netdev - Re: [PATCH/RFC net-next 1/2] devlink: expose port function commands to assign VFs to multiple netdevs

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Message-ID: <Y+OXcvsylX8AzNg8@corigine.com>
Date:   Wed, 8 Feb 2023 13:37:06 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        Gal Pressman <gal@...dia.com>,
        Saeed Mahameed <saeed@...nel.org>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        Edward Cree <ecree.xilinx@...il.com>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Andrew Lunn <andrew@...n.ch>, Fei Qin <fei.qin@...igine.com>,
        netdev@...r.kernel.org, oss-drivers@...igine.com
Subject: Re: [PATCH/RFC net-next 1/2] devlink: expose port function commands
 to assign VFs to multiple netdevs

On Wed, Feb 08, 2023 at 01:34:19PM +0100, Jiri Pirko wrote:
> Wed, Feb 08, 2023 at 01:07:54PM CET, simon.horman@...igine.com wrote:
> >On Wed, Feb 08, 2023 at 12:40:45PM +0100, Jiri Pirko wrote:
> >> Mon, Feb 06, 2023 at 04:36:02PM CET, simon.horman@...igine.com wrote:
> >> >From: Fei Qin <fei.qin@...igine.com>
> >> >
> >> >Multiple physical ports of the same NIC may share the single
> >> >PCI address. In some cases, assigning VFs to different physical
> >> >ports can be demanded, especially under high-traffic scenario.
> >> >Load balancing can be realized in virtualised use¬cases through
> >> >distributing packets between different physical ports with LAGs
> >> >of VFs which are assigned to those physical ports.
> >> >
> >> >This patch adds new attribute "vf_count" to 'devlink port function'
> >> >API which only can be shown and configured under devlink ports
> >> >with flavor "DEVLINK_PORT_FLAVOUR_PHYSICAL".
> >> 
> >> I have to be missing something. That is the meaning of "assigning VF"
> >> to a physical port? Why there should be any relationship between
> >> physical port and VF other than configured forwarding (using TC for
> >> example)?
> >> 
> >> This seems very wrong. Preliminary NAK.
> >
> >Of course if TC is involved, then we have flexibility.
> >
> >What we are talking about here is primarily legacy mode.
> 
> I don't see any reason to add knobs for purpose of supporting the legacy
> mode, sorry.
> 
> If you need this functionality, use TC.

I understand your point, even if I don't agree in this case.

> >And the behaviour described would, when enabled allow NFP based NICs
> >to behave more like most other multi-port NICs.
> >
> >That is, we can envisage a VEB with some VFs and one physical port.
> >And anther with other VFs and another physical port.
> >
> >This is as opposed to a single VEB with all VFs, as is currently
> >the case on NFP based NICs (but not most other multi-port NICs).
> >