1 ===================================================================== 2 Platform Profile Selection (e.g. /sys/firmware/acpi/platform_profile) 3 ===================================================================== 4 5 On modern systems the platform performance, temperature, fan and other 6 hardware related characteristics are often dynamically configurable. The 7 platform configuration is often automatically adjusted to the current 8 conditions by some automatic mechanism (which may very well live outside 9 the kernel). 10 11 These auto platform adjustment mechanisms often can be configured with 12 one of several platform profiles, with either a bias towards low power 13 operation or towards performance. 14 15 The purpose of the platform_profile attribute is to offer a generic sysfs 16 API for selecting the platform profile of these automatic mechanisms. 17 18 Note that this API is only for selecting the platform profile, it is 19 NOT a goal of this API to allow monitoring the resulting performance 20 characteristics. Monitoring performance is best done with device/vendor 21 specific tools such as e.g. turbostat. 22 23 Specifically when selecting a high performance profile the actual achieved 24 performance may be limited by various factors such as: the heat generated 25 by other components, room temperature, free air flow at the bottom of a 26 laptop, etc. It is explicitly NOT a goal of this API to let userspace know 27 about any sub-optimal conditions which are impeding reaching the requested 28 performance level. 29 30 Since numbers on their own cannot represent the multiple variables that a 31 profile will adjust (power consumption, heat generation, etc) this API 32 uses strings to describe the various profiles. To make sure that userspace 33 gets a consistent experience the sysfs-platform_profile ABI document defines 34 a fixed set of profile names. Drivers *must* map their internal profile 35 representation onto this fixed set. 36 37 If there is no good match when mapping then a new profile name may be 38 added. Drivers which wish to introduce new profile names must: 39 40 1. Explain why the existing profile names cannot be used. 41 2. Add the new profile name, along with a clear description of the 42 expected behaviour, to the sysfs-platform_profile ABI documentation.
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