Date: Wed, 13 Dec 2000 22:55:48 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Marius Bendiksen <mbendiks@eunet.no> Cc: Julian Elischer <julian@elischer.org>, Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>, arch@FreeBSD.ORG Subject: Re: Even 1GB KVA is not enough, but we have no more space Message-ID: <200012140655.eBE6tmP92001@earth.backplane.com> References: <Pine.BSF.4.05.10012131456100.37018-100000@login-1.eunet.no>
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:> THEORETICALLY it should be possible to put the kernel into a differnt
:> KV space from the processes and give it 4GB.
:> Practically, we'd have to do a lot to do this, and it may effect
:> throughout (page tables loading in and out).
:
:Isn't KV space just system pages (ie kernel adress space)? If so, then making
:the system handle a 4GB KV could be done by maintaining a certain portion of
:the KV space in the user page directory, and switching to the KV page directory
:on demand, at that point removing user pages.
:
:Marius
We're probably not going to ever do anything like this, because
manipulating page directory entries or the whole VM space on a
user->supervisor or supervisor->user transition flushes
the TLB and seriously degrades performance.
-Matt
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