PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....

Sean DiZazzo half.italian at gmail.com
Thu Sep 11 02:21:46 CEST 2008


On Sep 10, 3:33 pm, "Daniel Fetchinson" <fetchin... at googlemail.com>
wrote:
> > I know I'm tooooo late to ask you for help....but please help me out..I
> > am really new to unix and dont know how to finish this assignment on
> > time.....proff. said he will be using MOSS to detect whether I
> > downloaded the code..please help me..
>
> > email me : vaidehi.pa... at yahoo.co.in
>
> > Assignment 1
> > Processes, Inter-Process Communication, and Concurrency
> > Due September 13th midnight
> > Summary
> > In
> > this assignment, you will create two versions of a simple multi-process
> > game : one without and another with inter-process synchronization. You
> > will also measure the relative performance of the two versions of your
> > multi-process game.
> > Objectives
>
> >     * Learn how to create and terminate processes.
> >     * Learn use of inter-process communication using shared memory,
> > semaphores, signals, etc.
> >     * Learn the basic workings of CPU scheduling code in Linux.
>
> > Part A: Multi-Process Game of Turns
>
> > In
> > this part, you are asked to write a simple program that takes two
> > command-line arguments P and N. The main process creates P other child
> > processes, waits for all of them to complete, and then exits. All the
> > child processes form one logical ring among each other. (In rest of the
> > description, the term "process" refers to a "child process".) For
> > example, if the processes are numbered 1 to P, then
>
> >     * The next neighbor of process 1 is process 2,
> >     * The next neighbor of process i is process i+1 for all i < P , and
> >     * The next neighbor of process P is process 1, which completes a ring
> > among the processes.
>
> > Assume
> > that a shared integer variable, called turn, identifies the number of
> > the processes whose turn it is at any instant. A second process-local
> > variable in each process, called me, identifies the identity of each
> > process (i.e. each process stores its own identity in a per-process
> > local variable me). A third per-process local variable, called next,
> > identifies the next process in the ring.
>
> > The processes
> > sequentially pass the turns among each other in the logical ring. When
> > each process gets its turn, it increments another shared variable
> > called counter. The pseudo-code within each process for passing turns
> > might look something as follows. (Note: Replace turn and counter below
> > with appropriate ways of accessing data within shared memory regions).
>
> >     while(turn != me )
> >         /* do nothing - just busy loop*/ ;
>
> >     /* got my turn - increment counter */
> >     counter = counter + 1;
>
> >     /* give the turn to next process */
> >     turn = next;
>
> > The program terminates when the each process has received N turns.
>
> > In the above description, several programming details have been omitted for
> > you to figure out. This includes
>
> >     * Creating P child processes from main process.
> >     * Constructing the logical ring among child processes.
> >           o Initializing each child process's identity in the me variable.
> >           o Initializing each child process' next neighbor in the next
> > variable.
> >     * Initializing the shared memory region and the shared data values.
> >     * Have the main process wait for child processes to complete N turns
> > before exiting.
>
> > Part B: More Efficient Game of Turns
>
> > You
> > might notice that the program you wrote in Part A is inefficient
> > because each process busy loops till the CPU scheduler kicks it out
> > (after its time-slice is over) and allows another process to execute
> > and make progress. (Does the program in Part A have a race condition?
> > Why or why not?)
>
> > What we ideally want is that each process
> > should be given control of the CPU only when it is that process' turn.
> > Modify the program you wrote in Part A (using appropriate
> > synchronization mechanisms) such that each process gets to run (i.e.,
> > gets control of the CPU) only when it is that process's turn, and at no
> > other time.
>
> > Again, you would need to work out the programming details of how and where
> > to use inter-process synchronization.
> > Part C: Profiling the Game of Turns
>
> > In
> > this part, you are asked to write user-level profiling code in order to
> > measure the performance of the two versions of programs you wrote in
> > Part A and Part B. Use a combination of gettimeofday() system call and
> > inter-process synchronization to measure (1) the average hand-over time
> > between two consecutive processes in the ring and (b) the total
> > execution time to complete N turns. Plot the measured values as graphs
> > when varying number of processes P and number of turns N. Explain the
> > results you obtain.
> > Submission Guidelines
>
> > Thanking you,
>
> > Ms. Vaidehi Pawar
>
> How much do you pay?
>
> Cheers,
> Daniel
> --
> Psss, psss, put it down! -http://www.cafepress.com/putitdown

Maybe.  If I cant sleep tonite.



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