From owner-freebsd-hackers@FreeBSD.ORG Thu Sep 21 14:47:04 2006 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 7050116A47B for ; Thu, 21 Sep 2006 14:47:04 +0000 (UTC) (envelope-from danny@cs.huji.ac.il) Received: from cs1.cs.huji.ac.il (cs1.cs.huji.ac.il [132.65.16.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 341A743D5D for ; Thu, 21 Sep 2006 14:47:00 +0000 (GMT) (envelope-from danny@cs.huji.ac.il) Received: from pampa.cs.huji.ac.il ([132.65.80.32]) by cs1.cs.huji.ac.il with esmtp id 1GQPpL-000IWx-R9 for freebsd-hackers@FreeBSD.ORG; Thu, 21 Sep 2006 17:46:59 +0300 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.2 To: freebsd-hackers@FreeBSD.ORG In-reply-to: <200609210831.k8L8VxvK007258@lurza.secnetix.de> References: <200609210831.k8L8VxvK007258@lurza.secnetix.de> Comments: In-reply-to Oliver Fromme message dated "Thu, 21 Sep 2006 10:31:59 +0200." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Thu, 21 Sep 2006 17:46:59 +0300 From: Danny Braniss Message-ID: Cc: Subject: Re: numbers don't lie ... 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: Thu, 21 Sep 2006 14:47:04 -0000 [...] > But when you perform the buildworld several times (as you > should do when you're benchmarking properly), everything > is already in the RAM disk. If you instead rely on caching > but you don't have enough RAM to hold all of src + obj + > toolchain in RAM, then src (or at least parts of it) will > have to be read from the physical disk again upon each > buildworld. > > By the way, the contents of the RAM disk are _not_ cached > in RAM, so they don't waste RAM twice. That was only a > problem with the old vn(4)/vnconfig(8) in FreeBSD 4. > > Best regards > Oliver you might have a point, but this started when I asked why, two boxes, under similar test gave idential real times, but very different user times. dell-2950 : make -j8 TARGET_ARCH=amd64 buildworld: 24m8.28s real 1h2m59.38s user 16m16.20s sys sunfire : make -j8 TARGET_ARCH=amd64 buildworld: 23m47.69s real 48m53.58s user 13m44.81s sys and SUN X4100: Dual Core AMD Opteron(tm) Processor 280 (2393.19-MHz K8-class CPU) one 70g sas disk (via mpt) -- x 2 DELL 2950: Intel(R) Xeon(TM) CPU 3.20GHz (3192.98-MHz K8-class CPU) 4 sata disks + raid0 (via mfi) -- dual core x 2 cheers, danny