Week 09 Laboratory Exercises

Write a C program, diary.c, which appends 1 line to $HOME/.diary.

The line should be its command-line arguments separated by a space followed by a '\n'.

diary.c should print nothing on stdout. It should only append to $HOME/.diary.

dcc diary.c -o diary
./diary Lisa
cat $HOME/.diary
Lisa
./diary in this house
./diary we obey the laws of thermodynamics
cat $HOME/.diary
Lisa
in this house
we obey the laws of thermodynamics

When you think your program is working, you can use autotest to run some simple automated tests:

1521 autotest diary

When you are finished working on this exercise, you and your lab partner must both submit your work by running give:

give cs1521 lab09_diary diary.c

Note, even though this is a pair exercise, you both must run give from your own account before Wednesday 01 January 00:00 to obtain the marks for this lab exercise.

Your task is to simulate least-recently-used (LRU) replacement of virtual memory pages.

Write a C program, lru.c, which takes two arguments, both integers.

This will be respectively the size in pages of simulated physical memory and and the size in pages of simulated virtual memory.

lru.c should then read integers from stdin until EOF.

Each integer will be the number of a virtual page being accessed.

lru.c should print one line of output for indicate what action occurs with a phyical memory of the given size and LRU replacement.

dcc lru.c -o lru
./lru 4 6
Simulating 4 pages of physical memory, 6 pages of virtual memory
5
Time 0: virtual page 5 loaded to physical page 0
3
Time 1: virtual page 3 loaded to physical page 1
5
Time 2: virtual page 5 -> physical page 0
3
Time 3: virtual page 3 -> physical page 1
0
Time 4: virtual page 0 loaded to physical page 2
1
Time 5: virtual page 1 loaded to physical page 3
2
Time 6: virtual page 2  - virtual page 5 evicted - loaded to physical page 0
2
Time 7: virtual page 2 -> physical page 0
3
Time 8: virtual page 3 -> physical page 1
5
Time 9: virtual page 5  - virtual page 0 evicted - loaded to physical page 2

In the files for this week's lab you'be been give code which implements a suitable data structure to store information about accesses,

For each access this function is called:

void access_page(int virtual_page, int access_time, int n_physical_pages, struct ipt_entry *ipt) {

    // PUT YOUR CODE HERE TO HANDLE THE 3 cases
    //
    // 1) The virtual page is already in a physical page
    //
    // 2) The virtual page is not in a physical page,
    //    and there is free physical page
    //
    // 3) The virtual page is not in a physical page,
    //    and there is no free physical page
    //
    // don't forgot to update the last_access_time of the virtual_page

    printf("Time %d: virtual page %d accessed\n", access_time, virtual_page);
}

When you think your program is working, you can use autotest to run some simple automated tests:

1521 autotest lru

When you are finished working on this exercise, you and your lab partner must both submit your work by running give:

give cs1521 lab09_lru lru.c

Note, even though this is a pair exercise, you both must run give from your own account before Wednesday 01 January 00:00 to obtain the marks for this lab exercise.