From owner-freebsd-questions@FreeBSD.ORG Tue Nov 23 06:47:59 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1D40B16A4CE for ; Tue, 23 Nov 2004 06:47:59 +0000 (GMT) Received: from p15140542.pureserver.info (papendorf-se.de [217.160.222.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id D646943D2D for ; Tue, 23 Nov 2004 06:47:57 +0000 (GMT) (envelope-from freebsd@nagilum.org) Received: from localhost (localhost.localdomain [127.0.0.1]) by p15140542.pureserver.info (Postfix) with ESMTP id 5518F2F4117; Tue, 23 Nov 2004 07:47:56 +0100 (CET) Received: from p15140542.pureserver.info ([127.0.0.1]) by localhost (p15140542 [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 17897-10; Tue, 23 Nov 2004 07:47:55 +0100 (CET) Received: from cakebox.homeunix.net (unknown [217.188.235.161]) (using TLSv1 with cipher EDH-RSA-DES-CBC3-SHA (168/168 bits)) (No client certificate requested) by p15140542.pureserver.info (Postfix) with ESMTP id CD69F2F405B; Tue, 23 Nov 2004 07:47:54 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by cakebox.homeunix.net (Postfix) with ESMTP id 240EB3028A5; Tue, 23 Nov 2004 07:47:47 +0100 (CET) Received: from cakebox.homeunix.net ([127.0.0.1]) by localhost (cakebox.tis [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 83049-09; Tue, 23 Nov 2004 07:47:13 +0100 (CET) Received: from [10.1.1.4] (scorpio.tis [10.1.1.4]) by cakebox.homeunix.net (Postfix) with ESMTP id 5B3B5302893; Tue, 23 Nov 2004 07:46:58 +0100 (CET) Message-ID: <41A2DCE5.9040608@nagilum.org> Date: Tue, 23 Nov 2004 07:47:01 +0100 From: Nagilum User-Agent: Mozilla Thunderbird 0.9 (Macintosh/20041103) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rob References: <41A2A7A2.3040102@yahoo.com> <41A2B3BB.3020108@yahoo.com> In-Reply-To: <41A2B3BB.3020108@yahoo.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at cakebox.homeunix.net X-Virus-Scanned: by amavisd-new at papendorf-se.de cc: FreeBSD Subject: Re: make -j$n buildworld : use of -j investigated X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Nov 2004 06:47:59 -0000 The idea behind the speedups by using n>number of CPUs is that you use unused CPU cycles during disk activity. Obviously this works only on systems which use 'low CPU usage storage' such as SCSI, firewire or more prominently NFS for the sources. Of cause this also assumes you don't have any performance penalties due to increased swap usage... So in a 'normal' IDE environment it probably wont make a difference. Regarding your test, I'd say don't trust your results unless you have rebootet the machine betweeen the tests, otherwise the cache will mess up your results. Kind regards, Alex. Rob wrote: > Laurence Sanford wrote: > >> Rob wrote: >> >>> ---------------------------------------- >>> >>> With these simple tests, I come to the conclusion that >>> "make -j$n buildworld" is best with n = number of CPUs. >>> Does that make sense? >>> >>> Rob. >> >> >> This is what I've been telling people and using myself for years. >> However, I've been shot down on this several times, so I just leave >> everyone alone and let them do their own thing. You and I will be >> getting it done a little faster though. > > > Not really faster, but higher values do not make a difference, > well, as long as the extra processes do not force the use of > swap. Intensified swapping because of a high -j value slows > down the build considerably. > > I don't understand why this is reason for debate. My test has > obvious results on various of my PCs, and was very quickly done: > I wrote a script with a loop that built the world again and > again, doing a 'touch' to a file immediately before and after > the build. Got all my data within a day or so. > > Rob. > > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org"