Question

An i/o device transfers a data 10mb/s over a bus which is capable of sending the data at a rate 100mb/s. Consider a processor operates at 200mhz, and it takes 100 clock cycles to handle each dma request. Suppose 8kb blocks of data has been transferred between i/o and main memory then calculate fraction of cpu time handling of the data transfer with dma?

Answer 1

The fraction of CPU time handling of the data transfer with DMA can be found out for this question by first understanding the data transfer process with DMA (Direct Memory Access).

Direct memory access (DMA) is a process that helps an input/output (I/O) device to receive or send data directly from or to the main memory of a computer.

It helps in bypassing the CPU so that the memory operations speed can be enhanced.

The complete process is taken care of by a chip that is called the DMA controller (DMAC).