Hi, seems reasonable to me. Quite simple, but likely good enough as we are sticking to only use well known names.
Just found a small typo. Benjamin On Sat, 2020-10-03 at 15:19 +0200, Hans de Goede wrote: > On modern systems CPU/GPU/... performance is often dynamically configurable > in the form of e.g. variable clock-speeds and TPD. The performance is often > automatically adjusted to the load by some automatic-mechanism (which may > very well live outside the kernel). > > These auto performance-adjustment mechanisms often can be configured with > one of several performance-profiles, with either a bias towards low-power > consumption (and cool and quiet) or towards performance (and higher power > consumption and thermals). > > Introduce a new performance_profile class/sysfs API which offers a generic > API for selecting the performance-profile of these automatic-mechanisms. > > Cc: Mark Pearson <markpear...@lenovo.com> > Cc: Elia Devito <eliadev...@gmail.com> > Cc: Bastien Nocera <had...@hadess.net> > Cc: Benjamin Berg <bb...@redhat.com> > Cc: linux...@vger.kernel.org > Cc: linux-a...@vger.kernel.org > Signed-off-by: Hans de Goede <hdego...@redhat.com> > --- > .../testing/sysfs-class-performance_profile | 104 ++++++++++++++++++ > 1 file changed, 104 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-class-performance_profile > > diff --git a/Documentation/ABI/testing/sysfs-class-performance_profile > b/Documentation/ABI/testing/sysfs-class-performance_profile > new file mode 100644 > index 000000000000..9c67cae39600 > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-class-performance_profile > @@ -0,0 +1,104 @@ > +Performance-profile selection (e.g. > /sys/class/performance_profile/thinkpad_acpi/) > + > +On modern systems CPU/GPU/... performance is often dynamically configurable > +in the form of e.g. variable clock-speeds and TPD. The performance is often > +automatically adjusted to the load by some automatic-mechanism (which may > +very well live outside the kernel). > + > +These auto performance-adjustment mechanisms often can be configured with > +one of several performance-profiles, with either a bias towards low-power > +consumption (and cool and quiet) or towards performance (and higher power > +consumption and thermals). > + > +The purpose of the performance_profile class is to offer a generic sysfs > +API for selecting the performance-profile of these automatic-mechanisms. > + > +Note that this API is only for selecting the performance-profile, it is > +NOT a goal of this API to allow monitoring the resulting performance > +characteristics. Monitoring performance is best done with device/vendor > +specific tools such as e.g. turbostat. > + > +Specifically when selecting a high-performance profile the actual achieved > +performance may be limited by various factors such as: the heat generated by > +other components, room temperature, free air flow at the bottom of a laptop, > +etc. It is explicitly NOT a goal of this API to let userspace know about > +any sub-optimal conditions which are impeding reaching the requested > +performance level. > + > +Since numbers are a rather meaningless way to describe performance-profiles > +this API uses strings to describe the various profiles. To make sure that > +userspace gets a consistent experience when using this API this API document > +defines a fixed set of profile-names. Drivers *must* map their internal > +profile representation/names onto this fixed set. > + > +If for some reason there is no good match when mapping then a new > profile-name > +may be added. Drivers which wish to introduce new profile-names must: > +1. Have very good reasons to do so. > +2. Add the new profile-name to this document, so that future drivers which > also > + have a similar problem can use the same new. Usually new profile-names > will Typo, "new" -> "name" I suppose. > + be added to the "extra profile-names" section of this document. But in > some > + cases the set of standard profile-names may be extended. > + > +What: > /sys/class/performance_profile/<device>/available_profiles > +Date: October 2020 > +Contact: Hans de Goede <hdego...@redhat.com> > +Description: > + Reading this file gives a space separated list of profiles > + supported for this device. > + > + Drivers must use the following standard profile-names whenever > + possible: > + > + low-power: Emphasises low power consumption > + (and also cool and quiet) > + balanced-low-power: Balances between low power consumption > + and performance with a slight bias > + towards low power > + balanced: Balance between low power consumption > + and performance > + balanced-performance: Balances between performance and low > + power consumption with a slight bias > + towards performance > + performance: Emphasises performance (and may lead to > + higher temperatures and fan speeds) > + > + Userspace may expect drivers to offer at least several of these > + standard profile-names! If none of the above are a good match > + for some of the drivers profiles, then drivers may use one of > + these extra profile-names: > + <reserved for future use> > + > +What: /sys/class/performance_profile/<device>/current_profile > +Date: October 2020 > +Contact: Hans de Goede <hdego...@redhat.com> > +Description: > + Reading this file gives the current selected profile for this > + device. Writing this file with one of the strings from > + available_profiles changes the profile to the new value. > + > + Reading this file may also return "custom". This is intended for > + drivers which have and export multiple knobs influencing > + performance. Such drivers may very well still want to offer a > + set of profiles for easy of use and to be able to offer a > + consistent standard API (this API) to userspace for configuring > + their performance. The "custom" value is intended for when a > + user has directly configured the knobs (through e.g. some > + advanced control-panel for a GPU) and the knob values do not > + match any of the presets represented by the > + performance-profiles. In this case writing this file will > + override the modifications and restore the selected presets. > + > +What: /sys/class/performance_profile/<device>/type > +Date: October 2020 > +Contact: Hans de Goede <hdego...@redhat.com> > +Description: > + Performance-profiles may be system-wide, or for a specific > + device (e.g. CPU / GPU). System-wide profiles are typically > + used on devices where where a single cooling solution is > + shared between all components, such as laptops and NUCs. > + > + Reading this file indicates the type of the device for which > + the thermal-profile is being configured. > + > + Valid values: "system" > + Reserved for future use values: "cpu", "gpu"
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