Re: Metrics for comparing power savings of patches...

[Pavel Machek <pavel@ucw.cz>]

On Fri 2008-03-07 12:01:05, Scott Thompson wrote:
> I've seen several patch submissions and comments with varying
> claims of 'power savings' from one level to another on both the 
> linux-pm and powertop lists.
> 
> Standard technique seems to be to plug computer directly into a
> wattmeter and then provide some feedback as to the savings comparing
> one patchgroup to what is currently available.
> 
> Different wattmeters, however, will have different response and 
> accuracy depending on load for instant readings; usually the lower-
> loads (such as laptops) will be less accurate.

notebooks usually have internal wattmeters. cat /proc/acpi/batt*/*/*.

> However, I have seen that most wattmeters do a 'better' job at 
> measuring total wattage over an interval than the 'instant 
> reading'. I advise caution in advertising 'expected savings' for 
> instant readings....
> 
> Also, if anyone knows of any free benchmarks, best practices, or 
> guidelines for trying to do comparative power analysis for patches 
> with wattmeters please let me know.

Intel has something on lesswatts.org.
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