Question

A program reads files from disk. It processes each file, then writes the processed file back to disk before reading and processing the next file. Assume that the reading of the file from a local disk takes 5 ms, the processing of the file takes 10 ms, and the writing of the processed file back to the local disk takes 15 ms. How long does it take the program to process 100 files from the local disk? [5 marks] a. b. Suppose the program reads and writes the files from a network drive instead, and assume that it takes 15 ms for the computer's read request to reach this networlk drive, and the same amount of time for the network drive's data to travel back to the computer (a situation that corresponds roughly to a computer in Auckland accessing a network drive in Sydney). How long does the processing of the 100 files take now? [5 marks]

Answer 1

a) to process 1 file from local disk program takes = 5 + 10 + 15 ms = 30ms including read and write time

so to process 100 files it will require = 100 x 30 = 3000 ms or 3 sec

b) in this scenario when we are reading file we add a latency of 15ms for read request to network drive and 15ms for data to reach so reading time is = 30 ms

writing time is still smae as no change metioned in question = 15ms

so total time for one file = 30 + 15 + 10 = 55ms

so for 100 files we get = 100 x 55 = 5500ms = 5.5sec