From owner-freebsd-hackers@FreeBSD.ORG Thu Sep 14 12:32:56 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 5C0ED16A412 for ; Thu, 14 Sep 2006 12:32:56 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (lurza.secnetix.de [83.120.8.8]) by mx1.FreeBSD.org (Postfix) with ESMTP id A017D43D45 for ; Thu, 14 Sep 2006 12:32:55 +0000 (GMT) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (uvqlwx@localhost [127.0.0.1]) by lurza.secnetix.de (8.13.4/8.13.4) with ESMTP id k8ECWUdA045192; Thu, 14 Sep 2006 14:32:36 +0200 (CEST) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.13.4/8.13.1/Submit) id k8ECWTXj045191; Thu, 14 Sep 2006 14:32:29 +0200 (CEST) (envelope-from olli) Date: Thu, 14 Sep 2006 14:32:29 +0200 (CEST) Message-Id: <200609141232.k8ECWTXj045191@lurza.secnetix.de> From: Oliver Fromme To: freebsd-hackers@FreeBSD.ORG, danny@cs.huji.ac.il In-Reply-To: X-Newsgroups: list.freebsd-hackers User-Agent: tin/1.8.0-20051224 ("Ronay") (UNIX) (FreeBSD/4.11-STABLE (i386)) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.2 (lurza.secnetix.de [127.0.0.1]); Thu, 14 Sep 2006 14:32:36 +0200 (CEST) Cc: Subject: Re: numbers don't lie ... X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-hackers@FreeBSD.ORG, danny@cs.huji.ac.il List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Sep 2006 12:32:56 -0000 Danny Braniss wrote: > [...] > but the original question stands: > why is the user time between the boxes so different, Because the dual-core Opteron is significantly faster than the (single-core) Xeon, so buildworld takes less (user) CPU time. By the way, certain parts of buildworld make use of both cores, even if you don't use the -j option. If CFLAGS contains the -pipe option (which is the default), various stages of the toolchain can run in parallel (preprocessor, compiler, assembler). > whyle the real time remains the same? Because buildworld is I/O-bound on systems with sufficiently fast processors. Try putting the contents of /usr/src into a RAM disk and repeat the benchmark. The numbers might look a little different then. Of course, you should have sufficient RAM in the machines -- If they're going to swap to the disks, your benchmark won't be happy. I think putting /usr/obj onto a RAM disk is _not_ necessary because of soft-updates, so the processes shouldn't block on writes. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "C is quirky, flawed, and an enormous success." -- Dennis M. Ritchie.