[talawahtech]

All the 16 vCPU "n" instances (m5n, c5n, r5n, etc) are capable of hitting the 25 Gbps limit easily. In your report, all of the AWS results are limited to either 5Gbps or 10Gbps, but this is because of a very specific test condition.

From my understanding of the test scenario, you are using a single TCP connection to run the throughput test, and hitting AWS' documented[1] throughput limit for a single flow: 10 Gbps if the two instances are in the same placement group and 5 Gbps otherwise. The reason some of the network-optimized instances were "slower" than the non-optimized ones is most likely a random draw of whether both instances in the test were physically close to each other (basically whether or not they are accidentally in placement groups).

To show the true throughput you would need to use multiple connections/flows, 5-10 would probably suffice. If the single flow test case was important then maybe you should have mentioned that AWS has a specific limitation around this. Personally I don't think a single flow test case is particularly realistic for a throughput test. Either way, how it is presented is pretty misleading.

1. "Single TCP flow is limited to 10 Gbps for instances in the same placement group and 5 Gbps between instances anywhere else." https://docs.aws.amazon.com/whitepapers/latest/ec2-networkin...

[sknat]

Right, this also aligns with the our testing. Number of queues available seem to also be playing a role. But you're right RSS should spread traffic quite nicely when using 5-10 flows.

[deadmutex]

Do you know why they place this limit?