From owner-freebsd-stable@FreeBSD.ORG Thu Nov 25 07:19:04 2004 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 66EA216A4CE for ; Thu, 25 Nov 2004 07:19:04 +0000 (GMT) Received: from auk1.snu.ac.kr (auk1.snu.ac.kr [147.46.100.31]) by mx1.FreeBSD.org (Postfix) with ESMTP id 01AF743D45 for ; Thu, 25 Nov 2004 07:19:04 +0000 (GMT) (envelope-from spamrefuse@yahoo.com) Received: from [147.46.44.181] (spamrefuse@yahoo.com) by auk1.snu.ac.kr (Terrace Internet Messaging Server) with ESMTP id 2004112516:18:50:719556.29903.2550053808 for ; Thu, 25 Nov 2004 16:18:50 +0900 (KST) Message-ID: <41A58766.8030607@yahoo.com> Date: Thu, 25 Nov 2004 16:19:02 +0900 From: Rob User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.3) Gecko/20041113 X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-stable@freebsd.org References: <41A2C5C0.3080908@yahoo.com> <2566.10.0.0.26.1101241872.squirrel@10.0.0.26> <41A3EA0F.3080500@yahoo.com> In-Reply-To: <41A3EA0F.3080500@yahoo.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-TERRACE-SPAMMARK: YES-__TRSYS_LV__3 (SR:-1.55) (SRN:SPAMROBOT) ----------------- Subject: Re: make -j$n buildworld : use of -j investigated X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Nov 2004 07:19:04 -0000 Rob wrote: > Brian Szymanski wrote: > >> Did you try any machines that used Hyperthreading? I'd be interested to >> see how those machines fare based on the number of logical and real CPUs. >> >> >>> Although people suggest "-j4" as optimal in general >>> case, I have come to a very different conclusion: >>> >>> 1) single CPU with enough RAM (2 GHz, 512 MB) >>> there's no significant speed up in the range >>> "-j1" to "-j9". >>> So "-j1" is as good as "-j9". >> >> >> >> If you went to all that trouble, you might as well post the numbers :-) > > > Time unit is minutes. > > CPU: 2x800 MHz 2000 MHz 333 MHz > RAM: 1024 MB 512 MB 64 MB > -j -------------------------------- > 1 99 50 276 > 2 58 49 291 > 3 58 50 367 > 4 57 50 547 > 5 58 49 > 6 58 50 > 7 57 50 > 8 58 50 > 9 58 50 I have run another test on a 700 MHz, 128 MB PC, and the following equation seems to hold for all my tests. Calculate: time(minutes) * speed(MHz) * nproc / 1000 MHz and if this results in approximately 1, the system is optimized. For example, in the above case, column 1: -j1 : 99 * 800 * 2 / 1000 = 1.5 -j2 : 58 * 800 * 2 / 1000 = 0.928 column 2: -j1 : 50 * 2000 * 1 / 1000 = 1 column 3: -j1 : 276 * 333 * 1 / 1000 = 0.919 another PC: -j1 : 142 * 700 * 1 / 1000 = 0.994 -------------- All PCs have "standard" hardware. Off-the-shelf mainboard, IDE harddisks, nothing special really. All this is done on 5.3-Stable systems and the time listed (in minutes) is for the buildworld only: "make -jn buildworld" Rob.