On Wed, Dec 08, 2021 at 04:56:52PM +0000, Alex Benn??e wrote:

Hi,

So the following is what I had in my head for a demo setup based on what we talked about this morning. Does it make sense?

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                STRATOS TSN NETWORKING WITH VMS

                          Alex Bennée
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Table of Contents ─────────────────

1. Abstract

.. 1. Hardware .. 2. Setup

1 Abstract ══════════

In a multi-zone/multi-VM setup it is important that higher priority (i.e. safety critical) workloads are not impaired by lower priority ones. In a modern automotive setup which was using something like ethernet to link a number of units we need to ensure the networking also allows for effective and timely delivery of important packets.

This demo intends to show how Time Sensitive Networking (TSN) can be combined with an accelerated AF_XDP path from host to guest to ensure correct behaviour. The primary guest will be injesting a video stream which represents a reversing camera which has low latency requirements while a second guest loads a large amount of mapping data for a navigation app. We will run two scenarios. The first will use in-kernel TSN support using software to handle the packet scheduling. The second will use dedicated HW with TSN support which should achieve much lower latency than relying on SW.

1.1 Hardware ────────────

• 2 x Machiatobin with 10G copper SFP • 2 x PCIe network cards with TSN offload (Intel I255 or equivalent) • 1 x PCIe video card • 1 x USB Audio

1.2 Setup ─────────

The setup is the same as used for previous AF_XDP measurements except that *ethT* is either using the builtin SoC networking or the TSN accelerated PCIe network device.

The target machine (representing a automotive display console) runs two VMs. A low priority one for the navigation function which is fetching large amounts of none time critical data for the map display. The higher priority VM receives and decompressed the state of the reversing camera.

I found a good introduction of TSN (with a bunch of detailed instructions) specifically for AV demo: https://tsn.readthedocs.io/avb.html # Please note that AVB is a predecessor of TSN standard and originally # advocated by automotive industry IIUC.

Given that we have a good document like the above, someone should have already done some evaluation, at least, on physical machines.

Both VMs display their output via an virtio-gpu device which is composited to a single display on the host. For simplicity we shall assume KVM virtualisation.

Virtio-gpu is good for demo, but it has nothing to do with network performance.

-Takahiro Akashi

-- Alex Bennée