Re: [RFC] Optimization for use-once pages

From: Rik van Riel (
Date: Tue Jul 24 2001 - 11:56:48 EST

On Tue, 24 Jul 2001 wrote:
> On Tue, Jul 24, 2001 at 05:47:30AM +0200, Daniel Phillips wrote:
> > So I decided to look for a new way of approaching the use-once problem
> > that would easily integrated with our current approach. What I came
> > up with is pretty simple: instead of starting a newly allocated page on
> > the active ring, I start it on the inactive queue with an age of zero.
> > Then, any time generic_file_read or write references a page, if its
> > age is zero, set its age to START_AGE and mark it as unreferenced.
> This is wonderfully simple and ellegant.

It's a tad incorrect, though.

If a page gets 2 1-byte reads in a microsecond, with this
patch it would get promoted to the active list, even though
it's really only used once.

Preferably we'd want to have a "new" list of, say, 5% maximum
of RAM size, where all references to a page are ignored. Any
references made after the page falls off that list would be
counted for page replacement purposes.



Executive summary of a recent Microsoft press release:
   "we are concerned about the GNU General Public License (GPL)"

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