Re: [PATCH] Ethernet Bridging: Enable Hardware Checksumming

[Nivedita Singhvi <niv@us.ibm.com>]

Herbert Xu wrote:

> Jon Mason <jdmason@us.ibm.com> wrote:
> 
>>checksum and scatter gather as features of the bridge device.  In the 
>>case that the physical ethernet device does not support scatter 
>>gather or hardware checksum, dev_queue_xmit() will check the
>>dev->features and do the necessary linearization and calculate the
>>checksum.
> 
> 
> Unfortunately skb_linearize is a lot more expensive than not
> generating the non-linear skb's in the first place.
> 
> So this is going to hurt people using the bridge devices over
> physical devices that don't support SG.

Fair point - though I would argue that devices that
support SG are much more common now - so optimizing
for the more common case might be preferable - since
people using bridging with devices that support
checksum offload are taking quite a hit when they
do bridging - perhaps this could be a conditional?

thanks,
Nivedita