How to understand buffer swaps
In SAP training materials, it says that buffer swaps occur when buffer content is deleted from the buffer and is replaced by other content. It's no relation at all to the swapping mechanism on OS level.
I am confused about the source and target of buffer swaps. For example, when buffer swaps occur on program buffer(PXA), where will the data in program buffer be put, physical memory?, and where does new data come from? SAP buffers locate on share memory, belong to virtual memory, but virtual memory is the summary of physical memory and OS swap space(or OS paging file). I just remember that extended memory resides on physical memory, don't know whether sap buffers reside on physical too.
For swapping on OS level, I think it's page exchange between physical memory and swap space which locates on disk. Is it right?
Please advise on how to understand buffer swaps and OS swapping. Thanks so much.