1.Consider a virtual memory system that can address a total of 2^50 bytes. You h
ID: 3708909 • Letter: 1
Question
1.Consider a virtual memory system that can address a total of 2^50 bytes. You have unlimited hard drive space, but are limited to only 2 GB of semiconductor (physical) memory. Assume that virtual physical pages are each 4 KB in size.
a. How many bits is the physical address?
b. What is the maximum number of virtual pages in the system?
c. How many physical pages are in the system?
d. How many bits are the virtual and physical page numbers?
e. How many page table entries will the page contain?
f. Assume that, in addition to the physical page number, each page table entry also contains some status information in the form of a valid bit (V) and a dirty bit (D). How many bytes long is each page table entry? (Round up to an integer number of bytes.)
g. Sketch the layout of the page table. What is the total size of the page table in bytes?
h. You decide to speed up the virtual memory system of problem 1, by using a translation lookaside buffer (TLB) with 128 entries. How big (in bits) is the TLB? Give numbers for data (physical page number), tag (virtual page number), and valid bits of each entry.
i. Sketch the TLB, ad label all fields and dimensions.
j. What size SRAM would you need to build the TLB described in part b? Give your answers in terms of depth x width.
Explanation / Answer
a) since 2GB = 2^31 bytes ,the physical address is 31 bits.
b) given virtual memory is 2^ 50 bytes and virtual physical size as 4 KB = 2^12 bytes so the maximum number of virtual pages is 2^ (50-12) = 2^38 page size
c) physical pages in syatem =physical address/ physical size = 2^31/2^ 12 = 2^19physical pages
d) The virtual page number is 38 bits as in bit b and physical page number is 19 bits as in bit c
e) a page table contains 1 page for entry so a total of 2^38 page entries
Post the remaining questions as another query as of chegg guidelines
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