Re: [PATCH v6 net-next 13/13] mlx5: support BIG TCP packets

On 12 May 11:02, Paolo Abeni wrote:

On Thu, 2022-05-12 at 01:40 -0700, Saeed Mahameed wrote:

quoted

On 09 May 20:32, Eric Dumazet wrote:

quoted

From: Coco Li <redacted>

mlx5 supports LSOv2.

IPv6 gro/tcp stacks insert a temporary Hop-by-Hop header
with JUMBO TLV for big packets.

We need to ignore/skip this HBH header when populating TX descriptor.

Sorry i didn't go through all the documentations or previous discussions,
please bare with me, so why not clear HBH just before calling the
driver xmit ndo ?

I guess this way is more efficient: the driver copies IP hdr and TCP
hdr directly in the correct/final location into the tx descriptor,
otherwise the caller would have to memmove L2/L3 just before the driver
copies them again.

quoted

memmove(sizeof(L2/L3)) is not that bad when done only every 64KB+.
it's going to be hard to repeat this and maintain this across all drivers
only to get this micro optimization that I doubt it will be even measurable.

quoted

Or if HBH has to stick, 

My understanding is that this is not the case.

Cheers,

Paolo