Linux on C7gd with ENA: HW Packet Timestamping / SOF_TIMESTAMPING_RX_HARDWARE support

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Hi.

With the C7gd instances, the ENA NIC offers a PTP clock source and a timestamping service[1]. Both work very well as documented. We were hoping to also have ENA timestamp incoming packets on the NIC using the same clocksource (see Kernel Timestamping / SOF_TIMESTAMPING_RX_HARDWARE [2] [3]). Unfortunately that option does not appear to exist:

Does anyone know if other instance types have this capability or, if not, if there are any plans to add this?

Thanks for any input, Daniel

[1] https://aws.amazon.com/blogs/compute/its-about-time-microsecond-accurate-clocks-on-amazon-ec2-instances/ [2] https://docs.kernel.org/networking/timestamping.html [3] https://netdevconf.info/0x17/docs/netdev-0x17-paper23-talk-slides/netdevconf%202023_%20SO_TIMESTAMPING.pdf

asked a month ago30 views
1 Answer
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The ENA (Elastic Network Adapter) on C7gd instances does indeed provide a PTP (Precision Time Protocol) clock source and timestamping service. However, the specific capability you're asking about - hardware packet timestamping for incoming packets (SOF_TIMESTAMPING_RX_HARDWARE) - is not currently supported on C7gd instances.

As of now, there is no information available about other instance types that support this specific hardware packet timestamping feature for incoming packets. The PTP hardware clock functionality is available on several instance families, including compute-optimized instances like C7gd, C7i, and C8g, but this doesn't necessarily mean they support the SOF_TIMESTAMPING_RX_HARDWARE feature.

The availability of hardware features can vary across different instance types and families. AWS regularly introduces new features and capabilities to their instance types, but there's no public information about specific plans to add this particular hardware packet timestamping feature.

If this feature is critical for your use case, you might want to reach out to AWS support directly. They may be able to provide more detailed information about current capabilities across different instance types or potential future plans for this feature. Additionally, they could potentially help you explore alternative solutions or workarounds that might meet your needs.

It's worth noting that while hardware timestamping for incoming packets isn't currently available, the existing PTP clock source and timestamping service on C7gd instances still provide highly accurate time synchronization, which may be sufficient for many use cases requiring precise timing.
Sources
It’s About Time: Microsecond-Accurate Clocks on Amazon EC2 Instances | AWS Compute Blog
Set the time reference on your EC2 instance to use the local Amazon Time Sync Service - Amazon Elastic Compute Cloud

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answered a month ago

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