Power management in F10

[Tore Anderson]

Hello,

I'm a long-time Debian/Ubuntu user who have decided to finally try out 
Fedora.  So I installed F10 (x86_64, KDE version) on my ThinkPad X61s.  
One of the first things I noticed was that my hard drive made clicking 
sounds every few seconds, due to excessive head parking.  The hard drive 
power management feature was not managed by F10, so I submitted a bug 
about that (#473568).

However, as I was playing around with it more, the more I realised that 
Fedora's power management leaves _a lot_ to be desired.  It is barely 
there at all!  Here's a short list over things that I've noticed so far:

Many settings are not adjusted when (dis)connecting mains:
- /proc/sys/vm/laptop_mode
- /sys/class/scsi_host/host*/link_power_management_policy
- /sys/class/net/wlan0/device/tx_power
- Hard drive APM (hdparm -B)
- Various tricks to prevent waking hard drive too often:
  - Increasing dirty_writeback_centisecs and readahead
  - Remounting file systems with -o relatime

Laptop-mode-utils, which handles lot of these settings, is absent.  
Possibly pm-utils is supposed to replace it?  It only seems to control 
/sys/devices/system/cpu/sched_mc_power_savings, though, which makes it a 
very incomplete replacement.

In my opinion, F10 is unsuitable for laptops (at least if you care about 
battery lifetime).  I'd like to help out and improve the situation, 
though, but where do I start?  I'm thinking about submitting power.d 
scripts for pm-utils that'll adjust the knobs I've listed above, but I'm 
don't know if pm-utils is meant to be the preferred «Fedora Way» of 
handling power management or not, seeing how it does almost nothing at 
all right now.  If it isn't, then what is?

Best regards,
-- 
Tore Anderson