netdev - Re: [PATCH net-next 00/13] resource management using devlink reload

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Message-ID: <d136e9e4-8962-a399-a1e6-dde4ad28fbed@intel.com>
Date:   Sun, 20 Nov 2022 16:24:18 -0600
From:   "Samudrala, Sridhar" <sridhar.samudrala@...el.com>
To:     Leon Romanovsky <leon@...nel.org>,
        "Saleem, Shiraz" <shiraz.saleem@...el.com>
CC:     Jakub Kicinski <kuba@...nel.org>,
        Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "jiri@...dia.com" <jiri@...dia.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "Lobakin, Alexandr" <alexandr.lobakin@...el.com>,
        "Drewek, Wojciech" <wojciech.drewek@...el.com>,
        "Czapnik, Lukasz" <lukasz.czapnik@...el.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Ismail, Mustafa" <mustafa.ismail@...el.com>,
        "Kitszel, Przemyslaw" <przemyslaw.kitszel@...el.com>,
        "Raczynski, Piotr" <piotr.raczynski@...el.com>,
        "Keller, Jacob E" <jacob.e.keller@...el.com>,
        "Ertman, David M" <david.m.ertman@...el.com>,
        "Kaliszczuk, Leszek" <leszek.kaliszczuk@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH net-next 00/13] resource management using devlink reload

On 11/18/2022 11:31 AM, Leon Romanovsky wrote:
> On Fri, Nov 18, 2022 at 02:23:50PM +0000, Saleem, Shiraz wrote:
>>> Subject: Re: [PATCH net-next 00/13] resource management using devlink reload
>>>
>>> On Thu, Nov 17, 2022 at 07:36:18PM -0800, Jakub Kicinski wrote:
>>>> On Thu, 17 Nov 2022 19:38:48 +0200 Leon Romanovsky wrote:
>>>>> I don't think that management of PCI specific parameters in devlink
>>>>> is right idea. PCI has his own subsystem with rules and assumptions,
>>>>> netdev shouldn't mangle them.
>>>> Not netdev, devlink, which covers netdev, RDMA and others.
>>> devlink is located in net/*, it is netdev.
>>> Regarding RDMA, it is not fully accurate. We use devlink to convey information to
>>> FW through pci device located in netdev. Some of such parameters are RDMA
>>> related. However, we don't configure RDMA properties through devlink, there is a
>>> special tool for that (rdmatool).
>> rdmatool though is usable only once the rdma driver probe() completes and the ib_device is registered.
>> And cannot be used for any configurations at driver init time.
> Like I said, we use devlink to configure FW and "core" device to which
> ib_device is connected. We don't configure RDMA specific properties, but
> only device specific ones.

I don't think this patch series is configuring any PCI specific parameters OR per-PCI device parameters.
The FW splits the device level MSI-X vectors across its PFs(1 per port).
Each PF manages its own MSI-X vectors and distributes them across the different functions associated with that PF.
So far the PF driver has been doing this with a hard-coded policy implemented within the driver.

We are exposing that policy via devlink and allowing a host admin to split the MSI-X vectors that are
assigned to a PF by the FW across its different functions (PF, all its VFs, all its SFs and RDMA) based
on the use cases/workload running on the host.