From owner-cvs-all@FreeBSD.ORG Wed Mar 10 22:41:13 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 645CF16A4CF for ; Wed, 10 Mar 2004 22:41:13 -0800 (PST) Received: from tx1.oucs.ox.ac.uk (tx1.oucs.ox.ac.uk [129.67.1.167]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2CF4643D1F for ; Wed, 10 Mar 2004 22:41:13 -0800 (PST) (envelope-from colin.percival@wadham.ox.ac.uk) Received: from scan1.oucs.ox.ac.uk ([129.67.1.166] helo=localhost) by tx1.oucs.ox.ac.uk with esmtp (Exim 4.24) id 1B1JsW-0008Dd-IC for cvs-all@FreeBSD.org; Thu, 11 Mar 2004 06:41:12 +0000 Received: from rx1.oucs.ox.ac.uk ([129.67.1.165]) by localhost (scan1.oucs.ox.ac.uk [129.67.1.166]) (amavisd-new, port 25) with ESMTP id 31316-06 for ; Thu, 11 Mar 2004 06:41:12 +0000 (GMT) Received: from gateway.wadham.ox.ac.uk ([163.1.161.253]) by rx1.oucs.ox.ac.uk with smtp (Exim 4.24) id 1B1JsW-0008DT-4d for cvs-all@FreeBSD.org; Thu, 11 Mar 2004 06:41:12 +0000 Received: (qmail 26754 invoked by uid 1004); 11 Mar 2004 06:41:12 -0000 Received: from colin.percival@wadham.ox.ac.uk by gateway by uid 71 with qmail-scanner-1.20 (clamscan: 0.67. sweep: 2.18/3.79. Clear:RC:1(163.1.161.131):. Processed in 0.432089 secs); 11 Mar 2004 06:41:12 -0000 Received: from dhcp1131.wadham.ox.ac.uk (HELO piii600.wadham.ox.ac.uk) (163.1.161.131) by gateway.wadham.ox.ac.uk with SMTP; 11 Mar 2004 06:41:10 -0000 Message-Id: <6.0.1.1.1.20040311063721.03e220b8@imap.sfu.ca> X-Sender: cperciva@imap.sfu.ca (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1 Date: Thu, 11 Mar 2004 06:41:06 +0000 To: "Poul-Henning Kamp" From: Colin Percival In-Reply-To: <48348.1078986950@critter.freebsd.dk> References: <48348.1078986950@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/sys mdioctl.h src/sys/dev/md md.c src/sbin/mdconfig mdconfig.8 mdconfig.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Mar 2004 06:41:13 -0000 At 06:35 11/03/2004, Poul-Henning Kamp wrote: >In message <6.0.1.1.1.20040311062306.03f9ade0@imap.sfu.ca>, Colin Percival >writ >es: > > > > Is it really necessary for vnode-backed memory disks to be > >accessed through the filesystem? Why can't md(4) hijack the > >disk blocks which constitute the file (telling the filesystem > >not to touch them, of course) and translate I/O operations > >directly into I/O on the underlying device? > > > >That would be a really complex solution to a problem which should not >exist in the first place :-) Well... yes, but it *would* make sure that data didn't get passed back up to the filesystem layer. And it would probably be faster, which is why I thought of it. Colin Percival