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SubjectRe: Availability of kdb
On Mon, 11 Sep 2000, Jamie Lokier wrote:
> Rik van Riel wrote:
> > The main difference between Linux and Netware here is the
> > fact that Linux has a real userland, which can touch the
> > pages on its own without going through the kernel.
> >
> > This causes "spontaneously" dirtied or accessed pages,
> > meaning that we really want to use the hardware bits ...
>
> Of course you don't _have_ to do things that way with a real
> userland. You can take page faults and update your own bits. I
> think some of the ports actually do this.

Meaning you have to blindly unmap pages and see if they get
faulted back in again. I believe you need to do this trick
with the VAX (and OpenBSD and NetBSD still use this method).

> But we prefer the hardware, even though in some cases
> software-driven faults give better guidance to the paging
> heuristics.

The difference is a locked cycle vs. handling a page fault.
This isn't a very hard choice to make ;)

regards,

Rik
--
"What you're running that piece of shit Gnome?!?!"
-- Miguel de Icaza, UKUUG 2000

http://www.conectiva.com/ http://www.surriel.com/

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