On Wed, Dec 30, 2020 at 1:24 AM Mark Pearson <markpearson@xxxxxxxxxx> wrote: > > On modern systems the platform performance, temperature, fan and other > hardware related characteristics are often dynamically configurable. The > profile is often automatically adjusted to the load by some > automatic-mechanism (which may very well live outside the kernel). > > These auto platform-adjustment mechanisms often can be configured with > one of several 'platform-profiles', with either a bias towards low-power > consumption or towards performance (and higher power consumption and > thermals). > > Introduce a new platform_profile sysfs API which offers a generic API for > selecting the performance-profile of these automatic-mechanisms. > > Co-developed-by: Mark Pearson <markpearson@xxxxxxxxxx> > Signed-off-by: Mark Pearson <markpearson@xxxxxxxxxx> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> Applied, thanks! > --- > Changes in v2: > - updated to rst format > Changes in v3, v4, v5 > - version bump along with rest of patch series > Changes in v6: > - Split sysfs-platform_profile.rs into ABI text and then admin guide in > userspace-api section. Hope this is correct - I'm guessing a bit. > Changes in v7: > - Correct available_choices to platform_profile_choices > - Improve phrasing as recommended by review > Changes in v8: > - Removed unnecessary empty lines at end of file > > .../ABI/testing/sysfs-platform_profile | 24 +++++++++++ > Documentation/userspace-api/index.rst | 1 + > .../userspace-api/sysfs-platform_profile.rst | 42 +++++++++++++++++++ > 3 files changed, 67 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-platform_profile > create mode 100644 Documentation/userspace-api/sysfs-platform_profile.rst > > diff --git a/Documentation/ABI/testing/sysfs-platform_profile b/Documentation/ABI/testing/sysfs-platform_profile > new file mode 100644 > index 000000000000..9d6b89b66cca > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-platform_profile > @@ -0,0 +1,24 @@ > +What: /sys/firmware/acpi/platform_profile_choices > +Date: October 2020 > +Contact: Hans de Goede <hdegoede@xxxxxxxxxx> > +Description: This file contains a space-separated list of profiles supported for this device. > + > + Drivers must use the following standard profile-names: > + > + ============ ============================================ > + low-power Low power consumption > + cool Cooler operation > + quiet Quieter operation > + balanced Balance between low power consumption and performance > + performance High performance operation > + ============ ============================================ > + > + Userspace may expect drivers to offer more than one of these > + standard profile names. > + > +What: /sys/firmware/acpi/platform_profile > +Date: October 2020 > +Contact: Hans de Goede <hdegoede@xxxxxxxxxx> > +Description: Reading this file gives the current selected profile for this > + device. Writing this file with one of the strings from > + platform_profile_choices changes the profile to the new value. > diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst > index acd2cc2a538d..d29b020e5622 100644 > --- a/Documentation/userspace-api/index.rst > +++ b/Documentation/userspace-api/index.rst > @@ -24,6 +24,7 @@ place where this information is gathered. > ioctl/index > iommu > media/index > + sysfs-platform_profile > > .. only:: subproject and html > > diff --git a/Documentation/userspace-api/sysfs-platform_profile.rst b/Documentation/userspace-api/sysfs-platform_profile.rst > new file mode 100644 > index 000000000000..c33a71263d9e > --- /dev/null > +++ b/Documentation/userspace-api/sysfs-platform_profile.rst > @@ -0,0 +1,42 @@ > +===================================================================== > +Platform Profile Selection (e.g. /sys/firmware/acpi/platform_profile) > +===================================================================== > + > +On modern systems the platform performance, temperature, fan and other > +hardware related characteristics are often dynamically configurable. The > +platform configuration is often automatically adjusted to the current > +conditions by some automatic mechanism (which may very well live outside > +the kernel). > + > +These auto platform adjustment mechanisms often can be configured with > +one of several platform profiles, with either a bias towards low power > +operation or towards performance. > + > +The purpose of the platform_profile attribute is to offer a generic sysfs > +API for selecting the platform profile of these automatic mechanisms. > + > +Note that this API is only for selecting the platform 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 on their own cannot represent the multiple variables that a > +profile will adjust (power consumption, heat generation, etc) this API > +uses strings to describe the various profiles. To make sure that userspace > +gets a consistent experience the sysfs-platform_profile ABI document defines > +a fixed set of profile names. Drivers *must* map their internal profile > +representation onto this fixed set. > + > +If 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. Explain why the existing profile names canot be used. > + 2. Add the new profile name, along with a clear description of the > + expected behaviour, to the sysfs-platform_profile ABI documentation. > -- > 2.28.0 >
