From: Jiri Pirko <jiri@resnulli.us>
To: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Parav Pandit <parav@mellanox.com>,
alex.williamson@redhat.com, davem@davemloft.net,
kvm@vger.kernel.org, netdev@vger.kernel.org, saeedm@mellanox.com,
kwankhede@nvidia.com, leon@kernel.org, cohuck@redhat.com,
jiri@mellanox.com, linux-rdma@vger.kernel.org,
Or Gerlitz <gerlitz.or@gmail.com>
Subject: Re: [PATCH net-next 00/19] Mellanox, mlx5 sub function support
Date: Fri, 8 Nov 2019 22:39:52 +0100 [thread overview]
Message-ID: <20191108213952.GZ6990@nanopsycho> (raw)
In-Reply-To: <20191108132120.510d8b87@cakuba>
Fri, Nov 08, 2019 at 10:21:20PM CET, jakub.kicinski@netronome.com wrote:
>On Fri, 8 Nov 2019 20:41:18 +0100, Jiri Pirko wrote:
>> Fri, Nov 08, 2019 at 08:06:40PM CET, jakub.kicinski@netronome.com wrote:
>> >On Fri, 8 Nov 2019 13:12:33 +0100, Jiri Pirko wrote:
>> >> Thu, Nov 07, 2019 at 09:32:34PM CET, jakub.kicinski@netronome.com wrote:
>> >> >On Thu, 7 Nov 2019 10:04:48 -0600, Parav Pandit wrote:
>> >> >> Mellanox sub function capability allows users to create several hundreds
>> >> >> of networking and/or rdma devices without depending on PCI SR-IOV support.
>> >> >
>> >> >You call the new port type "sub function" but the devlink port flavour
>> >> >is mdev.
>> >> >
>> >> >As I'm sure you remember you nacked my patches exposing NFP's PCI
>> >> >sub functions which are just regions of the BAR without any mdev
>> >> >capability. Am I in the clear to repost those now? Jiri?
>> >>
>> >> Well question is, if it makes sense to have SFs without having them as
>> >> mdev? I mean, we discussed the modelling thoroughtly and eventually we
>> >> realized that in order to model this correctly, we need SFs on "a bus".
>> >> Originally we were thinking about custom bus, but mdev is already there
>> >> to handle this.
>> >
>> >But the "main/real" port is not a mdev in your case. NFP is like mlx4.
>> >It has one PCI PF for multiple ports.
>>
>> I don't see how relevant the number of PFs-vs-uplink_ports is.
>
>Well. We have a slice per external port, the association between the
>port and the slice becomes irrelevant once switchdev mode is enabled,
>but the queues are assigned statically so it'd be a waste of resources
>to not show all slices as netdevs.
>
>> >> Our SFs are also just regions of the BAR, same thing as you have.
>> >>
>> >> Can't you do the same for nfp SFs?
>> >> Then the "mdev" flavour is enough for all.
>> >
>> >Absolutely not.
>> >
>> >Why not make the main device of mlx5 a mdev, too, if that's acceptable.
>> >There's (a) long precedence for multiple ports on one PCI PF in
>> >networking devices, (b) plenty deployed software
>> >which depend on the main devices hanging off the PCI PF directly.
>> >
>> >The point of mdevs is being able to sign them to VFs or run DPDK on
>> >them (map to user space).
>> >
>> >For normal devices existing sysfs hierarchy were one device has
>> >multiple children of a certain class, without a bus and a separate
>> >driver is perfectly fine. Do you think we should also slice all serial
>> >chips into mdevs if they have multiple lines.
>> >
>> >Exactly as I predicted much confusion about what's being achieved here,
>> >heh :)
>>
>> Please let me understand how your device is different.
>> Originally Parav didn't want to have mlx5 subfunctions as mdev. He
>> wanted to have them tight to the same pci device as the pf. No
>> difference from what you describe you want. However while we thought
>> about how to fit things in, how to handle na phys_port_name, how to see
>> things in sysfs we came up with an idea of a dedicated bus.
>
>The difference is that there is naturally a main device and subslices
>with this new mlx5 code. In mlx4 or nfp all ports are equal and
>statically allocated when FW initializes based on port breakout.
Ah, I see. I was missing the static part in nfp. Now I understand. It is
just an another "pf", but not real pf in the pci terminology, right?
>
>Maybe it's the fact I spent last night at an airport but I'm feeling
>like I'm arguing about this stronger than I actually care :)
>
>> We took it upstream and people suggested to use mdev bus for this.
>>
>> Parav, please correct me if I'm wrong but I don't think where is a plan
>> to push SFs into VM or to userspace as Jakub expects, right?
>
>There's definitely a plan to push them to VFs, I believe that was part
>of the original requirements, otherwise there'd be absolutely no need
>for a bus to begin with.
next prev parent reply other threads:[~2019-11-08 21:39 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 16:04 [PATCH net-next 00/19] Mellanox, mlx5 sub function support Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 02/19] net/mlx5: E-Switch, Add SF vport, vport-rep support Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 03/19] net/mlx5: Introduce SF table framework Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 04/19] net/mlx5: Introduce SF life cycle APIs to allocate/free Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 05/19] net/mlx5: E-Switch, Enable/disable SF's vport during SF life cycle Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 06/19] net/mlx5: Add support for mediated devices in switchdev mode Parav Pandit
2019-11-08 10:32 ` Jiri Pirko
2019-11-08 16:03 ` Parav Pandit
2019-11-08 16:22 ` Jiri Pirko
2019-11-08 16:29 ` Parav Pandit
2019-11-08 18:01 ` Jiri Pirko
2019-11-08 18:04 ` Jiri Pirko
2019-11-08 18:21 ` Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev alias Parav Pandit
2019-11-08 11:04 ` Jiri Pirko
2019-11-08 15:59 ` Parav Pandit
2019-11-08 16:28 ` Jiri Pirko
2019-11-08 11:10 ` Cornelia Huck
2019-11-08 16:03 ` Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 08/19] vfio/mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-11-08 10:49 ` Jiri Pirko
2019-11-08 15:13 ` Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 09/19] vfio/mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-11-08 13:22 ` Jiri Pirko
2019-11-08 18:03 ` Alex Williamson
2019-11-08 18:16 ` Jiri Pirko
2019-11-07 16:08 ` [PATCH net-next 10/19] vfio/mdev: Introduce an API mdev_alias Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 11/19] vfio/mdev: Improvise mdev life cycle and parent removal scheme Parav Pandit
2019-11-08 13:01 ` Cornelia Huck
2019-11-08 16:12 ` Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 12/19] devlink: Introduce mdev port flavour Parav Pandit
2019-11-07 20:38 ` Jakub Kicinski
2019-11-07 21:03 ` Parav Pandit
2019-11-08 1:17 ` Jakub Kicinski
2019-11-08 1:44 ` Parav Pandit
2019-11-08 2:20 ` Jakub Kicinski
2019-11-08 2:31 ` Parav Pandit
2019-11-08 9:46 ` Jiri Pirko
2019-11-08 15:45 ` Parav Pandit
2019-11-08 16:31 ` Jiri Pirko
2019-11-08 16:43 ` Parav Pandit
2019-11-08 18:11 ` Jiri Pirko
2019-11-08 18:23 ` Parav Pandit
2019-11-08 18:34 ` Jiri Pirko
2019-11-08 18:56 ` Parav Pandit
2019-11-08 9:30 ` Jiri Pirko
2019-11-08 15:41 ` Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 13/19] net/mlx5: Register SF devlink port Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 14/19] net/mlx5: Share irqs between SFs and parent PCI device Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 15/19] net/mlx5: Add load/unload routines for SF driver binding Parav Pandit
2019-11-08 9:48 ` Jiri Pirko
2019-11-08 11:13 ` Jiri Pirko
2019-11-07 16:08 ` [PATCH net-next 16/19] net/mlx5: Implement dma ops and params for mediated device Parav Pandit
2019-11-07 20:42 ` Jakub Kicinski
2019-11-07 21:30 ` Parav Pandit
2019-11-08 1:16 ` Jakub Kicinski
2019-11-08 6:37 ` Christoph Hellwig
2019-11-08 15:29 ` Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 17/19] net/mlx5: Add mdev driver to bind to mdev devices Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 18/19] Documentation: net: mlx5: Add mdev usage documentation Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 19/19] mtty: Optionally support mtty alias Parav Pandit
2019-11-08 6:26 ` Leon Romanovsky
2019-11-08 10:45 ` Jiri Pirko
2019-11-08 15:08 ` Parav Pandit
2019-11-08 15:15 ` Jiri Pirko
2019-11-08 13:46 ` Cornelia Huck
2019-11-08 15:10 ` Parav Pandit
2019-11-08 15:28 ` Cornelia Huck
2019-11-08 15:30 ` Parav Pandit
2019-11-08 17:54 ` Alex Williamson
2019-11-08 9:51 ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Jiri Pirko
2019-11-08 15:50 ` Parav Pandit
2019-11-07 17:03 ` [PATCH net-next 00/19] Mellanox, mlx5 sub function support Leon Romanovsky
2019-11-07 20:10 ` Parav Pandit
2019-11-08 6:20 ` Leon Romanovsky
2019-11-08 15:01 ` Parav Pandit
2019-11-07 20:32 ` Jakub Kicinski
2019-11-07 20:52 ` Parav Pandit
2019-11-08 1:16 ` Jakub Kicinski
2019-11-08 1:49 ` Parav Pandit
2019-11-08 2:12 ` Jakub Kicinski
2019-11-08 12:12 ` Jiri Pirko
2019-11-08 14:40 ` Jason Gunthorpe
2019-11-08 15:40 ` Parav Pandit
2019-11-08 19:12 ` Jakub Kicinski
2019-11-08 20:12 ` Jason Gunthorpe
2019-11-08 20:20 ` Parav Pandit
2019-11-08 20:32 ` Jason Gunthorpe
2019-11-08 20:52 ` gregkh
2019-11-08 20:34 ` Alex Williamson
2019-11-08 21:05 ` Jason Gunthorpe
2019-11-08 21:19 ` gregkh
2019-11-08 21:52 ` Alex Williamson
2019-11-08 22:48 ` Parav Pandit
2019-11-09 0:57 ` Jason Gunthorpe
2019-11-09 17:41 ` Jakub Kicinski
2019-11-10 19:04 ` Jason Gunthorpe
2019-11-10 19:48 ` Parav Pandit
2019-11-11 14:17 ` Jiri Pirko
2019-11-11 14:58 ` Parav Pandit
2019-11-11 15:06 ` Jiri Pirko
2019-11-19 4:51 ` Parav Pandit
2019-11-09 0:12 ` Jason Gunthorpe
2019-11-09 0:45 ` Parav Pandit
2019-11-11 2:19 ` Jason Wang
2019-11-08 21:45 ` Jakub Kicinski
2019-11-09 0:44 ` Jason Gunthorpe
2019-11-09 8:46 ` gregkh
2019-11-09 11:18 ` Jiri Pirko
2019-11-09 17:28 ` Jakub Kicinski
2019-11-10 9:16 ` gregkh
2019-11-09 17:27 ` Jakub Kicinski
2019-11-10 9:18 ` gregkh
2019-11-11 3:46 ` Jakub Kicinski
2019-11-11 5:18 ` Parav Pandit
2019-11-11 13:30 ` Jiri Pirko
2019-11-11 14:14 ` gregkh
2019-11-11 14:37 ` Jiri Pirko
2019-11-10 19:37 ` Jason Gunthorpe
2019-11-11 3:57 ` Jakub Kicinski
2019-11-08 16:06 ` Parav Pandit
2019-11-08 19:06 ` Jakub Kicinski
2019-11-08 19:34 ` Parav Pandit
2019-11-08 19:48 ` Jakub Kicinski
2019-11-08 19:41 ` Jiri Pirko
2019-11-08 20:40 ` Parav Pandit
2019-11-08 21:21 ` Jakub Kicinski
2019-11-08 21:39 ` Jiri Pirko [this message]
2019-11-08 21:51 ` Jakub Kicinski
2019-11-08 22:21 ` Jiri Pirko
2019-11-07 23:57 ` David Miller
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