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

Yuval Shaia
2015-07-30T20:46:36Z

On Thu, Jul 30, 2015 at 11:15:38AM -0600, Jason Gunthorpe wrote:
> 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.
The current approach is to utilize IPoIB's private-data to exchange this
information.
>
> 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
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