Date: Thu, 08 Jul 2010 13:28:00 -0400 From: Greg Larkin <glarkin@FreeBSD.org> To: David Kelly <dkelly@hiwaay.net> Cc: Roland Smith <rsmith@xs4all.nl>, Jozsi Avadkan <jozsi.avadkan@gmail.com>, FreeBSD Mailing list <freebsd-questions@freebsd.org> Subject: Re: slow down dd - how? Message-ID: <4C360AA0.1060709@FreeBSD.org> In-Reply-To: <20100708170458.GA34226@Grumpy.DynDNS.org> References: <1278604252.12047.13.camel@localhost> <20100708164437.GA21881@slackbox.erewhon.net> <20100708170458.GA34226@Grumpy.DynDNS.org>
next in thread | previous in thread | raw e-mail | index | archive | help
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 David Kelly wrote: > 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. > Indeed someone has, and I ported it a few months back: http://www.freshports.org/sysutils/pmt. Check the "throttle" subcommand. I also use idprio(1) (http://www.freebsd.org/cgi/man.cgi?query=idprio&sourceid=opensearch) to schedule processes that I don't want interfering with the rest of the system. Hope that helps, Greg - -- Greg Larkin http://www.FreeBSD.org/ - The Power To Serve http://www.sourcehosting.net/ - Ready. Set. Code. http://twitter.com/sourcehosting/ - Follow me, follow you -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iD8DBQFMNgqg0sRouByUApARAmsbAJ9ayMlkCUhJpJr0HsPxMmHQ1ToYzgCgrJGX uIeciRHWwaNYrchL4TjYnkA= =NKtY -----END PGP SIGNATURE-----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4C360AA0.1060709>