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From: Jason Wang <jasowang@redhat.com>
To: "Samudrala, Sridhar" <sridhar.samudrala@intel.com>,
	Alexander Duyck <alexander.duyck@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>
Cc: David Ahern <dsahern@gmail.com>, Jason Gunthorpe <jgg@nvidia.com>,
	Parav Pandit <parav@nvidia.com>,
	Saeed Mahameed <saeed@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Jiri Pirko <jiri@nvidia.com>,
	"dledford@redhat.com" <dledford@redhat.com>,
	Leon Romanovsky <leonro@nvidia.com>,
	"davem@davemloft.net" <davem@davemloft.net>
Subject: Re: [PATCH net-next 00/13] Add mlx5 subfunction support
Date: Tue, 24 Nov 2020 15:05:15 +0800	[thread overview]
Message-ID: <fe0a31e2-6384-f14f-87c9-dcf0f7f9fdcb@redhat.com> (raw)
In-Reply-To: <1e7773b1-0954-257f-7355-c17b15ab6b8b@redhat.com>


On 2020/11/24 下午3:01, Jason Wang wrote:
>
> On 2020/11/21 上午3:04, Samudrala, Sridhar wrote:
>>
>>
>> On 11/20/2020 9:58 AM, Alexander Duyck wrote:
>>> On Thu, Nov 19, 2020 at 5:29 PM Jakub Kicinski <kuba@kernel.org> wrote:
>>>>
>>>> On Wed, 18 Nov 2020 21:35:29 -0700 David Ahern wrote:
>>>>> On 11/18/20 7:14 PM, Jakub Kicinski wrote:
>>>>>> On Tue, 17 Nov 2020 14:49:54 -0400 Jason Gunthorpe wrote:
>>>>>>> On Tue, Nov 17, 2020 at 09:11:20AM -0800, Jakub Kicinski wrote:
>>>>>>>
>>>>>>>>> Just to refresh all our memory, we discussed and settled on 
>>>>>>>>> the flow
>>>>>>>>> in [2]; RFC [1] followed this discussion.
>>>>>>>>>
>>>>>>>>> vdpa tool of [3] can add one or more vdpa device(s) on top of 
>>>>>>>>> already
>>>>>>>>> spawned PF, VF, SF device.
>>>>>>>>
>>>>>>>> Nack for the networking part of that. It'd basically be VMDq.
>>>>>>>
>>>>>>> What are you NAK'ing?
>>>>>>
>>>>>> Spawning multiple netdevs from one device by slicing up its queues.
>>>>>
>>>>> Why do you object to that? Slicing up h/w resources for virtual what
>>>>> ever has been common practice for a long time.
>>>>
>>>> My memory of the VMDq debate is hazy, let me rope in Alex into this.
>>>> I believe the argument was that we should offload software constructs,
>>>> not create HW-specific APIs which depend on HW availability and
>>>> implementation. So the path we took was offloading macvlan.
>>>
>>> I think it somewhat depends on the type of interface we are talking
>>> about. What we were wanting to avoid was drivers spawning their own
>>> unique VMDq netdevs and each having a different way of doing it. The
>>> approach Intel went with was to use a MACVLAN offload to approach it.
>>> Although I would imagine many would argue the approach is somewhat
>>> dated and limiting since you cannot do many offloads on a MACVLAN
>>> interface.
>>
>> Yes. We talked about this at netdev 0x14 and the limitations of 
>> macvlan based offloads.
>> https://netdevconf.info/0x14/session.html?talk-hardware-acceleration-of-container-networking-interfaces 
>>
>>
>> Subfunction seems to be a good model to expose VMDq VSI or SIOV ADI 
>> as a netdev for kernel containers. AF_XDP ZC in a container is one of 
>> the usecase this would address. Today we have to pass the entire 
>> PF/VF to a container to do AF_XDP.
>>
>> Looks like the current model is to create a subfunction of a specific 
>> type on auxiliary bus, do some configuration to assign resources and 
>> then activate the subfunction.
>>
>>>
>>> With the VDPA case I believe there is a set of predefined virtio
>>> devices that are being emulated and presented so it isn't as if they
>>> are creating a totally new interface for this.
>
>
> vDPA doesn't have any limitation of how the devices is created or 
> implemented. It could be predefined or created dynamically. vDPA 
> leaves all of those to the parent device with the help of a unified 
> management API[1]. E.g It could be a PCI device (PF or VF), 
> sub-function or  software emulated devices.


Miss the link, https://www.spinics.net/lists/netdev/msg699374.html.

Thanks


>
>
>>>
>>> What I would be interested in seeing is if there are any other vendors
>>> that have reviewed this and sign off on this approach.
>
>
> For "this approach" do you mean vDPA subfucntion? My understanding is 
> that it's totally vendor specific, vDPA subsystem don't want to be 
> limited by a specific type of device.
>
>
>>> What we don't
>>> want to see is Nivida/Mellanox do this one way, then Broadcom or Intel
>>> come along later and have yet another way of doing this. We need an
>>> interface and feature set that will work for everyone in terms of how
>>> this will look going forward.
>
> For feature set,  it would be hard to force (we can have a 
> recommendation set of features) vendors to implement a common set of 
> features consider they can be negotiated. So the management interface 
> is expected to implement features like cpu clusters in order to make 
> sure the migration compatibility, or qemu can assist for the missing 
> feature with performance lose.
>
> Thanks
>
>


  reply	other threads:[~2020-11-24  7:05 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 19:24 Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 01/13] devlink: Prepare code to fill multiple port function attributes Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 02/13] devlink: Introduce PCI SF port flavour and port attribute Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 03/13] devlink: Support add and delete devlink port Parav Pandit
2020-11-18 16:21   ` David Ahern
2020-11-18 17:02     ` Parav Pandit
2020-11-18 18:03       ` David Ahern
2020-11-18 18:38         ` Jason Gunthorpe
2020-11-18 19:36           ` David Ahern
2020-11-18 20:42             ` Jason Gunthorpe
2020-11-18 19:22         ` Parav Pandit
2020-11-19  0:41           ` Jacob Keller
2020-11-19  1:17             ` David Ahern
2020-11-19  1:56               ` Samudrala, Sridhar
2020-11-19  0:52       ` Jacob Keller
2020-11-12 19:24 ` [PATCH net-next 04/13] devlink: Support get and set state of port function Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 05/13] devlink: Avoid global devlink mutex, use per instance reload lock Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 06/13] devlink: Introduce devlink refcount to reduce scope of global devlink_mutex Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 07/13] net/mlx5: SF, Add auxiliary device support Parav Pandit
2020-12-07  2:48   ` David Ahern
2020-12-07  4:53     ` Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 08/13] net/mlx5: SF, Add auxiliary device driver Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 09/13] net/mlx5: E-switch, Prepare eswitch to handle SF vport Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 10/13] net/mlx5: E-switch, Add eswitch helpers for " Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 11/13] net/mlx5: SF, Add SF configuration hardware commands Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 12/13] net/mlx5: SF, Add port add delete functionality Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 13/13] net/mlx5: SF, Port function state change support Parav Pandit
2020-11-16 22:52 ` [PATCH net-next 00/13] Add mlx5 subfunction support Jakub Kicinski
2020-11-17  0:06   ` Saeed Mahameed
2020-11-17  1:58     ` Jakub Kicinski
2020-11-17  4:08       ` Parav Pandit
2020-11-17 17:11         ` Jakub Kicinski
2020-11-17 18:49           ` Jason Gunthorpe
2020-11-19  2:14             ` Jakub Kicinski
2020-11-19  4:35               ` David Ahern
2020-11-19  5:57                 ` Saeed Mahameed
2020-11-20  1:31                   ` Jakub Kicinski
2020-11-25  5:33                   ` David Ahern
2020-11-25  6:00                     ` Parav Pandit
2020-11-25 14:37                       ` David Ahern
2020-11-20  1:29                 ` Jakub Kicinski
2020-11-20 17:58                   ` Alexander Duyck
2020-11-20 19:04                     ` Samudrala, Sridhar
2020-11-23 21:51                       ` Saeed Mahameed
2020-11-24  7:01                       ` Jason Wang
2020-11-24  7:05                         ` Jason Wang [this message]
2020-11-19  6:12               ` Saeed Mahameed
2020-11-19  8:25                 ` Parav Pandit
2020-11-20  1:35                 ` Jakub Kicinski
2020-11-20  3:34                   ` Parav Pandit
2020-11-17 18:50           ` Parav Pandit
2020-11-19  2:23             ` Jakub Kicinski
2020-11-19  6:22               ` Saeed Mahameed
2020-11-19 14:00                 ` Jason Gunthorpe
2020-11-20  3:35                   ` Jakub Kicinski
2020-11-20  3:50                     ` Parav Pandit
2020-11-20 16:16                     ` Jason Gunthorpe

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