From owner-freebsd-current@FreeBSD.ORG Mon Aug 20 20:42:35 2007 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EC19D16A420 for ; Mon, 20 Aug 2007 20:42:35 +0000 (UTC) (envelope-from se@FreeBSD.org) Received: from spacemail2-out.mgmt.space.net (spacemail2-out.mgmt.space.net [194.97.149.148]) by mx1.freebsd.org (Postfix) with ESMTP id 7A83613C491 for ; Mon, 20 Aug 2007 20:42:35 +0000 (UTC) (envelope-from se@FreeBSD.org) X-SpaceNet-SBRS: None X-IronPort-AV: E=Sophos;i="4.19,285,1183327200"; d="scan'208";a="33087131" Received: from mail.atsec.com ([195.30.252.105]) by spacemail2-out.mgmt.space.net with ESMTP; 20 Aug 2007 22:12:51 +0200 Received: from [192.168.0.12] (p5087A28C.dip0.t-ipconnect.de [80.135.162.140]) (Authenticated sender: se@atsec.com) by mail.atsec.com (Postfix) with ESMTP id C7ED47209ED; Mon, 20 Aug 2007 22:12:50 +0200 (CEST) Message-ID: <46C9F5C0.6000209@FreeBSD.org> Date: Mon, 20 Aug 2007 22:12:48 +0200 From: Stefan Esser User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Max Laier References: <200708170939.l7H9diEk054469@lurza.secnetix.de> <20070819163934.V568@10.0.0.1> <20070820103424.GG1164@turion.vk2pj.dyndns.org> <200708202058.39565.max@love2party.net> In-Reply-To: <200708202058.39565.max@love2party.net> X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: Peter Jeremy , freebsd-current@freebsd.org, Jeff Roberson Subject: Re: Why we don't use bzip2 in sysinstall/rescue? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Aug 2007 20:42:36 -0000 Max Laier schrieb: > With an amd64 world(236M) tar'ed together with -czf / -cyf respectively I > get the following input bandwidth numbers (gathered via dd > if=amd64.t{g,b}z of=/dev/stdio | {g,b}zcat > /dev/null): > > hw.model: Intel(R) Pentium(R) 4 CPU 2.00GHz: > x bz + gz > N Min Max Median Avg Stddev > x 13 1411432 1554463 1544446 1521445.7 50394.705 > + 13 13391136 13847045 13804007 13726781 138363.27 Instead of measuring data rates on the input side (compressed) I think what matters is the output data rate, since that is what needs to be written to disk during an installation. If I assume a compression by a factor of 4 for bzip2, the data rate will be some 6MB/s after decompression on a P4/2GHz and 14MB/s on the Opteron 275. I have measured an P3/733 to deliver 3.25MB/s for bzip2 (and 40MB/s for gzip with a compression of about 1:3.5). > Difference at 95.0% confidence > 1.22053e+07 +/- 84296.2 > 802.22% +/- 5.54053% > (Student's t, pooled s = 104125) > > hw.model=AMD Opteron(tm) Processor 275: > x fast.bz + fast.gz > N Min Max Median Avg Stddev > x 10 3429556 3889574 3449869 3525725.6 169675.46 > + 10 41967910 46046387 45944662 45490300 1257435.8 > Difference at 95.0% confidence > 4.19646e+07 +/- 843005 > 1190.24% +/- 23.9101% > (Student's t, pooled s = 897200) > > So it seems that bzip2 will indeed be bound to CPU - at least when > installing from CD. netinst over the internet is a different story, > though. Since lots of small files are written, we have to consider the transaction rate of the disk and file system being written to. And while 3MB/s is a little low, 6MB/s does not look unreasonable and 14MB/s is definitely sufficient to make the target disk drive become the limiting component (except when you install to a RAM disk or to a RAID storage system with gigabytes of cache ;-) Regards, STefan