Re: [PATCH net-next v8 07/13] net: pse-pd: Add support for budget evaluation strategies

[Oleksij Rempel]

On Wed, Apr 16, 2025 at 03:44:22PM +0200, Kory Maincent wrote:
> From: Kory Maincent (Dent Project) <kory.maincent@xxxxxxxxxxx>
> 
> This patch introduces the ability to configure the PSE PI budget evaluation
> strategies. Budget evaluation strategies is utilized by PSE controllers to
> determine which ports to turn off first in scenarios such as power budget
> exceedance.
> 
> The pis_prio_max value is used to define the maximum priority level
> supported by the controller. Both the current priority and the maximum
> priority are exposed to the user through the pse_ethtool_get_status call.
> 
> This patch add support for two mode of budget evaluation strategies.
> 1. Static Method:
> 
>    This method involves distributing power based on PD classification.
>    It’s straightforward and stable, the PSE core keeping track of the
>    budget and subtracting the power requested by each PD’s class.
> 
>    Advantages: Every PD gets its promised power at any time, which
>    guarantees reliability.
> 
>    Disadvantages: PD classification steps are large, meaning devices
>    request much more power than they actually need. As a result, the power
>    supply may only operate at, say, 50% capacity, which is inefficient and
>    wastes money.
> 
>    Priority max value is matching the number of PSE PIs within the PSE.
> 
> 2. Dynamic Method:
> 
>    To address the inefficiencies of the static method, vendors like
>    Microchip have introduced dynamic power budgeting, as seen in the
>    PD692x0 firmware. This method monitors the current consumption per port
>    and subtracts it from the available power budget. When the budget is
>    exceeded, lower-priority ports are shut down.
> 
>    Advantages: This method optimizes resource utilization, saving costs.
> 
>    Disadvantages: Low-priority devices may experience instability.
> 
>    Priority max value is set by the PSE controller driver.
> 
> For now, budget evaluation methods are not configurable and cannot be
> mixed. They are hardcoded in the PSE driver itself, as no current PSE
> controller supports both methods.
> 
> Signed-off-by: Kory Maincent (Dent Project) <kory.maincent@xxxxxxxxxxx>

Reviewed-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>

Thank you!

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