Power consumption

Posted Apr 26, 2010 20:58 UTC (Mon) by pr1268 (guest, #24648)
In reply to: Power consumption by corbet
Parent article: The cpuidle subsystem

Funny that cpuidle doesn't exist in that directory on my home PC (Slackware 12.2 running vanilla kernel 2.6.31.13). Am I missing something (other than the aforementioned powertop)?

By the way, this is a desktop PC, so all this discussion on my end may be moot (unless I want to save a few pennies on my electric bill). :-)

Power consumption

Posted Apr 26, 2010 21:47 UTC (Mon) by nix (subscriber, #2304) [Link] (2 responses)

Perhaps C-states are disabled in your BIOS. (Personally, I've disabled them on my suspended-when-not-in-use desktop simply because when C states are disabled, if the TSC is otherwise stable it can be used as a time source rather than the expensive HPET. On always-on servers and power-important laptops and netbooks, a bit of timekeepoing expense is worth the power saving, so it's best to turn C states on.)

Power consumption

Posted Apr 27, 2010 0:45 UTC (Tue) by pr1268 (guest, #24648) [Link] (1 responses)

I've got S3 enabled in BIOS (I actually rebooted just to look), but I'm curious whether I've got all the proper kernel options set and modules compiled/installed. Sounds like a research project... :-)

Thanks for the replies.

S3 is different

Posted Apr 29, 2010 22:29 UTC (Thu) by pflugstad (subscriber, #224) [Link]

IIRC, S3 is suspend-system-to-RAM, as opposed to the C states, which are just CPU states.

Power consumption

Posted Apr 27, 2010 0:55 UTC (Tue) by arjan (subscriber, #36785) [Link]

some desktop pc's support C states... but many, especially slightly older ones (1 - 2 years old), do not.

Power consumption

Posted Apr 27, 2010 0:55 UTC (Tue) by xtifr (guest, #143) [Link]

On my system, I have /sys/devices/system/cpu/cpuidle (not in the cpu0 subdir).