* Re: thunderbolt_net performance and receive-side-scaling (RSS)
[not found] <CAOhm4wpO9gB03qt0kPdEiZtKLD_UOuYx=VbQVWwyXmqS_0_ySA@mail.gmail.com>
@ 2026-03-05 9:06 ` Mika Westerberg
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From: Mika Westerberg @ 2026-03-05 9:06 UTC (permalink / raw)
To: Oddbjørn Kvalsund; +Cc: netdev, Mika Westerberg
Hi,
On Thu, Mar 05, 2026 at 09:56:26AM +0100, Oddbjørn Kvalsund wrote:
> Hi,
>
> I am seeing fairly good network performance between a 2018 Dell XPS15 laptop
> and a 2021 MacBook using Thunderbolt and the thunderbolt_net driver, with jumbo
> frames enabled on both machines (iperf3 results below). However, while iperf3
> is running, one core on the XPS15 is at 100% utilization due to the ksoftirqd
> process. This makes me wonder whether additional performance could be achieved
> if the load were distributed across multiple cores.
>
> From what I can tell, this might relate to receive-side scaling (RSS), which
> does not appear to be implemented in the thunderbolt_net driver. Would adding
> RSS support be worthwhile, or are there architectural limitations that would
> make such an optimization ineffective?
I'm not familiar with that but feel free to experiment and if you find that
it provides better throughput please provide patches :)
USB4NET spec can be downloaded from USB-IF, it's part of USB4 spec.
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