[mythtv-users] Quick opinions

Brian Wood beww at beww.org
Sat May 30 17:32:09 UTC 2009

On Saturday 30 May 2009 11:22:07 Andrew Burgess wrote:
> On Sat, 2009-05-30 at 13:13 -0400, Raymond Wagner wrote:
> > Andrew Burgess wrote:
> > > So the beefier 95w one uses less energy for a given amount of work
> >
> > How did you come to that conclusion?
> If it ran twice as fast at twice the power it would only run half as
> long so use the same energy (energy = power * time). But it runs more
> than twice as fast so would run less than half as long so less energy.

True, but Myth systems tend to spend a lot of time idling. If the faster CPU 
consumes more power at idle, then the overall situation might not be so rosy.

I doubt that you can reduce things to such a simple case anyway, it would 
depend on what kind of work is being done. The manufacturers specs on this 
sort of thing tend to use jobs that showcase the parameters being pushed. 
Integer vs. floating point math is an example.

It might be a case of are you willing to burn more power at idle or 
low-processing type jobs in exchange for getting the occasional high-load 
task completed faster.

Then you would have to consider the effectiveness of the clock-down schemes 
for both CPUs, in the specific cases you are using.

There are always trade offs to be taken into consideration. If one of those 
CPUs was actually "better" in all cases AMD would sell only that one.

beww at beww.org

More information about the mythtv-users mailing list