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?
Thanks, Jörg
Please CC me in answeres, I'm not subscribed.
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.
>
2013/5/28 Dirk Brandewie <[email protected]>:
> 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.
>
Thank you Dirk, for the information!
Just another question: Now that processor 3a is supported, I am giving
pstate driver a try on my notebook. This is the first time I see frequencies
between above 2.5 and up to 3.1 GHz. With cpufreq driver I never saw that
frequencies.
So I think pstate driver uses turbo mode if appropriate (in contrast to
cpufreq). is this correct?
Thanks, Jörg