there is a trade-off between memory use and CPU overhead, give an example where increasing the size of virtual memory will improve job throughput. Give an example in which doing so will cause throughput to suffer and explain why this is so. Purchase the answer to view it
The trade-off between memory use and CPU overhead is a fundamental aspect of computer systems and is closely tied to the concept of virtual memory. Virtual memory is a technique used by operating systems to provide an illusion of infinite memory by moving data between physical memory (RAM) and secondary storage (usually a hard disk or solid-state drive). This allows programs to run even if they require more memory than is physically available.
Increasing the size of virtual memory can have both positive and negative effects on job throughput, depending on the specific scenario. Let us consider two examples to illustrate these effects.
In the first example, increasing the size of virtual memory can improve job throughput. Suppose a computer system has limited physical memory available and is running multiple memory-intensive tasks simultaneously. Each task requires more memory than is available in physical memory. In this scenario, the operating system can allocate more virtual memory to each task, allowing them to continue executing without being hindered by insufficient physical memory. This increase in virtual memory size enables a higher level of parallelism, as more tasks can be executed concurrently, resulting in improved job throughput.
However, there are scenarios where increasing the size of virtual memory can cause a decrease in job throughput. Consider a case where a computer system has ample physical memory available, and a specific task frequently accesses a large dataset. If the virtual memory size is increased beyond what is necessary, it can lead to excessive paging. Paging is when the operating system moves data between physical memory and secondary storage to manage memory resources effectively. Excessive paging occurs when the system rapidly swaps data between memory and secondary storage due to the large virtual memory size. This excessive swapping introduces significant CPU overhead, reducing the CPU cycles available for executing the actual task. As a result, the throughput of the task suffers, as more time is spent on memory management operations rather than actual computation.
In summary, increasing the size of virtual memory can improve job throughput in scenarios where there is limited physical memory available and multiple memory-intensive tasks are running concurrently. However, in scenarios where there is sufficient physical memory, excessive virtual memory size can lead to excessive paging and increased CPU overhead, causing a decrease in job throughput. Therefore, it is essential for system administrators and designers to carefully consider the implications of virtual memory size on job throughput and strike a balance that maximizes both memory utilization and CPU efficiency.