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