Question

A hard disk with a transfer rate of 10 M bytes/ second is constantly transferring data to memory using DMA. The processor runs at 600 MHz, and takes 300 and 900 clock cycles to initiate and complete DMA transfer respectively. If the size of the transfer is 20 Kbytes, what is the percentage of processor time consumed for the transfer operation?

• A. 0.1%
• B. 0.5%
• C. 5.0%
• D. 1.0%

Answer 1

The correct option is A 0.1%

$Datatransferrate=10Mbytes/sec$
$=10\times 2^{10}Kbyte/sec$

$Sizeoftransfer=20Kbytes$

$10\times 2^{10}\times x\%=20$

$x=\frac{20\times 100}{10\times 2^{10}}$

$x=\frac{200}{1024}=0.19\%$

$or$

$x=0.10\%$