Re: RFC: powerd Patch & proposed future changes [wifi tx power]

Aragon Gouveia wrote:
> Rene Schickbauer wrote:
>> Hi!
>>
>>> I think this is a very nice idea, especially the TFT backlight part. It
>>> also might be useful to adjust the WiFi transmit power level according
>>> to battery state. That can also save some power, especially on
>>> portables.
>>
>> Yes, changing the transmit power would be possible. Although 
>> adjusting the
>> transmit power via script on a *mobile* computer is likely to get the 
>> user
>> offline rather quickly.
>>
>> On the other hand, powerd would just run a script. This script could 
>> start a
>> user-written daemon to continually adjust power level.. and when ac is
>> plugged in again, the script kills that daemon. I sincerely doubt 
>> that would
>> save you any amount of power worth mentioning, though but may give you
>> additional troubles. But maybe you could restrict an a/b/g card to 
>> b/g or a
>> and thus save some power.
>
> FWIW, changing transmit power on my Intel 4965 based system made zero 
> difference to overall power consumption.
Changing the tx power is unlikely to save you much.  What you want to do 
is switch between sta mode power save when you switch between AC and 
battery and/or change the PS parameters depending on the power config 
and battery level.  I don't recall if iwn is hooked up properly to 
ifconfig to control power save operation.

FWIW wifi tx power control (TPC) is best used to avoid saturating the rx 
radio when in close proximity.  It's also good to reduce the power so 
you don't splatter adjacent channels (mostly in 2.4GHz).   Some devices 
do this automatically.

    Sam