On Tue, Jul 26, 2016 at 10:06 AM, Jesse Gross <je...@kernel.org> wrote: > On Mon, Jul 25, 2016 at 5:49 PM, Pravin B Shelar <pshe...@ovn.org> wrote: >> OVS compat layer can handle tunnel GSO packets. but it does >> keep skb encapsulation on for packet handled in GSO. This can >> confuse some NIC drivers. I have seen this issue on intel devices: >> >> i40e 0000:42:00.0: TX driver issue detected, PF reset issued >> >> Following patch resets this bit in case compat layer handles the packet. >> >> VMware-BZ: 1698877 >> Signed-off-by: Pravin B Shelar <pshe...@ovn.org> > > In upstream, this is done as part of the GSO code (for example, in > __skb_udp_tunnel_segment()) so that probably makes more sense and is > safer if this is GSO specific. There is already code in > ovs_iptunnel_handle_offloads() that will clear the encapsulation bit > in the case of checksum offload on the outer header. > ovs_iptunnel_handle_offloads() is not equivalent to skb_udp_tunnel_segment(). If handle-offload clear the bit it would not be possible to check the encapsulation bit after handle-offload call in tunnel implementation. At this point this bit is not checked, so it is not issue. But that would be different behavior compared to upstream.
> One minor comment - skb->encapsulation is actually a u8 field instead > of a bool, so setting it to 0 rather than false is more consistent > with the rest of the kernel. > ok. > Something that I noticed while looking at this is it looks like the > recent patch that moved the check for gso_type_mask into a GSO-only > block in ovs_iptunnel_handle_offloads() might cause a bit of a > performance regression. Even though that field is GSO-specific, it is > also used to control whether we resolve partial checksums. Even in > cases where we do need to use the OVS offload compat code, I suspect > we could take better advantage of hardware offloads - not computing > the checksum when !skb->encapsulation (since every kernel can do UDP > checksum offload), using scatter/gather in GSO, checking for backport > support when clearing type in rpl_udp_tunnel_handle_offloads(). I am not sure I understand it correctly. the recent change actually using compat gso code only for GSO packet, earlier it was using it for non GSO packets too. By not setting "OVS_GSO_CB(skb)->fix_segment" we are using networking stack. Anyways I am have couple of ideas in this area to use hardware offload more effectively. I will send patches for it. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
