Friday, April 3, 2009

A Pagefile allows pages to be recycled

I've been reading an excellent series on resource limits in Windows by Mark Russinovich and ran across some information that's prompting me to change a habit I started many years ago.

After a fresh install of Windows I've always gotten rid of the pagefile on the theory that, with so much RAM installed, I shouldn't have to worry about running out of physical memory. I figured, hard drives are so much slower than RAM that running without a pagefile would wring a little bit of extra performance out of the system.

"Pushing the Limits of Windows: Virtual Memory" makes it clear that there's a downside to not having a pagefile that I hadn't considered. Memory pages that haven't been used in a long time can't be paged out if there's no pagefile. If you reboot frequently then this is probably not an issue but over the past few years I've tended to be far less frequently than in prior years.

Without a pagefile, if I understand correctly, once a page has been allocated to a process that page will never be recycled. To paraphrase a line from The Matrix: Revolution, this represents an ever increasing probability of catastrophic system failure.

So it's back to using a pagefile. But only one that's fixed at 64MB :)

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