Swapping | Computer Science
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Swapping is the process of exchanging memory pages between main memory and secondary storage, such as a hard disk. There are three types of swapping that occur. When memory becomes full, inactive processes are swapped out to disk to free up space, and are swapped back in when needed. The first UNIX systems constantly monitored free memory and swapped out processes to disk when levels fell below a threshold. Swap space is used on Linux when RAM is full, with inactive memory pages moved to the swap file to free up space. The swap cache helps avoid race conditions when processes access pages being swapped by collecting shared pages that have been copied to swap space.
Swapping | Computer Science
- 2. Swapping is the process of exchanging pages, segment of memory and values to another location. It occurs in three types. A process can be swapped temporarily out of memory to a backing store, and then brought back into memory for continued execution, here backing store is the fast disk large enough to accommodate copies of all memory images for all users and must provide direct access to these memory images. The first UNIX system kernels monitored the amount of free memory constantly. When it became less than a fixed threshold, they performed some swapping out. This activity consisted of copying the entire address space of a process to disk. Conversely, when the scheduling algorithm selected a swapped – out process, the whole process was swapped in from disk.
- 5. Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. The swap cache is crucial to avoid race conditions among processes trying to access pages that are being swapped. The swap cache collects shared page frames that have been copied to swap areas. It does not exist as a data structure on its own; instead, the pages in the regular page cache are considered to be in swap cache if certain fields are set.
- 6. Swap area
- 7. Swap cache
- 8. This was just a summary on Swapping. For more detailed information on this topic, please type the link given below or copy it from the description of this PPT and open it in a new browser window. www.transtutors.com/homework-help/computer-science/operating-system/memory- management/swapping/