splab5 - pthreads basics

Aim

• To get familiar with Pthread API

TASK A: MATHREADS

Write a program mathreads.c and compile it as mathreads. The program should accept two arguments, create four threads. Each of the threads should perfom an arithmetic operation over the arguments (like addition, subtraction, multiplication or division) as shown below. Main thread should wait for its child threads and print the result. Child threads don't print anything, they just calculate the results.

$ gcc mathreads.c -o mathreads -lpthread
$ ./mathreads 3 5
add: 3+5=8
mul: 3*5=15
sub: 3-5=-2
div: 3/5=0

TASK B: SINGLE THREADED MATRIX MULTIPLICATION

Write a program single_mult.c that will take size n of a matrix as command line argument, will create 2 matrices, A and B, of size n by n with random values. Then it will multilply A and B, store the result in C.

$ gcc single_mult.c -o single_mult
$ ./single_mult 2
A:
1 2
3 4

B:
2 1
0 1

C:
2 3
6 7

TASK C: MULTITHREADED MATRIX MULTIPLICATION

Write program that does the same task as in the previous task but each element C[i][j] should be calculated by a separate thread.

$ gcc multi_mult.c -o multi_mult
$ ./multi_mult 2
A:
1 2
3 4

B:
2 1
0 1

C:
2 3
6 7

TASK D: MEASUREMENT

1. measure running time of TASK A, and running time of similar task DOMATH of splab2. Compare them.
2. measure running time of TASK B, and running time of TASK C. Compare them.
3. measure the time of creating 100 threads (using pthread_create) vs 100 processes (using fork). Main/parent thread/process should pthread_join/wait all child threads/processes. Processes/threads don't do any jobs, just exit/pthread_exit successfully.