A Level Computer Science OCR Practice Exam

What is disk thrashing typically indicative of?

1. Effective use of virtual memory

2. Inefficient memory usage

3. Low hard drive usage

4. High processing power

The correct answer is: Inefficient memory usage

Disk thrashing is a phenomenon that occurs when a computer's operating system spends excessive time swapping data between physical memory (RAM) and disk storage, instead of executing actual user commands or processes. This typically indicates inefficient memory usage. When the system runs low on RAM, it resorts to utilizing disk space (virtual memory) to offload some of the data. If the demand for memory exceeds the available physical memory, the system increasingly relies on the hard drive to read from and write to the virtual memory. This can result in a constant back-and-forth between the RAM and disk drives, leading to high disk I/O operations and significant degradation in system performance, making it challenging to complete tasks in a timely manner. In this context, the other options do not accurately capture the essence of disk thrashing. For example, while effective use of virtual memory might sound beneficial, it is important to note that thrashing signals a problem with resource allocation rather than effective utilization. Similarly, low hard drive usage does not correlate with thrashing, as thrashing is characterized by high disk activity. Lastly, high processing power does not impact the occurrence of thrashing, because regardless of the CPU's capabilities, if the memory management is inefficient, thrashing will still occur.