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The recently introduced Energy Model (EM) framework manages power cost
tables of CPUs. These tables are currently only visible from kernel
space. However, in order to debug the behaviour of subsystems that use
the EM (EAS for example), it is often required to know what the power
costs are from userspace.
For this reason, introduce under /sys/kernel/debug/energy_model a set of
directories representing the performance domains of the system. Each
performance domain contains a set of sub-directories representing the
different capacity states (cs) and their attributes, as well as a file
exposing the related CPUs.
The resulting hierarchy is as follows on Arm juno r0 for example:
/sys/kernel/debug/energy_model
├── pd0
│ ├── cpus
│ ├── cs:450000
│ │ ├── cost
│ │ ├── frequency
│ │ └── power
│ ├── cs:575000
│ │ ├── cost
│ │ ├── frequency
│ │ └── power
│ ├── cs:700000
│ │ ├── cost
│ │ ├── frequency
│ │ └── power
│ ├── cs:775000
│ │ ├── cost
│ │ ├── frequency
│ │ └── power
│ └── cs:850000
│ ├── cost
│ ├── frequency
│ └── power
└── pd1
├── cpus
├── cs:1100000
│ ├── cost
│ ├── frequency
│ └── power
├── cs:450000
│ ├── cost
│ ├── frequency
│ └── power
├── cs:625000
│ ├── cost
│ ├── frequency
│ └── power
├── cs:800000
│ ├── cost
│ ├── frequency
│ └── power
└── cs:950000
├── cost
├── frequency
└── power
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.