Question
Which one of the following facilitates transfer of bulk data from hard disk to main memory with the highest throughput?
Official answer and solution
- Official answer
- A
- From
- Official GATE 2022 answer key
Solution
Compare I/O data transfer mechanisms based on CPU involvement and bulk data transfer throughput.
For bulk data transfer from secondary storage (hard disk) to main memory:
- In programmed I/O and polling-based I/O, the CPU is in a busy-wait loop, transferring one byte or word at a time, resulting in significant CPU overhead and low throughput.
- In interrupt-driven I/O, the CPU handles an interrupt service routine for each byte or block transferred, which still involves substantial context-switching overhead.
- In Direct Memory Access (DMA), the DMA controller takes control of the system bus and transfers entire blocks of data directly between the disk buffer and main memory without CPU intervention, generating only a single interrupt upon completion of the entire transfer.
Consequently, DMA-based transfer achieves the highest throughput for bulk data.
Final answer
Option (A)
Common trap
Confusing interrupt-driven I/O with DMA; interrupt-driven I/O still routes data through CPU registers.
The answer is the one in the official GATE answer key. The solution is this site's own explanation.
Source
- Paper
- GATE 2022 Computer Science and Information Technology (CS)
- Question
- 17 of 65
- Section
- Computer Science and Information Technology
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