On 9/14/26 11:16 PM, Ilya Maximets wrote:
> On 9/10/26 3:16 PM, Wang Zhan wrote:
>> Set the internal port TSO limit to GSO_MAX_SIZE (512 KB), as for
>> loopback and veth. This allows the admin/user to set a GSO limit up to
>> this value, to use BIG TCP for traffic routed through the internal port.
>>
>> Only the capability limit changes: the IPv4 and IPv6 GSO and GRO limits
>> remain at 64 KiB until changed by the administrator.
>>
>> Validation used a same-host test with a temporary OVS bridge, a veth pair,
>> and a network namespace:
>>
>>   TCP client -> OVS internal -> OVS bridge -> veth -> TCP server
>>
>> The veth endpoints were BIG TCP capable throughout the test, and only the
>> OVS internal port limits changed between 64 KiB and 524280 bytes. A single
>> iperf3 3.19 TCP flow, run separately over IPv4 and IPv6 with six
>> alternating runs per state (`-t 15 -O 5`, fixed CPU affinity and port
>> tuple), increased throughput by 18.1% for IPv4 and 34.7% for IPv6:
>>
>>   protocol  BIG TCP off  BIG TCP on   CV off / on
>>   TCP/IPv4  65.567 Gbps  77.420 Gbps  1.12% / 0.37%
>>   TCP/IPv6  55.355 Gbps  74.568 Gbps  1.20% / 0.68%
>>
>> Assisted-by: LLM
>
> This looks a bit strange.

Do you mean the "Assisted-by: LLM" tag? I used AI assistance for
building, testing, and patch preparation, so I added the tag following:
https://docs.kernel.org/process/coding-assistants.html#attribution

> Please, add an empty line here, it looks awkward to glue the call
> to the feature flags block.
>
>> +    netif_set_tso_max_size(netdev, GSO_MAX_SIZE);

Okay, will fix in v2.

> The packets will be segmented before sending to userspace or ports that
> do not support BIG TCP and all the functions that check the packet length
> supposed to use gso_size and not the raw length.

Right, and that's mostly fine. There is one catch though: when a BIG TCP
packet goes to a port without BIG TCP support, it currently gets segmented
to MTU and the GSO flag is dropped, which can regress performance pretty
badly. I'm preparing a follow-up patch to segment to the target GSO size
instead. Not a blocker for this patch.

> But, please, CC all the maintainers while sending patches.

Okay, will do.

Thanks for the review.

Best regards, Wang Zhan.
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