ibbotson@motcid.UUCP (Craig Ibbotson) (07/25/90)
I have a question I was hoping an OS/2 expert might be able to answer for me. My understanding is that OS/2 uses a demand paging scheme, and advertises it uses the Least Recently Used (LRU) algorithm as its page replacement strategy. However, systems rarely, if ever, use a true LRU implementation and generally implement an approximation of the LRU algorithm; a true LRU algorithm would require timestamping each page. Looking at the memory layout for a page, I see each page has a dirty bit and an accessed bit. This makes me think they are using the Not Used Recently (NUR) approximation to the LRU algorithm, but I cannot find this documented anywhere for certain. Does anyone out there know if OS/2 uses the NUR approximation to the LRU algorithm? If it doesn't use NUR, what does it use? Thanks in advance - Craig