[Gllug] Have recent kernels improved power consumption

[James Courtier-Dutton]

2009/12/14 John Winters <john at sinodun.org.uk>:
> I have an Acer Aspire One netbook on which I ran Lenny (2.6.26) to begin
> with.  It settled down to an estimated (and apparently fairly accurate)
> battery life of about 1 hour 45 minutes.
>
> Recently I've upgraded it to Squeeze (2.6.30) and I've noticed that the
> estimated battery life seems to have increased to about 2 hours 30
> minutes.  I actually put it to the test last night by leaving it
> running, and although I didn't run the battery right down, it certainly
> seemed to be on course to last significantly longer than before.
>
> I'm wondering why.  Have there been improvements to power management in
> recent kernels?  Or improvements to ancillary bits?  I presume it's not
> just that the battery has suddenly got better.
>

Recent Linux kernels have made great advances in power management.
It has moved from everything being on all the time, to devices only
being powered on when needed.
There are still improvements to be made, but things are definitely
getting better.
For example, if no sound is being played, Linux can automatically turn
off the sound chip and sound amp.
Previously, it left the chip and amp at full power.

If one is playing a DVD, previously, it would run the DVD player at
full 4x or 8x or 16x speed, even though the DVD playing only needs 1x
speed.

All sorts of minor improvements are being made with each mainline
kernel release and these releases happen every 3 months.

Kind Regards

James
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