<Note - switched my email address to my more open source non-outlook
based address>
On 2020-10-16 10:32 a.m., Mark Pearson wrote:
>
>
> ------------------------------------------------------------------------
> *From:* Elia Devito <[email protected]>
> *Sent:* October 16, 2020 10:26
> *To:* Rafael J. Wysocki <[email protected]>; Hans de Goede
> <[email protected]>
> *Cc:* Daniel Lezcano <[email protected]>; Srinivas Pandruvada
> <[email protected]>; Lukasz Luba
> <[email protected]>; Linux Kernel Mailing List
> <[email protected]>; Linux PM <[email protected]>;
> Zhang, Rui <[email protected]>; Bastien Nocera <[email protected]>;
> Mark Pearson <[email protected]>; Limonciello, Mario
> <[email protected]>; Darren Hart <[email protected]>; Andy
> Shevchenko <[email protected]>; Mark Gross <[email protected]>;
> Benjamin Berg <[email protected]>; [email protected]
> <[email protected]>; [email protected]
> <[email protected]>
> *Subject:* [External] Re: [RFC] Documentation: Add documentation for new
> performance_profile sysfs class (Also Re: [PATCH 0/4] powercap/dtpm: Add
> the DTPM framework)
> Hi,
>
> In data venerdì 16 ottobre 2020 13:10:54 CEST, Hans de Goede ha scritto:
>> <note folding the 2 threads we are having on this into one, adding every one
>> from both threads to the Cc>
>>
>> Hi,
>>
>> On 10/14/20 5:42 PM, Rafael J. Wysocki wrote:
>> > On Wed, Oct 14, 2020 at 4:06 PM Hans de Goede <[email protected]> wrote:
>> >> On 10/14/20 3:33 PM, Rafael J. Wysocki wrote:
>> <snip>
>>
>> >>> First, a common place to register a DPTF system profile seems to be
>> >>> needed and, as I said above, I wouldn't expect more than one such
>> >>> thing to be present in the system at any given time, so it may be
>> >>> registered along with the list of supported profiles and user space
>> >>> will have to understand what they mean.
>> >>
>> >> Mostly Ack, I would still like to have an enum for DPTF system
>> >> profiles in the kernel and have a single piece of code map that
>> >> enum to profile names. This enum can then be extended as
>> >> necessary, but I want to avoid having one driver use
>> >> "Performance" and the other "performance" or one using
>> >> "performance-balanced" and the other "balanced-performance", etc.
>> >>
>> >> With the goal being that new drivers use existing values from
>> >> the enum as much as possible, but we extend it where necessary.
>> >
>> > IOW, just a table of known profile names with specific indices assigned to
>> > them.
>> Yes.
>>
>> > This sounds reasonable.
>> >
>> >>> Second, irrespective of the above, it may be useful to have a
>> >>> consistent way to pass performance-vs-power preference information
>> >>> from user space to different parts of the kernel so as to allow them
>> >>> to adjust their operation and this could be done with a system-wide
>> >>> power profile attribute IMO.
>> >>
>> >> I agree, which is why I tried to tackle both things in one go,
>> >> but as you said doing both in 1 API is probably not the best idea.
>> >> So I believe we should park this second issue for now and revisit it
>> >> when we find a need for it.
>> >
>> > Agreed.
>> >
>> >> Do you have any specific userspace API in mind for the
>> >> DPTF system profile selection?
>> >
>> > Not really.
>>
>> So before /sys/power/profile was mentioned, but that seems more like
>> a thing which should have a set of fixed possible values, iow that is
>> out of scope for this discussion.
>>
>> Since we all seem to agree that this is something which we need
>> specifically for DPTF profiles maybe just add:
>>
>> /sys/power/dptf_current_profile (rw)
>> /sys/power/dptf_available_profiles (ro)
>>
>> (which will only be visible if a dptf-profile handler
>> has been registered) ?
>>
>> Or more generic and thus better (in case other platforms
>> later need something similar) I think, mirror the:
>>
>> /sys/bus/cpu/devices/cpu#/cpufreq/energy_performance_* bits
>> for a system-wide energy-performance setting, so we get:
>>
>> /sys/power/energy_performance_preference
>> /sys/power/energy_performance_available_preferences
>>
>> (again only visible when applicable) ?
>>
>> I personally like the second option best.
>>
>> Regards,
>>
>> Hans
>
> between the two, the second seems to me more appropriate.
> Considering that the various profiles interact with thermal behaviors
> what do
> you think of something like:
>
> /sys/power/thermal_profile_available_profiles
> /sys/power/thermal_profile_profile
>
> Regards,
> Elia
>
I'm good with either but I do find 'profile_profile' slightly awkward to
say out loud (even though it's logically correct :))
How about just:
/sys/power/platform_profile
/sys/power/platform_profile_available
As it covers the platform as a whole - fans, temperature, power, and
anything else that ends up getting thrown in?
Mark