Re: [PATCH v5 23/23] Documentation: EM: Update with runtime modification design

Dietmar Eggemann
2023-12-12T18:52:08Z

On 29/11/2023 12:08, Lukasz Luba wrote:
> Add a new section 'Design' which covers the information about Energy
> Model. It contains the design decisions, describes models and how they
> reflect the reality. Remove description of the default EM. Change the
> other section IDs. Add documentation bit for the new feature which
> allows to modify the EM in runtime.
>
> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> ---
> Documentation/power/energy-model.rst | 206 +++++++++++++++++++++++++--
> 1 file changed, 196 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst
> index 13225965c9a4..1f8cf36914b1 100644
> --- a/Documentation/power/energy-model.rst
> +++ b/Documentation/power/energy-model.rst
> @@ -72,16 +72,48 @@ required to have the same micro-architecture. CPUs in different performance
> domains can have different micro-architectures.
>
>
> -2. Core APIs
> +2. Design
> +-----------------
> +
> +2.1 Runtime modifiable EM
> +^^^^^^^^^^^^^^^^^^^^^^^^^

The issue I see here is that since now the EM is runtime modifiable and
there is only one EM people might be confused in locking for a
non-runtime modifiable EM. (which matches the design till v4).

So 'runtime modifiability' is now feature of the EM itself.

There is also a figure in this document illustrating the use of
em_get_energy(), em_cpu_get() and em_dev_register_perf_domain().

I wonder if this should be extended to cover all the new interfaces
created for the 'runtime modifiability' feature? …