1===================================================================== 2Platform Profile Selection (e.g. /sys/firmware/acpi/platform_profile) 3===================================================================== 4 5On modern systems the platform performance, temperature, fan and other 6hardware related characteristics are often dynamically configurable. The 7platform configuration is often automatically adjusted to the current 8conditions by some automatic mechanism (which may very well live outside 9the kernel). 10 11These auto platform adjustment mechanisms often can be configured with 12one of several platform profiles, with either a bias towards low power 13operation or towards performance. 14 15The purpose of the platform_profile attribute is to offer a generic sysfs 16API for selecting the platform profile of these automatic mechanisms. 17 18Note that this API is only for selecting the platform profile, it is 19NOT a goal of this API to allow monitoring the resulting performance 20characteristics. Monitoring performance is best done with device/vendor 21specific tools such as e.g. turbostat. 22 23Specifically when selecting a high performance profile the actual achieved 24performance may be limited by various factors such as: the heat generated 25by other components, room temperature, free air flow at the bottom of a 26laptop, etc. It is explicitly NOT a goal of this API to let userspace know 27about any sub-optimal conditions which are impeding reaching the requested 28performance level. 29 30Since numbers on their own cannot represent the multiple variables that a 31profile will adjust (power consumption, heat generation, etc) this API 32uses strings to describe the various profiles. To make sure that userspace 33gets a consistent experience the sysfs-platform_profile ABI document defines 34a fixed set of profile names. Drivers *must* map their internal profile 35representation onto this fixed set. 36 37If there is no good match when mapping then a new profile name may be 38added. Drivers which wish to introduce new profile names must: 39 40 1. Explain why the existing profile names canot 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. 43