From owner-freebsd-hackers Fri Dec 19 06:23:57 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id GAA19938 for hackers-outgoing; Fri, 19 Dec 1997 06:23:57 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from word.smith.net.au (ppp6.portal.net.au [202.12.71.106]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id GAA19925 for ; Fri, 19 Dec 1997 06:23:45 -0800 (PST) (envelope-from mike@word.smith.net.au) Received: from word (localhost [127.0.0.1]) by word.smith.net.au (8.8.8/8.8.5) with ESMTP id AAA00414; Sat, 20 Dec 1997 00:47:34 +1030 (CST) Message-Id: <199712191417.AAA00414@word.smith.net.au> X-Mailer: exmh version 2.0zeta 7/24/97 To: Michael Hancock cc: John-Mark Gurney , freebsd-hackers@FreeBSD.ORG Subject: Re: converting drivers to dynamic memory... In-reply-to: Your message of "Fri, 19 Dec 1997 16:18:42 +0900." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sat, 20 Dec 1997 00:47:33 +1030 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > > > Forget the btree model; it's not going to fly in the face of a direct > > > reference approach. ... > > when did I ever say that we should in the long run choose using a > > btree over the "correct" way to do it?? I only said it would require > > Hashing for example is very good in the kernel, even in cases where you > think btrees would be better. The reasoning is along the lines of what > Koshy was talking about. If you can abstract things well enough so that > you can make a change later on very easily, by all means carry on. > Someone will find a use for your Btrees elsewhere most likely. ... but of course dereferencing a pointer (hardly) requires any parallelisation. Why go to all this complexity when all you are interesting in doing is taking an opaque token and obtaining the address of a (reasonably non-motile) structure? Perhaps I'm missing something; let's take the opposite tack. What advantages (in real terms) do we gain by storing the address of the control structure in some fashion and then requiring a token in order to obtain it? Is this advantage significant in the face of the not insubstantial performance penalties? mike