Professor Shai Simonson - CSC 304 - Computer Architecture



Assignment 7

Memory Hierarchies:  Cache and Virtual Memory

 

Due: By the final exam

In the book.  (15 points)


Chapter 5:  5.2 (only parts 1-3), 5.3, 5.5, 5.7, 5.11 (only parts 1-4), 5.13.



1.    
This problem puts everything together:  Virtual memory, set associative TLB, and direct mapped multi-byte block cache.  It is an important example to understand and practice. 

        Refer to the Page table, TLB, and Cache table below to answer these questions. 
        Note the
standard practice, as used in this example below, is that valid = 1 means that the data is in RAM, and valid = 0 means a page fault.


What would happen if a CPU tries to access the following virtual addresses? 

 

a)      0x0364 

 

b)     0x033D

 

c)     0x036B


For each case:  Is there a TLB hit or miss? Is there a cache hit or miss?  What is the result of the memory access or is there a page fault?

 



Addressing

  14-bit virtual address

  12-bit physical address

Page size = 64 bytes




 

Page Table (first 16 entries only)

VPN

PPN

Valid

VPN

PPN

Valid

00

28

1

08

13

1

01

-

0

09

17

1

02

33

1

0A

09

1

03

02

1

0B

-

0

04

-

0

0C

-

0

05

16

1

0D

2D

1

06

-

0

0E

11

1

07

-

0

0F

0D

1

 

TLB

16 entries

4-way associative

 

 

Set

Tag

PPN

Valid

Tag

PPN

Valid

Tag

PPN

Valid

Tag

PPN

Valid

0

03

-

0

09

0D

1

00

-

0

07

02

1

1

03

2D

1

02

-

0

04

-

0

0A

-

0

2

02

-

0

08

-

0

06

-

0

03

-

0

3

07

-

0

03

0D

1

0A

34

1

02

-

0

 

Cache

16 blocks

4-byte block size

Direct mapped




Idx

Tag

Valid

B0

B1

B2

B3

Idx

Tag

Valid

B0

B1

B2

B3

0

19

1

99

11

23

11

8

24

1

3A

00

51

89

1

15

0

-

-

-

-

9

2D

0

-

-

-

-

2

1B

1

00

02

04

08

A

2D

1

93

15

DA

3B

3

36

0

-

-

-

-

B

0B

0

-

-

-

-

4

32

1

43

6D

8F

09

C

12

0

-

-

-

-

5

0D

1

36

72

F0

1D

D

16

1

04

96

34

15

6

31

0

-

-

-

-

E

13

1

83

77

1B

D3

7

16

1

11

C2

DF

03

F

14

0

-

-

-

-

 

 


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shai@stonehill.edu

http://www.stonehill.edu/compsci/shai.htm