Subject: Re: Do some disk accesses miss the UVM?
To: Chuck Silvers <>
From: Perry E. Metzger <>
List: tech-kern
Date: 01/26/2002 19:12:13
Chuck Silvers <> writes:
> > > actually the generational idea isn't a replacement for the knobs.
> >
> > Absolutely, but *every* policy does. The best part of the research of
> > the last 30 years on the subject is the realization that even if you
> > have a psychic computer that knows what the entire future of page use
> > will be, in the most general case it is still extremely
> > computationally expensive to determine what pages to evict.
> of course, but that's only marginally related to what I said.
> or are you implying that using information about the type of data
> that pages contain in the replacement code is necessarily too
> computationally expensive, or that the class of applications
> that require it is unimportant?  I don't agree with that.

I'm implying that knobs might not be needed in practice if we have the
right page replacement algorithm, even though there will always be
pathalogical cases where they are needed.

Perry E. Metzger
NetBSD Development, Support & CDs.