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Josue Mosh
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Quicksort using threads
1 parent 04f6619 commit 212ebbd

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4 files changed

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4 files changed

+269
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‎Practices/P1/multi-thread/multi-thrd.c

+6-6
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@@ -1,15 +1,15 @@
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/**
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* A pthread program illustrating how to create a simple
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* thread and some of the pthread API.
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* A pthread program illustrating how to create multiple
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* threads and some of the pthread API.
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* This program implements the summation function where
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* the summation operation is run in multiple threads.
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*
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* Most Unix/Linux/OS X users
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* gcc multi-thrd.c thrd-posix.c -lpthread -lrt
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*
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* @author Gagne, Galvin, Silberschatz
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* Operating System Concepts - Ninth Edition
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* Copyright John Wiley & Sons - 2013
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* @author Josue Mosiah Contreras Rocha
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* @file multi-thrd.c
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* @date 09/02/2020
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*/
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// ------------------------------------------
@@ -104,7 +104,7 @@ int main(int argc, char *argv[]) {
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/**
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* The thread will begin control in this function.
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*
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* @param params Thread's attributes.
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* @param params Range for each thread.
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*/
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void *runner(void *params) {
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// Initial set up for the thread

‎Practices/P1/sort/quicksort.c

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/**
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* A pthread program illustrating how to create multiple
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* threads and some of the pthread API.
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* This program implements the quicksort algorithm where
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* the operation is run by multiples threads.
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*
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* Most Unix/Linux/OS X users
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* gcc quicksort.c thrd-posix.c -lpthread -lrt
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*
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* @author Josue Mosiah Contreras Rocha
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* @file quicksort.c
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* @date 09/02/2020
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*/
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// ------------------------------------------
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// System and aplication specific headers
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// ------------------------------------------
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#include <pthread.h>
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#include <semaphore.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include "thrd-posix.h"
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// ------------------------------------------
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// Shared variables
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// ------------------------------------------
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static int *arr;
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static sem_t mutex;
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// Prototypes
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void *runner( void *params );
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void swap( int *a, int *b );
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int partition( int lower, int upper );
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void quickSort( int lower, int upper );
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/**
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* Main thread.
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*/
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int main(int argc, char *argv[]) {
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// Validate console arguments
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if ( argc != 2 ) {
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fprintf(stderr, "usage: a.out <integer value>\n");
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exit(EXIT_FAILURE);
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}
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if ( atoi(argv[1]) < 0 ) {
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fprintf(stderr, "Argument %d must be non-negative\n", atoi(argv[1]));
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exit(EXIT_FAILURE);
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}
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// Fill array with random numbers
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int arraySize = atoi(argv[1]);
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arr = malloc(sizeof(int) * arraySize);
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srand(0); /* Seed */
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for( int i = 0; i < arraySize; ++i )
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arr[i] = rand() % 50;
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printf("Unsorted array:\n");
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for ( int i = 0; i < arraySize; ++i )
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printf("%d%s", arr[i], i == (arraySize - 1) ? "\n\n" : " ");
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// Initialize threads
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const unsigned int THREADS = 1;
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// const unsigned int THREADS = getThreads(); // This approach is faulty
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pthread_t *tid = (pthread_t *) malloc(sizeof(pthread_t) * THREADS);
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pthread_attr_t attr;
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// Sort's range for each thread
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int rangeSize = arraySize / THREADS;
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int range[THREADS * 2];
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int first = 0, second = rangeSize - 1;
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for( int i = 0; i < THREADS; ++i ) {
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// Fill
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range[i * 2] = first;
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range[(i * 2) + 1] = i == (THREADS - 1) ? arraySize - 1 : second;
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// Update
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first += rangeSize;
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second += rangeSize;
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}
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// Create threads
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sem_init(&mutex, 0, 1); /* Create semaphore */
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pthread_attr_init(&attr); /* Default attributes */
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for( int i = 0; i < THREADS; ++i ) {
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pthread_create(&tid[i], &attr, runner, &range[i * 2]);
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pthread_join(tid[i], NULL); /* Wait for threads */
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}
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// Results
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sem_destroy(&mutex); /* Destroy semaphore */
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printf("Sorted array:\n");
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for ( int i = 0; i < arraySize; ++i )
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printf("%d%c", arr[i], i == (arraySize - 1) ? '\n' : ' ');
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}
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/**
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* The thread will begin control in this function.
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*
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* @param params Range for each thread.
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*/
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void *runner(void *params) {
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// Initial set up for the thread
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int *param = (int *)params;
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int lower = param[0], upper = param[1];
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// Operations
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quickSort(lower, upper);
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pthread_exit(0);
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}
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/**
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* Swap two elements at memory level.
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*
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* @param a First element.
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* @param b Second element.
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*/
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void swap( int *a, int *b ) {
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int t = *a;
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*a = *b;
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*b = t;
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}
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/**
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* Sorts a file-scope array with the quicksort algorithm.
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*
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* @param lower Starting index.
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* @param upper Ending index.
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* @return Position of the first element in the next partition.
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*/
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int partition( int lower, int upper ) {
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// Initialize
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int pivot = arr[upper];
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int i = lower - 1; // Index of smaller element
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// Operations
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for ( int j = lower; j <= upper - 1; ++j ) {
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if ( arr[j] < pivot ) {
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// Increment index of smaller element
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i++;
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// Critical section
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sem_wait(&mutex);
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swap(&arr[i], &arr[j]);
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sem_post(&mutex);
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}
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}
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// Critical section
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sem_wait(&mutex);
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swap(&arr[i + 1], &arr[upper]);
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sem_post(&mutex);
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return (i + 1);
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}
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/**
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* Implements the QuickSort algorithm.
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*
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* @param lower Starting index.
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* @param upper Ending index.
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*/
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void quickSort( int lower, int upper ) {
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if ( lower < upper ) {
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// Partitioning index
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int pi = partition(lower, upper);
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// Sort elements before and after partition
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quickSort(lower, pi - 1);
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quickSort(pi + 1, upper);
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}
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}

‎Practices/P1/sort/thrd-posix.c

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// See compressor.h for more info
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// Author: Josue Mosiah Contreras Rocha
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// File: thrd-posix.c
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// Date: 05/02/20
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// ------------------------------------------
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// System and aplication specific headers
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// ------------------------------------------
9+
#include <stdlib.h>
10+
#include "thrd-posix.h"
11+
12+
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// -----------------------------
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// Public elements
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// -----------------------------
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// Public functions
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/**
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* Get the number of cores the system has.
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*
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* @return Number of cores.
23+
*/
24+
unsigned int getCores( void ) {
25+
unsigned int eax = 11, ebx = 0, ecx = 1, edx = 0;
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asm volatile("cpuid"
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: "=a"(eax),
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"=b"(ebx),
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"=c"(ecx),
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"=d"(edx)
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: "0"(eax),"2"(ecx)
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:);
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return eax;
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}
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/**
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* Get the number of threads the system has.
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*
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* @return Number of threads.
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*/
42+
unsigned int getThreads( void ) {
43+
unsigned int eax = 11, ebx = 0, ecx = 1, edx = 0;
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asm volatile("cpuid"
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: "=a"(eax),
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"=b"(ebx),
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"=c"(ecx),
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"=d"(edx)
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: "0"(eax),"2"(ecx)
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:);
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return ebx;
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}
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/**
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* Get the current thread in use.
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*
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* @return Actual in use.
59+
*/
60+
unsigned int getCurrentThread( void ) {
61+
unsigned int eax = 11, ebx = 0, ecx = 1, edx = 0;
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asm volatile("cpuid"
63+
: "=a"(eax),
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"=b"(ebx),
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"=c"(ecx),
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"=d"(edx)
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: "0"(eax),"2"(ecx)
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:);
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return edx;
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}

‎Practices/P1/sort/thrd-posix.h

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// A set of functions that retrieves some OS parameters.
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// Author: Josue Mosiah Contreras Rocha
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// File: thrd-posix.h
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// Date: 05/02/2020
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// -----------------------------
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// Public interface
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// -----------------------------
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// Functions
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unsigned int getCores( void );
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unsigned int getThreads( void );
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unsigned int getCurrentThread( void );

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