Re: [PATCH] [Fwd: Console locking and blanking]

[Steven Rostedt]

On Tue, 2005-08-16 at 21:55 -0600, Alejandro Bonilla Beeche wrote:
> On Tue, 2005-08-16 at 23:44 -0400, Steven Rostedt wrote:
> > On Wed, 2005-08-17 at 13:29 +1000, Benjamin Herrenschmidt wrote:
> > > On Wed, 2005-08-17 at 11:41 +1000, Benjamin Herrenschmidt wrote:
> > > 
> > > > (I'm blind and I use a braille display. I use those functions to blank 
> > > > my laptop's screen so people don't read it, and hopefully to conserve 
> > > > power.)
> > 
> > At the OLS I learned that the backlight of a laptop (when the screen is
> > black, but still glows) actually spends more wattage than when the
> > screen is lit.  So, unless you actually turn the laptop display off,
> > switching it to black will actually burn the battery quicker.
> 
> This sounds stupid. Who told you this? The actual brightness is the one
> that consumes the most battery.
> 
> Seriously, who told you such thing?
> 

It was one of the speakers during the presentation.  He seemed to know
what he was talking about, in fact, I was caught so off guard by the
statement, I got up and ask him the question again. "Did you say that
the backlight of the laptop takes up more energy than when it is on?"
and he replied "yes"!

I rememeber this being in room C (could be wrong, I went to so many
sessions).  Looking at the program, it could have been "Linux Power
Management" by Patrick Mochel. But I honestly don't remember which
session it was. (I'm CCing him to see if he can clear things up :-)

-- Steve


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