Re: [net-next 01/13] ixgbe: Add support for IPv6 and UDP to ixgbe_get_headlen

[Eric Dumazet <eric.dumazet@gmail.com>]

On Fri, 2012-10-19 at 23:25 -0700, Jeff Kirsher wrote:
> From: Alexander Duyck <alexander.h.duyck@intel.com>
> 
> This change adds support for IPv6 and UDP to ixgbe_get_headlen. The
> advantage to this is that we can now handle ipv4/UDP, ipv6/TCP, and
> ipv6/UDP with a single memcpy instead of having to do them in multiple
> pskb_may_pull calls.
> 
> A quick bit of testing shows that we increase throughput for a single
> session of netperf from 8800Mpbs to about 9300Mpbs in the case of ipv6/TCP.
> As such overall ipv6 performance should improve with this change.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Tested-by: Stephen Ko  <stephen.s.ko@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)

Thats pretty interesting.

Why this work is not done generically, so that all drivers can have
benefit of it ?

Even a driver not using fragments could have benefit, because we could
prefetch() so that GRO stack is faster (no stall to get the last 2 bytes
of a TCP header when timestamps are used)

Thanks