Pagefile vs. swapfile (WinXp SP1)

Topic

New Reply

What is (or is there?) a difference between a Swapfile and a Page file in WinXP? I’ve thought they are one and the same but an app author is telling me no. Since his English isn’t very good, it is proving difficult to communicate. He says the differences are explained in the MS SDK. Can I access the SDK online? Any help of pointers on this appreciated…

Reply | Quote

Replies

They are one and the same. Swap, meaning swapping from memory to disk and back, and page as in memory pages. The app author may be misunderstanding what you’re asking, but rest assured – it’s all the same thing: a space allocated on the hard drive for use as “reserve” memory.

Reply | Quote

See also Memory Architecture in Microsoft Software Developer Network Library.
“…In a virtual memory system, the operating system creates a pagefile,
or swapfile…”

Reply | Quote

The memory management architecture in Windows NT was based on the design for VMS, where pagefiles and swapfiles were subtly different. A pagefile was used to store small parts of a process address space, whereas a swapfile stored the whole thing.

StuartR

Reply | Quote

Aha, there’s the DEC background! I imagine this was David Cutler’s handiwork. Are you aware of any differences under the NT platform? I have always presumed the terms to be interchangeable with the NT architecture, since it maintains only once such file (that I’ve ever seen).

Reply | Quote

Stuart – Your explanation sounds similar to how IBM’s MVS OS works (or used to). A whole address space was SWAPPED out while individual 4k pages of an address space or something were PAGED out.

In this case, it looks like the author is calling swapfile the amount of space used on the physical disk page file and his pagefile metric is the combination of total disk page file size + RAM. Kind of weird usage…

Reply | Quote