Your program will read a file called ‘memory.dat’ containing information about the processes in the system.Operating System

Memory Management

The Assignment

 Your program will read a file called ‘memory.dat’ containing information about the processes in the system, and how they are accessing memory. Each line of the memory.dat adheres to the following format:

PROCESS_ID       ACTION      PAGE

The PROCESS_ID field is a numeric value corresponding to a process running on the system. The ACTION field is interpreted variously:

  • ‘C’ means the process is created (‘PAGE’ field not present)
  • ‘T’ means the process terminated (‘PAGE’ field not present)
  • ‘A’ means the process allocated memory at address ‘PAGE’
  • ‘R’ means the process read ‘PAGE’
  • ‘W’ means the process wrote to ‘PAGE’
  • ‘F’ means the process freed memory at address ‘PAGE’

For example, a sample memory.dat file for two processes might contain:

 

100

C

 

100

A

1

100

W

1

100

R

1

200

C

 

100

A

2

200

A

1

200

W

1

200

R

1

100

T

 

200

T

 

 

Your program should implement a virtual memory system with 20 total physical pages, and infinite swap. For each line read from the memory.dat file, simulate what the system would do with each of the following memory/swap policies:

  • FIFO
  • LRU
  • Random

For each of the above policies, first check if there are unmodified pages available to be immediately reclaimed. If so, use those pages first. If no unmodified pages exist, fall back to the algorithm currently in use.

It may be easier to perform each of the above simulations separately (eg, read memory.dat, run the FIFO simulation, then reset, read memory.dat again, perform LRU, etc).

At the conclusion of each of the above simulations, output the following:

 

  • The page table for each process
  • The content of the 20 pages of physical memory

 

You do not need to consider the following:

  • Pages used for the OS
  • Pages used for the page tables themselves

You may choose any swap placement scheme you wish, but do keep track!

A sample output might look like the following (note this does not match the previous example):

 

PROCESS 1

Virtual

1

Physical

4

Virtual

3

Physical

17

 

PROCESS 2

Virtual            7          Physical          1

Virtual            6          Swap

SWAP

Process           2          Virtual            6

 

 

PHYSICAL

0

FREE

 

1

Process

2

2

FREE

 

3

FREE

 

4

Process

1

 

 

 

 

20

FREE

 

 

If a process accesses or frees a page it has not previously allocated, that process is immediately killed. In this case, your output should reflect this:

PROCESS 3  KILLED

Notes:

  • When a process terminates, all its pages are freed
  • If a process is not terminated when the simulation ends, print its final configuration (without freeing its pages)
  • Process IDs can repeat, but will always be ‘T’erminated before re-’C’reated
  • You do not need to consider code vs data pages
  • A process will always be ‘C’reated before any memory is accessed by that process

 

I don’t have a requirement for the precise output format, but it should be easy to understand, such as shown above.

Start by creating a new github repository for your code. You can sign up for a free github account online if you don’t have one already. Each team member should have their own account, but it does not matter which account owns the repository for this assignment. The repository can be either public or private.

Please do not re-use the assignment 1 or 2 repository (make a new one for this assignment).

Next, develop the basic framework – reading the memory.dat file, for example. After you have that working, you can split up the remaining work among your team members. It is up to each team to agree on an equitable division of work among the team members.

Teams are strongly urged to “commit early, commit often” - this means as soon as you have something working, push your changes to your team’s repository. This ensures that everyone has access to the latest code, and also serves as a backup in case your copy of the code gets messed up.

Attachments:

Instructions Files

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