Question

I’m writing a program in C that uses threads to add up numbers from a partitioned array that uses some obscure command line arguments to determine how many partitions should be used.

This is a copy of the part I’m struggling with from my brief:

    Divide the array into 2**n partitions (n is another command-line argument)   and create 
 one thread to do simple sum of all values stored in one partition   of the array. Each 
thread can calculate which locations of the array it should   search given the thread index
 (0,1, … 2**n-1). For example, if n=1 and the   array is size 512, then thread 0 should sum
 array locations [0,255] and   thread 1 should search array locations [256-511].  Each 
thread should store   the partial sum it produces in a global array.  Note that since the 
threads do   not share any data, they do not need to be synchronized, however you do   need
 to wait until the last thread completes processing before continuing on   to the next 
stage.

I’ve absolutely no idea how to partition the array and why threads are even necessary for this task but seeing as it’s part of my requirements I will have to use them. If someone could help explain a little clearer and the manor in which I’d go about the partitioning and the reason for threads, I’d be most grateful. I’ve already created the array and filled it with random numbers.

Answer 1

Your class might be parallel processing, and this assignment lets you do parallel addition on a given array with 2^n threads.