On Oct 30, 2014, at 1:43 PM, Ben Pfaff <b...@nicira.com> wrote: > On Thu, Oct 30, 2014 at 08:26:15AM -0700, Ben Pfaff wrote: >> On Thu, Oct 30, 2014 at 12:06:30PM +0100, Thomas Graf wrote: >>> On 10/29/14 at 11:46pm, Ben Pfaff wrote: >>>> A "conjunctive match" allows higher-level matches in the flow table, such >>>> as set membership matches, without causing a cross-product explosion for >>>> multidimensional matches. Please refer to the documentation that this >>>> commit adds to ovs-ofctl(8) for a better explanation, including an example. >>> >>> High level remark before I dig into the code: >>> >>> conjunction(id, k/n) >>> >>> I like n being the number of dimensions. I wonder whether we should >>> have k start at 1 instead of 0 though. It would read as 1/2 - "1st >>> dimension out of 2", 2/2 - "2nd dimension out of 2". >> >> I'd be happy with that as the formatted syntax, but due to the use of >> bitmaps for the dimensions it would either cause extra +1/-1 in >> different places, or change the limit from 64 to 63 dimensions (which is >> probably still about 60 more than actually useful). >> >> I'll think about it for the next version. > > I decided to change the formatted representation but not the OpenFlow > binary format; that is, the formatting and parsing code for the > human-readable representation adds or subtracts one from the dimension > numbers. > > This change will be in the next version I post. > >>>> - Fixing reg0 as the field to use for conjunctive match lookup doesn't seem >>>> too great. We could make it configurable per-flow, or we could add a new >>>> field specifically for this purpose. I am not sure that it should be >>>> fixed to 32 bits, either. >>> >>> I guess we can't go wrong with a separate 64 bits field. >> >> We're starting to have a lot of fields. When struct flow exceeds 252 >> (63 * 4) bytes, we'll have to change how struct miniflow works because >> we can't make the 'map' member wider than 63 bits. Still, we do have >> some room. > > Jarno also suggested using a dedicated field, so I went with that. At > the moment it is 32 bits. That would not be difficult to change, but > it would extend NXAST_CONJUNCTION from 16 to 24 bytes.
Controllers are free to use all the additional metadata fields in the conjunction rules as well to scope them down to a specific VNI, for example. So a VNI need not be embedded into the conjunction field. Jarno _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
