From owner-freebsd-hackers@FreeBSD.ORG Sun Jun 5 21:25:55 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 60ED616A41C for ; Sun, 5 Jun 2005 21:25:55 +0000 (GMT) (envelope-from glenn@antimatter.net) Received: from cobalt.antimatter.net (cobalt.antimatter.net [69.55.224.239]) by mx1.FreeBSD.org (Postfix) with ESMTP id EBC0E43D1F for ; Sun, 5 Jun 2005 21:25:54 +0000 (GMT) (envelope-from glenn@antimatter.net) Received: from glenn-mobile.antimatter.net (cpe-66-27-86-22.san.res.rr.com [66.27.86.22]) (authenticated bits=0) by cobalt.antimatter.net (8.13.4/8.13.4) with ESMTP id j55LPqSG016901 (version=TLSv1/SSLv3 cipher=DES-CBC3-SHA bits=168 verify=NO); Sun, 5 Jun 2005 14:25:53 -0700 Message-Id: <6.1.0.6.2.20050605142135.040c89a0@cobalt.antimatter.net> X-Sender: glenn@cobalt.antimatter.net X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 Date: Sun, 05 Jun 2005 14:24:19 -0700 To: freebsd-hackers@freebsd.org From: Glenn Dawson Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Mailman-Approved-At: Mon, 06 Jun 2005 11:56:48 +0000 Subject: vn(4) performance on 4.11 versus md(4) on 5.4 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Jun 2005 21:25:55 -0000 (I sent this to freebsd-performance yesterday, but that list seems kind of dead, so I'm trying this one. If there's a better place for me to send this, let me know.) I have a number of systems running 4.11 that have file backed virtual disks, each of which contains a jail. I need to start using 5.4 for new servers. The catch is, file backed virtual disks using md(4) seem to be much slower than similar virtual disks on 4.11 using vn(4). vn(4) on 4.11 is about 2.24 times faster than the equivalent setup using md(4) on 5.4. I've posted the results of some tests that I ran at http://www.antimatter.net/md-versus-vn.txt Is this decrease in performance known? Is there something I can do in order to come close to the performance that 4.11 has? I've tried changing some of the parameters of the filesystem on the virtual disk, but the performance didn't change. I can supply more info than what the link above has, if needed. -Glenn