Re: VM Requirement Document - v0.0

From: Jonathan Morton (
Date: Thu Jun 28 2001 - 10:21:58 EST

>There is a simple change in strategy that will fix up the updatedb case quite
>nicely, it goes something like this: a single access to a page (e.g., reading
>it) isn't enough to bring it to the front of the LRU queue, but accessing it
>twice or more is. This is being looked at.

Say, when a page is created due to a page fault, page->age is set to
zero instead of whatever it is now. Then, on the first access, it is
incremented to one. All accesses where page->age was previously zero
cause it to be incremented to one, and subsequent accesses where
page->age is non-zero cause a doubling rather than an increment.
This gives a nice heavy priority boost to frequently-accessed pages...

>Note that we don't actually use a LRU queue, we use a more efficient
>approximation called aging, so the above is not a recipe for implementation.

Maybe it is, but in a slightly lateral manner as above.

from:     Jonathan "Chromatix" Morton
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This archive was generated by hypermail 2b29 : Sat Jun 30 2001 - 21:00:19 EST