From owner-freebsd-hackers@FreeBSD.ORG Sun May 8 14:36:05 2005 Return-Path: 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 0BA3816A4E3; Sun, 8 May 2005 14:36:05 +0000 (GMT) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id C570A43D58; Sun, 8 May 2005 14:36:01 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.254.11] (junior-wifi.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.3/8.13.3) with ESMTP id j48Ef8pb021432; Sun, 8 May 2005 08:41:09 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <427E23BA.7000508@samsco.org> Date: Sun, 08 May 2005 08:35:38 -0600 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.5) Gecko/20050218 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Steven Hartland References: <069901c54bfd$2967ba40$7f06000a@int.mediasurface.com><427D5AA0.1080609@withagen.nl><002b01c553be$93a5b790$b3db87d4@multiplay.co.uk> <427E0F77.50006@samsco.org> <001c01c553da$5554e490$b3db87d4@multiplay.co.uk> In-Reply-To: <001c01c553da$5554e490$b3db87d4@multiplay.co.uk> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.8 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on pooker.samsco.org cc: freebsd-hackers@freebsd.org cc: freebsd-current@freebsd.org cc: Willem Jan Withagen Subject: Re: Very low disk performance Highpoint 1820a X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 08 May 2005 14:36:05 -0000 Steven Hartland wrote: > ---- Original Message ----- From: "Scott Long" > > >> Steven Hartland wrote: >> >>> If that where the case it would have been it wouldn't have been >>> 46Mb/s it would have been 543Mb/s, just tested it for you :P >> >> >> The RR1280 cards are really just software RAID cards. All of the parity >> calculations are done by the CPU. I couldn't find much evidence that >> the driver has parity routines that are optimized for the CPU, so it's >> likely doing a very inefficient job at it. > > > According to the documentation this is not the case and the XOR > calcs are done in hardware on the onboard HPT 601. Maybe I'm confused and we are talking about different cards. > >> Changing MAXPHYS is very dangerous, unfortunately. The root of the >> problem is that kernel virtual memory (KVA) gets assigned to each I/O >> buffer as it passes through the kernel. If we allow too much I/O through >> at once then we have the very real possibility of exhausting the kernel >> address space and causing a deadlock and/or panic. That is why MAXPHYS >> is set so low. Your DD test is unlikely to trigger a problem, but try >> doing a bunch of DD's is parallel and you likely will. > > > Thanks for the heads up on this scott I'll do some tests to see that > happens. > N.B. I'm currently using 256K instead of 128K which has the same > performance increase as using 1M. > Note: all tests are being done on i386 not AMD64 due to our requirement > for i386 Linux emulation which it is my understanding is not available when > running AMD64 FreeBSD. Linux/i386 emulation works quite well on FreeBSD/amd64 and is getting better every day. There is active development on it at the moment. Scott