Messages in this thread | | | Date | Tue, 03 Sep 2013 15:32:56 +0200 | From | Daniel Lezcano <> | Subject | Re: [Query-CPUIdle]: Not much activity in C0 state |
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On 08/27/2013 12:23 PM, Viresh Kumar wrote: > Hi Guys, > > I was trying to run following on my thinkpad: > > watch -n1 cat /sys/devices/system/cpu/cpu*/cpuidle/state*/usage > > I can see lots of activities on State 1-4, but not much on state 0.. > I thought we should enter this state as soon as we come out to > non-idle state.. And so this count must be changing quite rapidly. > > Is this a bug?
Hi Viresh,
the menu governor tries always to stick to C1 (state1) as default state, look at the menu_select function. The state0 (not C0 but 'poll') will happen when the next timer event is less than 5us, this occurs rarely. You can easily spot it by doing while $(true); usleep 2; done
The poll state is x86 specific where the cpu detects the 'rep nop' instructions to do some power saving.
Hope that helps
-- Daniel
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