[ltp] Thinkpad T61, Ubuntu, cpu scaling

[Henrique de Moraes Holschuh]

On Thu, 16 Jun 2011, Alessandro Crismani wrote:
> Il giorno gio, 16/06/2011 alle 11.47 +0200, Yves-Alexis Perez ha
> scritto:
> > On jeu., 2011-06-16 at 10:06 +0100, Alessandro Crismani wrote:
> > > Hi,
> > > 
> > > Could you please elaborate a little more on the issue. Every time I've
> > > read about battery management it was said to remove it when on AC and to
> > > store it in a "cold" place (not fridge cold, but not warm either). The
> > > reasoning behind this, as I was told, is beacuse the main cause of
> > > battery life loss is heat, which may be high on laptops bottom surfaces.
> > > Not because of constant charging (which is solved by thresholds as you
> > > suggested).
> > 
> > Put the battery in the fridge when not in use, yes.
> 
> Well, I store it in a wardrobe, still cold enough, the fridge seems
> overkill :)

The target is ~15°C, 10°C is also good, but be _careful_ to never allow it
anywhere close to freezing.  And do it with the battery at ~40% charge.

> > Henrique :)
> 
> Makes sense!

Eh, don't give me the credit for the AC adapter thing, someone else
discovered it and even tracked it down to the EC register that warns us of
an underpowered AC adapter :-)

> > cases (bios detects a 65W adaptor and no battery for example), the bios
> > (or the EC, I'm not sure) will limit the CPU to only the lowest
> > frequencies to prevent power loss.

The EC tells the BIOS of the fact.  The BIOS publishes ACPI info about the
limit, and recent Linux tries to obey it.

> I just wanted to know if there were other reasons for keeping the
> battery around besides the power consuption being too high in some
> cases.

None that I know (on a ThinkPad).  However, a notebook is NOT obligued to
work without a battery as a rule, it is conceivable that some notebooks will
just not work right without a battery.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh