[ovs-discuss] question about facet and subfacet in the code

Feixiong Zhang feixiong at winlab.rutgers.edu
Thu Jul 11 17:05:52 UTC 2013


Hi, Justin,

thanks for your reply.

I'm looking at code from
http://openvswitch.org/releases/openvswitch-1.9.0.tar.gz. So the code on
facet has changed to comply with wildcard in the newest branch? Which
branch do you recommend to use? I see that 1.9.0 is long term supported
release.

Thanks.
Feixiong


On Thu, Jul 11, 2013 at 11:58 AM, Justin Pettit <jpettit at nicira.com> wrote:

> Your description sounds correct for megaflows (branch-1.11 and master),
> but your code walk-through sounds like it was for an older branch.
>
> --Justin
>
>
> On Jul 11, 2013, at 7:36 AM, Feixiong Zhang <feixiong at winlab.rutgers.edu>
> wrote:
>
> > hello, everyone,
> >
> > I'm looking at the implementation of openvswitch and is confused about
> facet and subfacet. From previous posts, facet represents user space flow
> with wildcard, while subfacet stands for kernel space flow concept with no
> wildcard. Thus a facet consists of multiple subfacets.
> >
> > However, in the implementation,
> > facet_create(rule, &miss->flow, hash) in handle_flow_miss() will create
> a facet with miss->flow as the key. But miss->flow is from kernel datapath
> and doesn't contain wildcard.
> > Moreover, facet_find() uses flow_equal(flow, &facet->flow) to determine
> whether a facet match the flow, and flow_equal() will check all the field
> in the struct flow. And facet_find() is almost the same as
> subfacet_find__(), both uses flow_equal().
> > It seems in the implementation, facet also relies on exact match of all
> fields, same as subfacet.
> >
> > I'm not sure whether I understand correctly. Can anyone clarify on this?
> Thanks a lot!
> >
> > Regards.
> > Feixiong
> > _______________________________________________
> > discuss mailing list
> > discuss at openvswitch.org
> > http://openvswitch.org/mailman/listinfo/discuss
>
>
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