Managing Discardable Pages with an External Pager

We have designed and implemented an external pager that: (1) receives information regarding discardability of pages from the client such as a garbage collector for functional programming languages, (2) saves and restores only non-discardable pages and (3) influences page-replacement by pre-flushing discardable pages. In a general purpose operating system dirty pages are typically saved to disk and then restored from disk even when the application may not care about the contents of those pages. For example, copying garbage collection used in functional programming languages generates many pages that are dirty but discardable. Using the external pager to manage the discardable pages we observed that elapsed times for some applications decreased by as much as a factor of 6.