Implementation of modern memory management system , Operating System

Central to implementation of a modern memory management system is the page replacement algorithm. Modern virtual memory systems break memory up into pages and map (via a page table) only the pages needed, or a maximum number of pages that is constrained by system load, into the address space of the process. The page replacement algorithm is used to decide which page/s of memory to evict when different pages of memory are needed.

Using the simulators provided you will develop an understanding of the algorithms involved and perform a comparison of the efficiency of these algorithms.

2. The Simulators

The speci?cations of the simulators are as follows:

  • Only a single process run is simulated, so all the available physical memory constitutes the resident set for this process. This represents ?xed allocation, local scope policy for the resident sets.
  • The physical memory size (in frames) is an input parameter to the program. This should be less than the number of virtual pages, so some of the process pages will not ?t into physical memory.
  • The virtual address is 16-bit long. The page is addressed by the high-order 8 bits, and the offset within the page by the low-order 8 bits, so there are 256 virtual pages, each capable of holding 256 bytes.

The following data structures are provided:

  • A linear page table, which maps the virtual page number to a physical frame number. Each page table entry contains the physical frame number, and a valid bit. Other control bits or items should be added to facilitate implementation of the chosen page replacement strategy.
  • A free list, which is a list of all frames in physical memory available for allocation to the process. Initially all available frames belong to this list.
  • A resident set, which is a list of physical frames allocated to the process. Initially  this list is empty.

Initially all available frames are free, and can be allocated to the process on demand. When the free list runs out of frames, one of the frames in the resident set must be freed for the incoming page. The choice of the victim page is governed by the replacement policy.

The execution of the process is simulated by the pager program which reads virtual addresses from the input ?le, and allocates new frames to the process as required.

3 Simulator Algorithms

Three simulators (that share a common codebase) have been provided. They implement the following algorithms:

  • FIFO
  • LRU
  • Optimal

You should research each of these algorithms and develop an understanding of how these algorithms work. You do not need to understand the code beyond the level of how to run the simulators.

4 Algorithm Comparison

Four input ?les have been provided that simulate different process workloads. You should use these as input to the simulators, varying the memory size to determine which is the most ef?cient algorithm for each input, and which is the most ef?cient overall. Plotting available memory versus page fault rate will help you in this task. A spreadsheet has also been provided to assist you in making these plots.

You should after performing these experiments be able to make a recommendation about which algorithm is best for use in a real system.

5 Deliverable and Marking Guide

You are required to write a report that includes the following information, with the marks available are indicated on the right hand side:

  • Introduction to the report
  • Description of "FIFO"
  • Description of "LRU"
  • Description of "Optimal"
  • Description of experiments performed, this should be an overview of the techniques used, the results will pin this down.
  • Presentation of results for input ?le 1, (this could just be a graph), and a ranking of the three algorithms performance.
  • Presentation of results for input ?le 2 and a ranking of the three algorithms performance.
  • Presentation of results for input ?le 3 and a ranking of the three algorithms performance.
  • Presentation of results for input ?le 4 and a ranking of the three algorithms performance.
  • Conclusions and recommendation of algorithm, this should be supported by your data.
Posted Date: 2/25/2013 5:21:13 AM | Location : United States







Related Discussions:- Implementation of modern memory management system , Assignment Help, Ask Question on Implementation of modern memory management system , Get Answer, Expert's Help, Implementation of modern memory management system Discussions

Write discussion on Implementation of modern memory management system
Your posts are moderated
Related Questions
How is memory management done using bit maps? A bit map is here in this we signify the bit value as 0 or 1. 1-hole 0-process In this we are able to represent the proce

Compare user threads and kernel threads. User threads:- User threads are supported above the kernel and are executed by a thread library at the user level. Thread creation

Q. Give the reasons why Windows XP, Solaris and Linux implement multiple locking mechanisms. Explain the circumstances under which they use mutexes, spinlocks, semaphores, adaptiv

DIFFERENT MULTITHREADING MODELS Multithreading Models the majority multithreading models fall into one of the following categories of threading implementation: 1.      M

(Add synchronization to your solutions to HW 3 to eliminate all of the race conditions.  You should not remove any of the sleep() commands that you used to produce the race conditi

Explain a working of file control block A file control block (FCB) has information about the file, containing ownership, permission, and location of the file contents. The log

Define the Communications Techniques - Application interaction protocols    Communications techniques are well defined. They give developer the programmatic mechanism to transf

ADVANTAGES AND INCONVENIENCES OF KLT Advantages: the kernel be able to simultaneously schedule many threads of the same process on many processors blocking

What are the methods for handling deadlocks ? The technique for handling the deadlocks are: We are able to use protocol to prevent or avoid the deadlock, make sure tha

Explain the ScheduleWorkToDo Function used in Netware ScheduleWorkToDo(MyThread Function, arg, workToDo) The ScheduleWorkToDo ( ) function is specific to NetWare 4.0. This c