Date: Fri, 10 Apr 2009 14:08:09 +0100 From: Chris Whitehouse <cwhiteh@onetel.com> To: Bob Johnson <fbsdlists@gmail.com> Cc: User Questions <freebsd-questions@freebsd.org> Subject: Re: new package system proposal Message-ID: <49DF44B9.9080303@onetel.com> In-Reply-To: <54db43990904071435h5dc1e854p2e9892ac666aea35@mail.gmail.com> References: <49D76B02.4060201@onetel.com> <54db43990904071435h5dc1e854p2e9892ac666aea35@mail.gmail.com>
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Bob Johnson wrote: > >> - reduced energy use for everyone. > > I think the difference in energy use would be so small as to be > pointless. If I have a system that consumes 75 kilowatt hours per > month, and I spend an extra 0.05 kilowatt hour per month updating > ports, is the difference (less than 1/10 of 1 percent) really > meaningful? I can't even measure my power usage accurately enough to > detect the difference. Convince me to use three liters less hot water > per month, and you will save more energy. How do you get the figures above? I measured electricity use for a typical 2 year old computer (excluding screen) as: - computer idling - 80 watts - computer working hard - 125 watts That's a diff of 45 watts. Suppose normally you use your computer 4 hours a day and it normally takes you 20 hours to upgrade your ports. You start the upgrade while using the computer but you leave it compiling for an extra 16 hours. Thats 4 hours at 45 watts plus 16 hours at 125 watts. Thats 2180 watt hours or over 2 kWh on top of your normal use for one port upgrade. However you jig the figures there is no escaping that cpu cycles use energy. Multiply by the number of times ports are upgraded per computer per year and the number of computers being upgraded and a package system seems like a worthwhile saving. (Thanks Colin Percival et al for freebsd-update, this aspect of it hadn't occurred to me) To complete your comparison if you used electricity to heat 3 litres of water from 15 degC to 55 degC you would use 0.139kWh. Chris
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