From owner-freebsd-questions@FreeBSD.ORG Thu Jul 8 17:05:08 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4236B1065675 for ; Thu, 8 Jul 2010 17:05:08 +0000 (UTC) (envelope-from dkelly@Grumpy.DynDNS.org) Received: from amavis-smtp.knology.net (amavis-smtp.knology.net [75.76.199.6]) by mx1.freebsd.org (Postfix) with ESMTP id 1A96D8FC15 for ; Thu, 8 Jul 2010 17:05:07 +0000 (UTC) Received: from localhost (amavis-smtp [127.0.0.1]) by amavis-smtp.knology.net (Postfix) with ESMTP id 187DA890F0; Thu, 8 Jul 2010 13:05:06 -0400 (EDT) Received: from smtp12.knology.net ([75.76.199.9]) by localhost (amavis-smtp.knology.net [75.76.199.6]) (amavisd-new, port 10024) with LMTP id rSMUOZR6esMY; Thu, 8 Jul 2010 13:05:04 -0400 (EDT) Received: from Grumpy.DynDNS.org (unknown [24.42.224.110]) by smtp12.knology.net (Postfix) with ESMTP id 160B55200050; Thu, 8 Jul 2010 13:04:53 -0400 (EDT) Received: by Grumpy.DynDNS.org (Postfix, from userid 928) id 676A02841F; Thu, 8 Jul 2010 12:04:58 -0500 (CDT) Date: Thu, 8 Jul 2010 12:04:58 -0500 From: David Kelly To: Roland Smith Message-ID: <20100708170458.GA34226@Grumpy.DynDNS.org> References: <1278604252.12047.13.camel@localhost> <20100708164437.GA21881@slackbox.erewhon.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100708164437.GA21881@slackbox.erewhon.net> User-Agent: Mutt/1.4.2.3i Cc: Jozsi Avadkan , FreeBSD Mailing list Subject: Re: slow down dd - how? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Jul 2010 17:05:08 -0000 On Thu, Jul 08, 2010 at 06:44:38PM +0200, Roland Smith wrote: > On Thu, Jul 08, 2010 at 05:50:52PM +0200, Jozsi Avadkan wrote: > > How can I slow down dd? > > Play with the block size parameter (bs). Smaller block sizes means more > reads. The default is 512 bytes, which is very small. > > > I don't want to slow down the pc, when generating a big file [~40 > > GByte]. I don't think Jozsi wants to burn more CPU cycles, just slow the process. Perhaps to attract less attention? Or interfere less with other processes. Nice(1) is a good start but rtprio(1) is probably where he should look. Also consider that writing a program of your own to serve as a slow pipe shouldn't be very hard. Think it would be a good exercise as an introduction to Unix programming. Simply copy stdin to stdout with a usleep(3) between. Pipe dd through your slowpipe program. Someone else has probably written a slow pipe. I haven't looked. -- David Kelly N4HHE, dkelly@HiWAAY.net ======================================================================== Whom computers would destroy, they must first drive mad.