[ubuntu-uk] Where are we with Green?

andy andy at zrmt.com
Wed Feb 27 20:04:10 GMT 2008

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Rob Beard wrote:
> andy wrote:
>> Hash: SHA1
>> I've been listening to the BIG GREEN IT DEBATE on the register.. and
>> although it's no where nearly finished (more or less just started)..
>> there's already one point I'd love us to discuss.
>> One of the things that comes up when discussing 'Green motors' is what
>> I'd like to introduce as the Land Rover paradox.
>> "70% of all Land Rovers ever made are still on the road."
>> Once you take into account the energy required throughout the life of a
>> car, including assembly and destruction - are Land Rovers actually that
>> bad for the environment.
>> IMHO, ubuntu may fit into the Land Rover, rather than Toyota Prius
>> category, for a number of reasons.
>> 1) Power Management - where are we at with ubuntu at the moment?  My
>> perception (this will/may be wrong) is that much of the onboard power
>> management is managed through propreitary code, therefore ubuntu
>> performs worse that XP.. par example (but much better than Vista.. on a
>> hunch).
> My dual core 'Pentium Dual Core' is happily running at 1.2GHz at the 
> moment (slowed down from 1.8GHz), it's independent per core too.  That's 
> all controlled by the Powernow Daemon...
> Here's the output from powernowd --help
> "PowerNow Daemon v0.97, (c) 2003-2005 John Clemens
> Daemon to control the speed and voltage of cpus.
> This is a simple client to the CPUFreq driver, and uses
> linux kernel v2.5 sysfs interface.  You need a supported
> cpu, and a kernel that supports sysfs to run this daemon."
> Sounds to me like it's GPL'd.
> It is controlled by Powernowd too, when I tried to overclock my CPU to 
> around 3GHz it kept going back to 1.8GHz/1.2GHz until I disabled 
> powernowd which in turn disabled the power saving.
> That's better than my desktop PC at work running XP which sometimes 
> sounds like a jet engine taking off (it's a Dell Optiplex GX620 with a 
> Pentium D 820 (2.8GHz) with power saving turned off in the BIOS).
>> 2) Re-use.  Ubuntu saves having to re-buy PCs... However, if the
>> efficiency of the new PC means that it'll use less energy, surely
>> there's an argument that upgrading the hardware is more environmentally
>> efficient  - we need some better data to support the ubuntu approach (if
>> there is indeed one).
> Ubuntu can be used in a client/server environment just like Windows 
> 2000/2003 Server.  This is what I'm doing at a local community centre in 
> Exeter.  We're using a fairly mid spec Dell PowerEdge server with a new 
> Intel Xeon Quadcore CPU (2.4Ghz) which will run Ubuntu (or possibly 
> Edubuntu) with LTSP.  The client machines are old K6/2 450 machines 
> which according to the AMD specs use no more than about 36 watts.  Add 
> on the fact that they run completely over the network (no hard drives, 
> no optical drives) they don't have any moving parts (apart from the CPU 
> & PSU fans) and save energy.  They'll be attached to 19" TFT monitors.
> I'd say they'd use less than my desktop PC with it's hard drives and DVD 
> drive in there.
>> 3) Linux versus MS.  Is there anything to suggest that linux boxes are
>> more power efficient.  This doesn't have to be at a hardware/software
>> level either.  More about policy and application.  Linux boxes don't
>> crash, so we never shut them down.. meaning they're never off.  Discuss.
> Not sure on that, I'd say efficiency wise, they're probably about the 
> same.  I guess you could argue that Vista with all it's fancy effects 
> requires a fairly decent spec CPU and graphics card whereas Ubuntu will 
> run it's fancy effects on a much lower spec machine.
> With regards to never shutting the machines down, it depends on the 
> user.  Some people leave their machines on due to lazyness (I can think 
> of a couple of people at work who do this), others leave them on because 
> they run background apps.  I guess both Linux and Windows when idle will 
> use much less power plus put the screens into a standby mode.
> Not sure if anyone is aware, but next month is Green Month, at least it 
> is on the One Network of radio stations 
> (http://commercial.gcapmedia.com/index.php?id=8 - Gemini in Devon, BRMB 
> in Birmingham, Red Dragon in Cardiff etc).
> In the stations we're trying to save energy by turning PCs off 
> automatically at night (this is done through Active Directory), enabling 
> power saving on newer PCs which support it, reminding everyone to turn 
> off their monitors when not in use, combining PCs (such as legal logging 
> machines which need to log output 24/7, these are being combined in some 
> cases from two PCs to one), and even in some extreme cases turning off 
> all the lights (including the lights in the toilet even when someone is 
> in there).
>> I'm coming in at a tangent, but would be interested to hear other
>> people's perceptions of the 'Green-ness' of ubuntu - and some input from
>> people who can give hard facts on the performance of ubuntu power
>> management.
> See comments above.
> When we've installed the LTSP system at the community centre in Exeter 
> I'm going to measure the power usage of the single terminals and the 
> whole installation (server, terminals, switches etc) and compare them to 
> a regular 1 to 2 year old desktop system running XP, it will be 
> interesting to see how it compares.
> Rob


I thought I was asking alot - but this is exactly the response I was
hoping for.  Thanks for taking the time to fill it in.

The only one point that I want to analyse is the cpufreq/powernowd.  One
of the comments made during the debate, was that (power consumption)
versus (cpu % use) wasn't directly proportional.  The difference that
made is that dropping to 50% processor power may reduce power
consumption by 30%.. however, should the processor be running at 100%
then it halves the time taken to compute.. whilst only losing 30%
savings on power.

If we put that in a hypothetical situation..

1hours worth of 100% cpu computation.  saying that the PC uses 100 units
of elecricity over an hour.

for 1 hour at 100% cpu, it'll cost 100 units of electricity.

for 2 hours at 50% cpu, it'll then use 140 units of electricity.

Of course, in the real world, this situation isn't comparable, as we use
computers to run overlapping and simultaneous tasks, many of which use
little computing power but rely solely on user input (word processing,
accounting .etc).  However, there are some situations when this would be
relevant I guess..

I think I'm right in suggesting that S.M.A.R.T hard disks are spun down
and the relevant memory copied to RAM to save power to the hard disk -
but are there other places that ubuntu can help save power throughout
your entire PC.. rather than just the CPU?


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