On Wed, May 1, 2013 at 12:50 AM, Simon Horman <ho...@verge.net.au> wrote: > On Tue, Apr 30, 2013 at 09:19:51AM -0700, Jesse Gross wrote: >> On Mon, Apr 29, 2013 at 8:21 PM, Simon Horman <ho...@verge.net.au> wrote: >> > On Fri, Apr 26, 2013 at 04:03:21PM -0700, Jesse Gross wrote: >> >> On Thu, Apr 25, 2013 at 12:36 AM, Simon Horman <ho...@verge.net.au> wrote: >> >> > On Tue, Apr 23, 2013 at 02:00:19PM -0700, Joseph Gasparakis wrote: >> >> >> Any particular reason to introduce skb->encapsulation_features instead >> >> >> of >> >> >> using the existing skb->encapsulation? Also I don't see it used in your >> >> >> second patch either. >> >> > >> >> > My reasoning is that skb->encapsulation seems to alter the behaviour of >> >> > many different locations and I'm not sure that any of them, other than >> >> > the >> >> > one in dev_hard_start_xmit() make sense for MPLS. >> >> >> >> The problem is the meaning of skb->encapsulation isn't really defined >> >> clearly and I'm certain that the current implementation is not going >> >> to work in the future. Depending on your perspective, vlans, MPLS, >> >> tunnels, etc. can all be considered forms of encapsulation but clearly >> >> there are many NICs that have different capabilities across those. I >> >> believe the intention here was really to describe L3 tunnels as >> >> encapsulation, in which case MPLS really shouldn't be using this >> >> mechanism at all. >> >> >> >> Now there is some overlap, especially today since most currently >> >> shipping silicon wasn't designed to support tunnels and so is using >> >> some form of offset based offloads. In that case, all forms of >> >> encapsulation are pretty similar. However, in the future that won't be >> >> the case as support for specific protocols is implemented for higher >> >> performance and richer support. When that happens, not only will MPLS >> >> and tunnels have different capabilities but various forms tunnels >> >> might as well. >> > >> > Wouldn't be possible to describe those differences using, >> > dev->hw_enc_features? I assumed that was its purpose. >> >> If there truly are differences between the offload capabilities of >> MPLS and L3 tunnels then no, it's not possible, because it's a single >> field. It's certainly not a valid assumption that a NIC that can do >> TSO over GRE can also do it over MPLS. >> >> However, it's unlikely that there are truly significant differences >> between various encapsulation formats on a per-feature basis. I think >> what we need to do is separate out the ability to understand the >> headers from the capabilities so you have two fields: header (none, >> VLAN, QinQ, MPLS, VXLAN, GRE, etc.) and feature (checksum, SG, TSO, >> etc.) rather than the product of each. Otherwise, we end up with a ton >> of different combinations. > > I'm not quite sure that I follow. > > Is your idea to replace skb->encapsulation (a single bit) with > a field that corresponds to the outer-most (encapsulation) header in use > and has bits for none, VLAN, QinQ, MPLS, VXLAN, GRE, etc...?
No, I'm talking about netdev features. You can already tell the encapsulation type of a packet by looking at the EtherType. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
