Re: [PATCH net-next v5 06/12] net: pse-pd: Add support for budget evaluation strategies

Oleksij Rempel
2025-02-26T06:00:35Z

On Tue, Feb 25, 2025 at 05:47:52PM -0800, Jakub Kicinski wrote:
> On Tue, 25 Feb 2025 10:25:58 +0100 Kory Maincent wrote:
> > On Mon, 24 Feb 2025 13:45:22 -0800
> > Jakub Kicinski <kuba@kernel.org> wrote:
> >
> > > > No they can't for now. Even different PSE power domains within the same PSE
> > > > controller. I will make it explicit.
> > >
> > > Sounds like the property is placed at the wrong level of the hierarchy,
> > > then.
> >
> > When a PSE controller appears to be able to support mixed budget strategy and
> > could switch between them it will be better to have it set at the PSE power
> > domain level. As the budget is per PSE power domain, its strategy should also
> > be per PSE power domain.
> > For now, it is simply not configurable and can't be mixed. It is hard-coded by
> > the PSE driver.
>
> Yes, but uAPI is forever. We will have to live with those domain
> attributes duplicated on each port. Presumably these port attributes
> will never support a SET operation, since the set should be towards
> the domain? The uAPI does not inspire confidence. If we need more
> drivers to define a common API maybe a local sysfs API in the driver
> will do?

I tend to disagree here. The evaluation/allocation methods should be
per port.

At this step, we support only "hardware"(firmware)-based methods:
1. Static – Plain hardware classification-based power allocation per
port.
2. Dynamic – Hardware classification with constant measurement for
optimization.

For some devices, the dynamic method may not work reliably enough,
so we will need to switch to a fixed allocation method, which is
currently not implemented but will be set via user space. This
should be configurable per port.

At some point, we will need to introduce LLDP-based allocation from
user space. This will be managed by a daemon.

For testing, here’s an example of how LLDP-based power negotiation can
be analyzed:
https://telecomtest.com.au/wp-content/uploads/2016/12/PDA-LLDP-Powered-Device-LLDP-Analyzer.pdf

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