Hey Hans, Mark, On Tue, 2020-10-27 at 12:42 -0400, Mark Pearson wrote: > From: Hans de Goede <hdegoede@xxxxxxxxxx> > > 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 somei > 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 Can you please make sure to quote 'platform-profile' and 'profile-name' this way all through the document? They're not existing words, and quoting them shows that they're attribute names, rather than English. > consumption or towards performance (and higher power consumption and > thermals). s/thermal/temperature/ "A thermal" is something else (it's seasonal underwear for me ;) > 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> > --- > Changes in V1: > - Moved from RFC to proposed patch > - Added cool profile as requested > - removed extra-profiles as no longer relevant > > .../ABI/testing/sysfs-platform_profile | 66 > +++++++++++++++++++ > 1 file changed, 66 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-platform_profile > > diff --git a/Documentation/ABI/testing/sysfs-platform_profile > b/Documentation/ABI/testing/sysfs-platform_profile > new file mode 100644 > index 000000000000..240bd3d7532b > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-platform_profile > @@ -0,0 +1,66 @@ > +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 > +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). > + > +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 are a rather meaningless way to describe platform- > profiles It's not meaningless, but rather ambiguous. For a range of 1 to 5, is 1 high performance, and 5 low power, or vice-versa? > +this API uses strings to describe the various profiles. To make sure > that > +userspace gets a consistent experience when using this API this API you can remove "when using 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. "for some reason" can be removed. > Drivers which wish to introduce new profile-names must: > +1. Have very good reasons to do so. "1. Explain why the existing 'profile-names' cannot be used" > +2. Add the new profile-name to this document, so that future drivers > which also > + have a similar problem can use the same name. "2. Add the new 'profile-name' to the documentation so that other drivers can use it, as well as user-space knowing clearly what behaviour the 'profile-name' corresponds to" > + > +What: /sys/firmware/acpi/platform_profile_choices > +Date: October 2020 > +Contact: Hans de Goede <hdegoede@xxxxxxxxxx> > +Description: > + Reading this file gives a space separated list of > profiles > + supported for this device. "This file contains a space-separated list of profiles..." > + > + Drivers must use the following standard profile- > names: > + > + low-power: Emphasises low power > consumption > + cool: Emphasises cooler operation > + quiet: Emphasises quieter operation > + balanced: Balance between low power > consumption > + and performance > + performance: Emphasises performance (and > may lead to > + higher temperatures and fan > speeds) I'd replace "Emphasises" with either "Focus on" or the US English spelling of "Emphasizes". > + Userspace may expect drivers to offer at least > several of these > + standard profile-names. Replce "at least several" with "more than one". > + > +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 > + available_profiles changes the profile to the new > value. Is there another file which explains whether those sysfs value will contain a trailing linefeed? Cheers
