From owner-freebsd-arch Wed Dec 13 22:55:52 2000 From owner-freebsd-arch@FreeBSD.ORG Wed Dec 13 22:55:51 2000 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from earth.backplane.com (placeholder-dcat-1076843399.broadbandoffice.net [64.47.83.135]) by hub.freebsd.org (Postfix) with ESMTP id 2E9BF37B400 for ; Wed, 13 Dec 2000 22:55:51 -0800 (PST) Received: (from dillon@localhost) by earth.backplane.com (8.11.1/8.9.3) id eBE6tmP92001; Wed, 13 Dec 2000 22:55:48 -0800 (PST) (envelope-from dillon) Date: Wed, 13 Dec 2000 22:55:48 -0800 (PST) From: Matt Dillon Message-Id: <200012140655.eBE6tmP92001@earth.backplane.com> To: Marius Bendiksen Cc: Julian Elischer , Seigo Tanimura , arch@FreeBSD.ORG Subject: Re: Even 1GB KVA is not enough, but we have no more space References: Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :> 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 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message