On Thu, May 02, 2013 at 09:53:25AM -0700, Jesse Gross wrote: > On Wed, May 1, 2013 at 10:31 PM, Simon Horman <ho...@verge.net.au> wrote: > > On Wed, May 01, 2013 at 09:53:42PM -0700, Jesse Gross wrote: > >> On Wed, May 1, 2013 at 3:57 PM, Simon Horman <ho...@verge.net.au> wrote: > >> > On Wed, May 01, 2013 at 11:16:40AM -0700, Jesse Gross wrote: > >> >> 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. > >> > > >> > Now I am completely confused about what are the two fields that you > >> > refer to in your previous email. > >> > >> I have always been referring to the netdev features for various > >> protocol types. This is because considering MPLS as a form of > >> encapsulation for the purpose of offloads buckets too many protocols > >> into the same set and NICs will have varying features for those. > >> Trying to avoid this by having a bit for offloadable encapsulations is > >> just going to be very confusing and not very future proof. > >> > >> > In regards to looking ath the ethernet type: > >> > > >> > One of the tricky parts of MPLS is that the packet itself does not > >> > contain > >> > the ethernet type or any other way of knowing the type of the > >> > inner-packet. > >> > Information that is needed for GSO. > >> > >> I'm aware of that. However, you were referring to the type of > >> encapsulation. It is easy to determine that a packet is MPLS. > >> > >> > My proposal to get around this is to leave skb->protocol as the > >> > original, in the case we are interested in non-MPLS, ethernet type. > >> > >> At the very least, this is not consistent with how it is currently > >> handled (for example, with VLANs) and seems difficult to do properly. > >> However, I have not seen any further analysis since the last time that > >> we discussed this. > > > > Unfortunately my efforts to solicit feedback from others regarding > > that have not been successful. > > Give me a break, Simon. These are your patches and therefore it is > your responsibility to do the analysis. This has come up over and over > again and I'm not happy about it. > > Rather than trying to respond to me as quickly as possible, you need > to slow down, take a step back, and think about the correct direction. > Given that some of these patches have revision numbers in the 20s you > have nothing to complain about as far as receiving help. > > In order to assist you in this, I'm going to drop all of your pending > patches from my queue and not respond to anything further from you > until the merge window is open again.
I apologise, the comment I made above was unnecessary. I accept your criticism in regards to responding to quickly. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
