Re: [PATCH net-next v4 0/2] net/mlx5: Avoid payload in skb's linear part for better GRO-processing

[Tariq Toukan <ttoukan.linux@gmail.com>]

On 30/08/2025 1:43, Saeed Mahameed wrote:
> On 28 Aug 20:36, Christoph Paasch via B4 Relay wrote:
>> When LRO is enabled on the MLX, mlx5e_skb_from_cqe_mpwrq_nonlinear
>> copies parts of the payload to the linear part of the skb.
>>
>> This triggers suboptimal processing in GRO, causing slow throughput,...
>>
>> This patch series addresses this by using eth_get_headlen to compute the
>> size of the protocol headers and only copy those bits. This results in
>> a significant throughput improvement (detailled results in the specific
>> patch).
>>
>> Signed-off-by: Christoph Paasch <cpaasch@openai.com>
> 
> LGTM, I would love to take this to net-next-mlx5 and submit it back to
> netdev after regression testing if that's ok? Christoph? Anyway I will 
> wait for Jakub to mark this as "awaiting-upstream" or if he
> applies it directly then fine.
> 
> 
> 

Hi,

I recall trying out similar approach internally a few years ago.

eth_get_headlen() function didn't work properly for non-Eth frames 
(ipoib). I believe this is still the case.

Extra care is needed for the ipoib flow, which I assume gets broken here.

According to the perf gain, it is worth splitting to multiple code paths 
via branches/function pointers.

Regards,
Tariq