, Assume the most recently added block is at the beginning of memory. 40:80 20:230 10:290 W16 P1 (a) What are the distinctions among logical, relitave, and physical addresses? Logical - reference to a memory location independent of the current assignment of data to memory. Translation must be made to the physical address. Relative - Address expressed as a location relative to some known point. Physical The absolute address or actual location in main memory. (b) What is the difference between a page and a frame? The chunks of a process are called pages and chunks of memory are called frames (c) What is the difference between a page and a segment? A page is a fixed size piece of a program while segments of a program can be of varying length. Problem 2 A 1Mb block of memory is allocated using the buddy sysem. a. Show the results of the following sequence in a figure: Request A for 70Kbytes Request B for 35Kbytes Request C for 80Kbytes Return A Request D for 60Kbytes Return B Return D Return C 1Mb 128k 256k 512k EMI MEN 6.; 64k 256k 512k El 1288 in 6 ti-lk k Km 6 I28k 512k 128k 512k 128k 512k 128k 512k 256k 128k 512k 1Mb b. Show the binary tree representation following Return B. Problem 9 Consider a simple paging system with the following prarmetors: 2 3 2 bytes of physical memory; page size of 2 1 0 bytes; 2 1 6 pages of logical address space. a. How many bits are in a logical address? The logical address has 10 + 16 = 26bits b. How many bytes in a frame? A frame has 2 1 0 = 1024bytes c. how many bits in the physical address specify the frame? The number of bits in a physical address used to specify the frame number is 32 — 10 = 22 bits d. how any entries in the page table? The page table contains 216 = 65536 entries e. how many bits in each page table entry? Assume each page table entry includes a valid/invalid bit. The number of bits used in each page table entry are, 22 + I = 23 bits Problem 4 Consider the following segment table: Length Segment Base 19 60 140 2300 90 100 1327 580 4 1952 196 In what physical add asses do the following virtual addresses translate? (0, 630) (1, (2, (3, (4, (a) (b) (c) (d) (e) 110) 50) 400) 112) 219 + 430 = 649 2300 t 10 = 2310 illegal reference; traps to operating system 1327 + 400 = 1727 illegal reference; traps to operating system W17 P1 (a) explain thrashing thrashing is a state in which the system spends most of it's tim swapping pieces rather than executing user instructions. (b) why is the principle of locality crucial to the use of virtual memory? because program and data refrences within a process tend to cluster. (c) What is the purpose of a translation lookaside buffer (TLB)? W17 P2 (a) What elements are typically found in a page table entry? Brief define each element. frame number of corresponding page in main memory present bit - bit to indicate if is in main mem or not modify bit - bit to indicate whether page was modified after swap (b) Compare a traditional page table with an inverte...
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This note was uploaded on 09/26/2013 for the course CSE 435 taught by Professor Cheng during the Fall '07 term at Michigan State University.

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