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Power consumptionPower consumptionPosted Apr 26, 2010 18:37 UTC (Mon) by koch (subscriber, #55163)Parent article: The cpuidle subsystem
How did you get the numbers for the power consumption of the different power-states?
Thank you for an excellent article.
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Power consumption Posted Apr 26, 2010 18:42 UTC (Mon) by corbet (editor, #1) [Link] Sorry, I should have mentioned that in the article. Wander into
/sys/devices/system/cpu/cpu0/cpuidle
and you'll find a bunch of files with that information. The time and usage numbers are there too.
Power consumption Posted Apr 26, 2010 20:58 UTC (Mon) by pr1268 (subscriber, #24648) [Link] 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]
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 (subscriber, #24648) [Link] 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 (subscriber, #143) [Link]
On my system, I have /sys/devices/system/cpu/cpuidle (not in the cpu0 subdir).
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