[ovs-dev] [Single DP 08/15] Separate OpenFlow port numbers from datapath ones.

Ben Pfaff blp at nicira.com
Wed Oct 31 04:05:49 UTC 2012

On Tue, Oct 30, 2012 at 03:34:32PM -0700, Justin Pettit wrote:
> On Oct 22, 2012, at 3:11 PM, Ben Pfaff <blp at nicira.com> wrote:
> > We want to avoid quickly reusing OpenFlow port numbers.  Previously,
> > that was indirectly implemented through dpif-linux, which makes an
> > effort to avoid quickly reusing kernel datapath port numbers.  This
> > commit defeats that, I think, by generally allocating the
> > lowest-numbered available OpenFlow port number.  Presumably we should
> > remove the reuse-avoidance logic from dpif-linux and move it to
> > ofproto?
> Good point.  I added some logic to ofproto, but I didn't remove the
> logic from dpif-linux, since it's not required for this patch.  Do you
> think it's worth creating a new patch that always looks for the lowest
> numbered free port instead?

We can do it as a separate patch.  It should mostly be a matter of
removing code: if we don't request a particular port number the kernel
will select the lowest free port number for us.

> > Should port_dump_next() skip and warn about ports for which
> > odp_port_to_ofp_port() returns OFPP_NONE?
> I don't know that that would work properly, since init_ports() calls
> the port iterator on startup--before we've assigned OpenFlow port
> numbers.  We could work around this, but I'm not sure it's worth it
> for a sanity-check.  Thoughts?

I didn't realize there was a valid situation where this could happen.
Skip it.

> > I'm a little uncomfortable with this but I can't quite put a finger on
> > the issue, so I'll defer further review of it for the moment.
> Do you have any new thoughts on the patch?

No revelations have come to light, so let's call it good.

More information about the dev mailing list