On Aug 9, 2016 8:28 PM, "Ryan Moats" <rmo...@us.ibm.com> wrote:
>
> Numan Siddique <nusid...@redhat.com> wrote on 08/09/2016 09:39:21 AM:
>
> > From: Numan Siddique <nusid...@redhat.com>
> > To: Ryan Moats/Omaha/IBM@IBMUS
> > Cc: ovs dev <dev@openvswitch.org>
> > Date: 08/09/2016 09:39 AM
> > Subject: Re: [ovs-dev] [PATCH] ovn-controller: Reset flow processing
> > after (re)connection to switch
>
> >
> > On Tue, Aug 9, 2016 at 7:15 PM, Ryan Moats <rmo...@us.ibm.com> wrote:
> > "dev" <dev-boun...@openvswitch.org> wrote on 08/09/2016 07:19:27 AM:
> >
> > > From: Numan Siddique <nusid...@redhat.com>
> > > To: ovs dev <dev@openvswitch.org>
> > > Date: 08/09/2016 07:19 AM
> > > Subject: [ovs-dev] [PATCH] ovn-controller: Reset flow processing
> > > after (re)connection to switch
> > > Sent by: "dev" <dev-boun...@openvswitch.org>
> > >
> > > When ovn-controller reconnects to the ovs-vswitchd, it deletes all the
> > > OF flows in the switch. It doesn't install the flows again, leaving
> > > the datapath broken unless ovn-controller is restarted or ovn-northd
> > > updates the SB DB.
> > >
> > > The reason for this is
> > >   - lflow_reset_processing() is not called after the reconnection
> > >   - the hmap "installed_flows" is not cleared, because of which
> > >     ofctrl_put skips adding the flows to the switch.
> > >
> > > This patch fixes the issue and also adds a test case to test
> > > this scenario.
> > >
> > > Signed-off-by: Numan Siddique <nusid...@redhat.com>
> > > ---
> >
> > I'm going to pick a nit on this one - is the behavior you are aiming
> > for delete and re-add or just recalculate and leave alone?
>
> >
> > ​In my testing I am seeing that all the OF flows are getting de​
> > leted when I restart ovs-vswitchd.
> > I am testing with the latest master of OVS. I am able to see this on
> > 2 different machines and also in sandbox.
> >
> > I thought that ovn-controller is deleting the flows in the switch
> > when it restarts (https://github.com/openvswitch/ovs/blob/master/
> > ovn/controller/ofctrl.c#L355)
> >
> > Now I tested again and before restarting ovs-vswitchd, I killed ovn-
> > controller. Looks like ovs-vswitchd is clearing the old flows when
> > it restarts. I am not sure if this is the intended behavior. Looks
> > like it is. Please correct me if I am wrong here.
> >
> > ​You can run below commands to reproduce the issue in sandbox​
> >
> > -----------------------------
> >  $make sandbox SANDBOXFLAGS="--ovn"
> >  $ovn/env1/setup.sh
> >  $ovs-ofctl dump-flows br-int
> >  $ovs-appctl -t ovn-controller exit
> >  $ovs-appctl -t ovs-vswitchd exit
> > ​ $ovs-vswitchd --detach --no-chdir --pidfile -vconsole:off --log-
> > file --enable-dummy=override -vvconn -vnetdev_dummy
> >  $ ovs-ofctl dump-flows br-int
> > NXST_FLOW reply (xid=0x4):
> > ------------------------------------
> >
> > You will see that the flows are deleted even if you don't run -
> > "ovs-appctl -t ovn-controller exit".
> >
> > I ask because if it is "delete and re-add" aren't you still disrupting
> > the datapath even if only momentarily?
> >
>
> Ok, so we'll assume that your code is valid for when ovswitchd purges
> the old flows and that's good.
>
> IIRC there is a way to restart ovswitchd via ovs_ctl so that it doesn't
> purge the old flows.  Since I'll argue (as an operator) that is the more
> important case, can you add a unit test for this and verify that your
> patch doesn't leave that path broken?
>
>
Sure. I will do that.

Thanks
Numan
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