Re: [PATCH v5 00/10] PM: EM: Add netlink support for the energy model

[Lukasz Luba <lukasz.luba@arm.com>]

On 10/14/25 01:10, Changwoo Min wrote:
> Addressed all the comments from Lukasz and rebased the code to the head
> of the linus tree.
> 
> There is a need to access the energy model from the userspace. One such
> example is the sched_ext schedulers [1]. The userspace part of the
> sched_ext schedules could feed the (post-processed) energy-model
> information to the BPF part of the scheduler.
> 
> Currently, debugfs is the only way to read the energy model from userspace;
> however, it lacks proper notification mechanisms when a performance domain
> and its associated energy model change.
> 
> This patch set introduces a generic netlink for the energy model, as
> discussed in [2]. It allows a userspace program to read the performance
> domain and its energy model. It notifies the userspace program when a
> performance domain is created or deleted or its energy model is updated
> through a multicast interface.
> 
> Specifically, it supports two commands:
>    - EM_CMD_GET_PDS: Get the list of information for all performance
>      domains.
>    - EM_CMD_GET_PD_TABLE: Get the energy model table of a performance
>      domain.
> 
> Also, it supports three notification events:
>    - EM_CMD_PD_CREATED: When a performance domain is created.
>    - EM_CMD_PD_DELETED: When a performance domain is deleted.
>    - EM_CMD_PD_UPDATED: When the energy model table of a performance domain
>      is updated.
> 
> This can be tested using the tool, tools/net/ynl/pyynl/cli.py, for example,
> with the following commands:
> 
>    $> tools/net/ynl/pyynl/cli.py \
>       --spec Documentation/netlink/specs/em.yaml \
>       --do get-pds
>    $> tools/net/ynl/pyynl/cli.py \
>       --spec Documentation/netlink/specs/em.yaml \
>       --do get-pd-table --json '{"pd-id": 0}'
>    $> tools/net/ynl/pyynl/cli.py \
>       --spec Documentation/netlink/specs/em.yaml \
>       --subscribe event  --sleep 10
> 
> [1] https://lwn.net/Articles/922405/
> [2] https://lore.kernel.org/lkml/a82423bc-8c38-4d57-93da-c4f20011cc92@arm.com/
> [3] https://lore.kernel.org/lkml/202506140306.tuIoz8rN-lkp@intel.com/#t

Thank you Changwoo, it looks good.

The patches can go now into some PM testing branches so we can check the
integration/testing in wider configurations.

Regards,
Lukasz