linux-kernel - Re: Intel_pstate: One Core always 100% C0 state and never scale down

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Message-ID: <51D65D4A.1080706@gmail.com>
Date:	Fri, 05 Jul 2013 13:44:42 +0800
From:	Light <sgsdxzy@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: Intel_pstate: One Core always 100% C0 state and never scale down

On 07/04/2013 11:43 AM, Light wrote:
> I am using a laptop with Intel Ivy bridge core i7 3610QM. I updated my 
> kernel to 3.10 and started to use intel_pstate as scaling driver:
> #cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
> intel_pstate
>
> However I find that one of my four cores is always in C0 state even 
> when there is no activities. I monitored it using i7z:
> Core [core-id]  :Actual Freq (Mult.)      C0%   Halt(C1)%  C3 % C6 %   
> C7 %  Temp
>         Core 1 [0]:       3288.24 (32.97x)      99.7       0 0       
> 0       0    83
>         Core 2 [1]:       3138.62 (31.47x)         1       0 0       
> 0    99.7    74
>         Core 3 [2]:       3175.46 (31.84x)         1    0.891 0       
> 0      99    76
>         Core 4 [3]:       3177.34 (31.86x)         1    0.21 0       
> 0    99.3    71
>
> Also cpu frequencies never scale down, resulting in very high temp.
> #cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> powersave
>
> It does say powersave, and my cpu is capable of 1.20Ghz to 3.30Ghz
>
> I don't know if I misconfigured or misunderstood something. Can 
> someone tell me why?
> Thanks!
Switching to dynticks Idle fixed the problem. But I am still wondering 
if it were a bug with full dynticks...
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