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@xxxxxxxxxx> 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.
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
