Implement a program to measure the impact of application-level buffer sizes on read time. This involves writing to and reading from a large file (say, 2 GB). Vary the application buffer size (say, from 64 bytes to 4 KB). Use timing measurement routines (such as gettimeofday and getitimer on UNIX) to measure the time taken for different buffer sizes. Analyze the results and report your findings: does buffer size make a difference to the overall write time and per-write time?

Input file: input.txt

Output file: output.txt

input.txt is a text file of 500 MB.

CODE:

#include <stdio.h>

#include <time.h>

#include <stdlib.h>

#include <fcntl.h>

#include <sys/time.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

double count = 0; // to keep the count of writes

// function which reads from input.txt and writes to output.txt

void fun(int* file_in, int* file_out, int BUFF_SIZE)

{

char *buff = (char *)malloc(BUFF_SIZE*sizeof(char));

while(read(*file_in, buff, BUFF_SIZE) != 0)

{

write(*file_out, buff, strlen(buff));

count++;

}

}

int main(int argc, char* argv[])

{

if(argc == 1)

{

printf("Usage: ./program.c [ buff_size(in bytes) ]\n");

return 0;

}

int file_in,file_out; // input and output file pointers

file_in = open("input.txt",O_RDONLY);

if(file_in == -1)

{

printf("Error while open input.txt \n");

return 0;

}

file_out = open("output.txt",O_WRONLY);

if(file_out == -1)

{

printf("Error occured while opening output.txt\n");

return 0;

}

struct timeval t1, t2; // for capture time

double elapsedTime;

// start timer

gettimeofday(&t1, NULL);

// do something

// ...

fun(&file_in, &file_out, atoi(argv[1]));

// stop timer

gettimeofday(&t2, NULL);

// compute and print the elapsed time in millisec

elapsedTime = (t2.tv_sec - t1.tv_sec)*1000.0; // sec to ms

printf("Overall write time: %lf ms\n",elapsedTime);

printf("Per write time: %lf ms\n", elapsedTime/count);

return 0;

Explanation:

Please see attachment for output

if you suspect that your immediate supervisor, department manager, or company is engaging in something unlawful you must do your best to end the misconduct immediately while also protecting yourself, your livelihood, and your family’s future.