linux-kernel - Re: [v3.10-rc] intel

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Date:	Tue, 28 May 2013 08:52:46 -0700
From:	Dirk Brandewie <dirk.brandewie@...il.com>
To:	Jörg Otte <jrg.otte@...il.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	rafael.j.wysocki@...el.com
Subject: Re: [v3.10-rc] intel_pstate question

Hi Jörg,

On 05/28/2013 08:02 AM, Jörg Otte wrote:
> Hi,
>
> the sysfs-interface of intel_pstate is different to that of the acpi driver:
> - intel_pstate shows current cpu-frequency in "cpuinfo_cur_freq" whereas
>    the acpi counterpart uses "scaling_cur_freq".
> - moreover cpuinfo_cur_freq is readable by root only, whereas
>    scaling_cur_freq is world readable.
>
>    A monitoring tool must take care of theese differences.
>    Is this intentional?
>

This is a side effect of the interface that intel_pstate presents to the cpufreq
core.

cpuinfo_cur_freq reports the value returned from the scaling driver.

scaling_cur_freq reports the current frequency in the governors policy structure.

intel_pstate has an internal governor so the core does not try to interpret
the policy structure.

I don't know why cpuinfo_cur_info is read-only root maybe Rafael knows the history.


> Thanks, Jörg
>
> Please CC me in answeres, I'm not subscribed.
>

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