Re: [PATCH] IB/ipoib: CSUM support in connected mode

Jason Gunthorpe
2015-07-30T17:15:38Z

On Thu, Jul 30, 2015 at 11:51:12AM -0400, Doug Ledford wrote:

> In its current state, I have my doubts about this patch. However, it
> seems to me that this should be relatively easy to fix in such a way
> that you get 90%+ of the performance benefit, and can turn it on by
> default, and we don't cause any problems.

The best way to implement this is to leverage all the checksum
offload work people did for virtualization.

Forward the checksum offload status through the RC connection and
recover it on the other side.

Then the far side stack will know it is dealing with a partial
checksum packet and will properly regenerate the checksum if it
re-transmits.

ie doing it this way doesn't totally break the netstack :)

Jason