Re: Containernet (Docker/Container Networking) with DPDK?

[Thea Corinne Rossman <thea.rossman@cs.stanford.edu>]

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This is SO helpful -- thank you so much.

One follow-up question regarding NICs: can multiple containers on the same
host share the same PCI device? If I have a host NIC with (say) VFIO driver
binding, do I have to split it with some kind of SR-IOV so that each
container has its own "NIC" binding? Or, when running DPDK's "devbind"
script, can I set up each one with the same PCI address?

On Tue, Nov 19, 2024 at 1:29 PM Stephen Hemminger <
stephen@networkplumber.org> wrote:

> On Tue, 19 Nov 2024 12:53:02 -0800
> Thea Corinne Rossman <thea.rossman@cs.stanford.edu> wrote:
>
> > I'm following up on this to ask a more specific question, since my first
> > question was a bit all over the place. This is regarding the interplay
> > between the host and the containers when setting up containers that can
> run
> > DPDK applications.
> >
> > Based on what I've found so far, it looks like I will have to fully
> > configure DPDK on the host and then mount devices onto each container,
> even
> > if there's no need to connect the containers to the outside world. (Is
> this
> > correct?) If so, I don't fully understand this, since a
> container/container
> > network should be self-contained.
> >
> >    - Why do we need to set up DPDK on the host? (Why isn't the container
> >    enough?)
> >    - Why do we need to set up a DPDK-compatible driver on the host NICs?
> If
> >    the containers are on the same machine, exchanging packets, why would
> the
> >    host NIC be involved at all? Nothing is going in or out.
> >    - Why do we need to configure hugepages on the host and then mount
> them
> >    on the container? Why can't you just configure this on the
> containers? Is
> >    this something that can't be emulated?
> >
>
> Containers are a made up construct. They are made by setting permissions
> for
> namespaces and groups for resources.
>
> In most cases, DPDK works by passing through the raw hardware (PCI device)
> to the userspace application. To make it work with a container system you
> need to either acquire the resource in an restricted environment and then
> allow access to that resource in the restricted container; or you need
> to give the restricted container environment lots of privileges to
> configure
> and setup the raw hardware directly. In the latter case, there really is
> no point in having containers.
>
> Same applies to hugepages.  I don't think hugepages are namespaced either.
>

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