Subject: Re: iwi firmload annoyance
To: None <current-users@netbsd.org>
From: Garrett D'Amore <garrett_damore@tadpole.com>
List: current-users
Date: 08/13/2006 08:39:54
oliver gould wrote:
> On 2006-08-13 13:07 -0500, Mark Kirby wrote:
>  
>   
>> iwi(4) uses firmload(9) to load firmware images. You no longer need to
>> use iwictl(8) to load the firmware. [Nick Hudson]
>>     
>
> This is a welcome change.  Well, mostly..  Is there any way to _un_load
> the firmware?  Being unable to turn the radio off is pretty wasteful of
> battery power, and therefore pretty annoying for me.
>
> That is, unless I'm totally off-base here.  I assume that
>   $ iwictl iwi0 -r
>   Radio is ON
> means that the wireless card is using power.
>
>   

In the grand scheme of things, wireless card power consumption (for most
devices at least) is pretty minimal.  For non-MIMO devices, figure that
_transmit_ power is ~100-200mW.  I'd be surprised if it made much
difference in the grand scheme of things on a typical laptop.  On many
laptops, the single biggest power consumer is the backlight.  On high
performance units it is often the CPU or the GPU.  The WLAN chipset is
usually barely noticeable.

(For example, a WLAN chipset might use ~.5W, but your processor probably
uses ~20W unless you have a particularly low power unit.)

All the numbers above are swags, but the qualitative analysis is based
on actual experience with Sun Ray thin-client technologies.  Even with
those extremely low power units, it was not considered worth the
engineering effort to do the power saving stuff for WLAN, mostly because
the consumption was so small (the power draw from the backlight dwarfed
the 802.11 chipset).

-- 
Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
http://www.tadpolecomputer.com/
Phone: 951 325-2134  Fax: 951 325-2191