Re: [RFC PATCH 3/3] x86/lib: Use EGPRs in 64-bit checksum copy loop

[Chang S. Bae]

On 11/25/2025 2:37 AM, david laight wrote:
> This code (or something very similar) gets used to checksum data
> during copy_to/from_user for sockets.
> This goes back a long way and I suspect the 'killer ap' was nfsd
> running over UDP (with 8k+ UDP datagrams).
> Modern NICs all (well all anyone cares about) to IP checksum offload.
> So you don't need to checksum on send() - I'm sure that is still
> enabled even though you pretty much never want it.
> The checksum on recv() can only happen for UDP, but massively
> complicates the code paths and will normally not be needed.

It sounds like this optimization wouldn't provide practical benefit. I 
don't see a strong case for pursuing this further either, so I'd drop this.

Thanks,
Chang