Messages in this thread | | | Date | Fri, 06 Jan 2006 18:01:35 +0900 | From | IWAMOTO Toshihiro <> | Subject | Re: [PATCH 6/9] clockpro-clockpro.patch |
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At Thu, 5 Jan 2006 08:32:19 -0500 (EST), Rik van Riel wrote: > > On Thu, 5 Jan 2006, IWAMOTO Toshihiro wrote:
> > In my understanding of CLOCK-Pro, such lapping causes sudden increase > > in the distance between Hhot and Hcold. As that distance is an > > important parameter of page aging/replacement decisions, I'm afraid > > that such lapping would result in incorrect page aging and bad > > performance. > > Hcold only manipulates cold pages, Hhot only manipulates hot > pages and the test bit on cold pages. Having one hand overtake > the other should not disturb things at all, since they both do > something different.
I don't think so. Hhot turns unreferenced hot pages into cold ones, and those are freed if they aren't referenced before Hcold passes. So, the distance between those hands is a sort of "expiry timer" of such pages. The distance also affects aging of newly inserted pages.
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