From owner-freebsd-stable@FreeBSD.ORG Wed Mar 7 21:06:20 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 6BA9916A400 for ; Wed, 7 Mar 2007 21:06:20 +0000 (UTC) (envelope-from matrix@itlegion.ru) Received: from corpmail.itlegion.ru (corpmail.itlegion.ru [84.21.226.211]) by mx1.freebsd.org (Postfix) with SMTP id 2DADE13C4B2 for ; Wed, 7 Mar 2007 21:06:18 +0000 (UTC) (envelope-from matrix@itlegion.ru) Received: (qmail 74983 invoked from network); 8 Mar 2007 00:06:17 +0300 Received: from unknown (HELO Artem) (192.168.0.12) by 84.21.226.211 with SMTP; 8 Mar 2007 00:06:17 +0300 X-AntiVirus: Checked by Dr.Web [version: 4.33, engine: 4.33.5.10110, virus records: 180289, updated: 7.03.2007] Message-ID: <007901c760fc$71e708a0$0c00a8c0@Artem> From: "Artem Kuchin" To: "Fluffles" References: <20070306020826.GA18228@nowhere> <45ECF00D.3070101@samsco.org><20070306050312.GA2437@nowhere><008101c75fcc$210c74a0$0c00a8c0@Artem> <001a01c7601d$5d635ee0$0c00a8c0@Artem> <001801c7603a$5339e020$0c00a8c0@Artem> <20070307105144.1d4a382f@daydream.goid.lan><002801c760e2$5cb5eb50$0c00a8c0@Artem> <005b01c760e6$9a798bf0$0c00a8c0@Artem> <001601c760ee$f76fa300$0c00a8c0@Artem> <45EF2215.2080402@fluffles.net> Date: Thu, 8 Mar 2007 00:06:14 +0300 Organization: IT Legion MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 Cc: freebsd-stable@freebsd.org Subject: Re: Some Unix benchmarks for those who are interesed X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Mar 2007 21:06:20 -0000 ----- Original Message ----- From: "Fluffles" To: "Artem Kuchin" Sent: Wednesday, March 07, 2007 11:35 PM Subject: Re: Some Unix benchmarks for those who are interesed > Artem Kuchin wrote: >>>> Artem Kuchin wrote: >>>> Hmm. what kind of HDD, RAID or whatever are you using? >>>> My raid pretty much sucks. It is build it on the intel motherboard >>>> LSI Megaraid. But i still get 81Mb/sec when doing >>>> dd if=/dev/ar0 of=/dev/null bs=1M >>>> >>>> How much do you get on this? >>> >>> geom_mirror on 2 desktop SATA drives, but the results of dd are >>> pretty low: >>> >>> # dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 >>> 1000+0 records in >>> 1000+0 records out >>> 1048576000 bytes transferred in 17.817686 secs (58850290 bytes/sec) >>> >>> As you can see, results with a single drive are better: >>> >>> # dd if=/dev/ad4 of=/dev/null bs=1m count=1000 >>> 1000+0 records in >>> 1000+0 records out >>> 1048576000 bytes transferred in 16.219518 secs (64649023 bytes/sec) >> >> How is it possible that you get 2x file copy perfomance ? What's the >> matter?! > > If you use dd on the raw device (meaning no UFS/VFS) there is no > read-ahead. This means that the following DD-command will give lower STR > read than the second: > > no read-ahead: > dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 > read-ahead and multiple I/O queue depth: > dd if=/mounted/mirror/volume of=/dev/null bs=1m count=1000 > > You can test read STR best with bonnie (see > /usr/ports/benchmarks/bonnie); or just with DD on a mounted volume. You > should mount with -o noatime to avoid useless writes during reading, or > use soft updates to prevent meta data from taking it's toll on I/O > performance. > Totall disagree. On the following reasons: 1) Read ahead is simply useless when stream-reading (sequential) 1GB of data 2) atime is NOT updated when using dd on any device, atime is related to file/inode operations which are not performed by dd 3) soft update are also useless (no bad, no good) for long sequential read basically, long sequatial reads/write ignore anything but real drive speed (plate on the spindle) if they are performed long enough. I think that 2 times differences is reallty related to seek times. But on the other hand i am sure my HDD have very good seek times. I'll have a chance to check it all on friday. -- Artem