RFC: support for TCP Segmentation Offloading (TSO) #830
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In case of TSO support, the NIC divides larger data chunks into TCP segments. To support TSO, the `DeviceCapabilities` is extended with `TsoCapabilities`. It can describe, if TSO supported for IPv4, IPv6 or both. In case TSO is supported, smoltcp emits packts with the maximum size of the remote window to the device driver.
whitequark
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Aug 13, 2023
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The functionality looks fine to me. I'll leave style comments to @Dirbaio.
Co-authored-by: Catherine <whitequark@whitequark.org>
Co-authored-by: Catherine <whitequark@whitequark.org>
the Virtio specification defines 65550 as maximum packet size
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Ok, I found some issues. I have to think about it. |
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I tried to extend a driver to support TCP segmentation offloading (TSO). In this case, smoltcp has to create one header (Ethernert+IP+TCP) followed by multiple payloads. To support TSO, I extended the
DeviceCapabilitieswithTsoCapabilities.TsoCapabilitiescan describe, if TSO is supported for IPv4, IPv6 or both. In case TSO is supported, smoltcp emits packets with the maximum size of the remote window to the device driver.Maybe my solution is a little bit naive. I am not an TCP expert. My test driver is a revised driver for Virtio. Consquently, my VM uses virtio to forward messages to a tap device. Afterwards, the host forwards the packets over a 10 Gbit/s device to a server, which sends a response back. Both devices (tap and the ethernet device) supports TSO. I monitored the communication with Wireshark. It seems to work and I don't see any strange behavior.
I would appreciate comments to improve my work.