Benjamin Pineau

Intel's PowerTOP utility made me aware of the Linux power consumption mess. There's a lot of low hanging fruits here. A short list of things I'll investigate:

• NetworkManager. Freackin' power drain, hard to fix. More on this in a later post.
• SCIM. This one sucks power on all Asians' linux desktops. Bad SCIM, bad.
• Red Hat bug 204948 aka "Userspace sucks (wakeups)"
  
• Ubuntu's misnamed power-management-in-ubuntu blueprint
• thinkpad-keys, in Ubuntu's hotkey-setup. Unneeded with kernel 2.6.22 upward: ensure it's replaced by proper ACPI events handling.
• High Resolution Timers patchset. The "force enable hpet" series makes quite a difference on my ICH4-M system.
  
• Sensible defaults on distros setups. Like AC97 power saving feature, efficient frequency scaling governor, ...
• Why the hell isn't the thinkpad_acpi (formerly ibm_acpi) kernel module autoloaded ?
• Write tools to track relevant things that PowerTOP doesn't show (like block I/O and DMA activity). Systemtap will be of use.

On my X40 laptop, the default Ubuntu Gutsy desktop drains ~14W (thanks to NetworkManager behavior, it can't even enter C3 or C4 ACPI c-states). Manual tweaks brings it down to ~11W: this should be the default setup. Despite Arjan's recent LKML post, there's still room for improvement.