[ubuntu-uk] Where are we with Green?

Rob Beard rob at esdelle.co.uk
Wed Feb 27 20:55:32 GMT 2008

andy wrote:

> 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.

No problem, I'm in Green mode at the moment with all this work at the 
community centre and Green Month coming up.

> 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?
> Regards,
> Andy

Well, if you had enough memory, there's no reason why you couldn't run 
the entire OS from ram.  I think eventually when the solid state hard 
drives like what they have in the EeePC come down in price then it'll 
save even more money.

I also guess it depends on what you're doing.

An example I would use is from the radio station world...

We had a producer who was using an older PC (Dell Optiplex GX280, 512MB 
memory, 2.8GHz P4 CPU).  He was doing lots of multi track audio 
production which involved processing and effects.  It would take a while 
to do things, plus it was running other tasks in the background.

It would take ages to do anything with the slow machine which took him 
longer to do things and also used a whole load of power (being a power 
hungry CPU).

We replaced his machine recently with an Optiplex GX755 with a Core 2 
2Ghz CPU (dual core) with 1GB ram.  Not only did the enhancements in the 
Core2 architecture speed things up no end, it also saved power.

Another example would be something like the office PCs.  They generally 
run idle most of the time.  They could probably run just as well with 
2GHz Pentium 4 CPU as they could with a dual core Pentium D 820 (2.8GHz) 
as most of the time they just sit idle.


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