Operating System Homework 1
This homework is to analyze and compare the performance of a computing task using multiple processes and threads.
For the computing task, prepare a large array of integers/strings/structures with contents randomly generated with repetitions. Do not sort this array. The task is to find out the number of times an inquiry element occurs in the array. Write a C program (without any threads or child process) to perform the task and measure the .execution time (using gettimeofday()). A typical output of the program may look like “Integer 13 occurs 5 times in the array.” Keep the same input and inquiry for all program tests to ensure the correctness of any program modification.
For multi-process version, the parent processes divides the array into multiple segments, one for each child process. Each child process returns (using exit()) the number of times the inquiry element occurs in that segment. The parent process takes the sum of all results reported by child processes. Refer to the following page for getting the exit status of child process.
https://support.sas.com/documentation/onlinedoc/ccompiler/doc700/html/lr2/zid9832.htm
For multi-threaded version, the main thread divides the array into multiple segments, one for each working thread. That are two ways for the main thread to take the sum of all results reported by working threads.
1) Each working thread uses pthread_exit()to return the number of times the inquiry element occurs in that segment and the main thread uses pthread_join()to get the result.
2) Define a global counter to keep the final result. Each working thread adds to the global counter the number of times the inquiry element occurs in that segment.
