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- 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.
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